Chaco Culture National Historical Park
Encyclopedia
Chaco Culture National Historical Park is a United States National Historical Park
hosting the densest and most exceptional concentration of pueblo
s in the American Southwest
. The park is located in northwestern New Mexico, between Albuquerque
and Farmington
, in a remote canyon cut by the Chaco Wash
. Containing the most sweeping collection of ancient ruins north of Mexico, the park preserves one of the United States' most important pre-Columbian
cultural and historical areas.
Between AD 900 and 1150, Chaco Canyon was a major center of culture for the Ancient Pueblo Peoples
. Chacoans quarried sandstone blocks and hauled timber from great distances, assembling fifteen major complexes which remained the largest buildings in North America until the 19th century. Evidence of archaeoastronomy
at Chaco has been proposed, with the "Sun Dagger" petroglyph at Fajada Butte
a popular example. Many Chacoan buildings may have been aligned to capture the solar and lunar cycles, requiring generations of astronomical observations and centuries of skillfully coordinated construction. Climate change is thought to have led to the emigration of Chacoans and the eventual abandonment of the canyon, beginning with a fifty-year drought commencing in 1130.
Composing a UNESCO
World Heritage Site
located in the arid and sparsely populated Four Corners region, the Chacoan cultural sites are fragile; fears of erosion caused by tourists have led to the closure of Fajada Butte to the public. The sites are considered sacred ancestral homelands by the Hopi
and Pueblo people
, who maintain oral accounts of their historical migration from Chaco and their spiritual relationship to the land. Though park preservation efforts can conflict with native religious beliefs, tribal representatives work closely with the National Park Service to share their knowledge and respect the heritage of the Chacoan culture.
, atop the vast Colorado Plateau
, surrounded by the Chuska Mountains
in the west, the San Juan Mountains
to the north, and the San Pedro Mountains in the east. Ancient Chacoans drew upon dense forests of oak
, piñon
, ponderosa pine
, and juniper
to obtain timber and other resources. The canyon itself, located within lowlands circumscribed by dune fields, ridges, and mountains, is aligned along a roughly northwest-to-southeast axis and is rimmed by flat massifs known as mesa
s. Large gaps between the southwestern cliff faces—side canyons known as rincons—were critical in funneling rain-bearing storms into the canyon and boosting local precipitation levels. The principal Chacoan complexes, such as Pueblo Bonito
, Nuevo Alto
, and Kin Kletso
, have elevations of 6200 foot.
The alluvial
canyon floor slopes downward to the northeast at a gentle grade of 30 feet (9.1 m) per mile (6meters per kilometer); it is bisected by the Chaco Wash
, an arroyo
that rarely bears water. The canyon's main aquifer
s were too deep to be of use to ancient Chacoans: only several smaller and shallower sources supported the small springs that sustained them. Aside from occasional storm runoff coursing through arroyos, substantial surface water—springs, pools, wells—is virtually non-existent.
n supercontinent sundered during the Cretaceous
period, the region became part of a shifting transition zone between a shallow inland sea—the Western Interior Seaway
—and a band of plains and low hills to the west. A sandy and swampy coastline oscillated east and west, alternately submerging and uncovering the area atop the present Colorado Plateau that Chaco Canyon now occupies.
As the Chaco Wash flowed across the upper strata of what is now the 400 feet (121.9 m) Chacra Mesa
, it cut into it, gouging out a broad canyon over the course of millions of years. The mesa comprises sandstone
and shale
formations dating from the Late Cretaceous
, which are of the Mesa Verde formation
. The canyon bottomlands were further eroded, exposing Menefee Shale
bedrock
; this was subsequently buried under roughly 125 feet (38.1 m) of sediment
. The canyon and mesa lie within the "Chaco Core", distinct from the wider Chaco Plateau, the latter a flat region of grassland with infrequent stands of timber. As the Continental Divide
is only 15.5 miles (25 km) east of the canyon, geological characteristics and different patterns of drainage differentiate these two regions both from each other and from the nearby Chaco Slope
, the Gobernador Slope
, and the Chuska Valley
.
and desert steppe, the canyon and wider basin average 8 inches (203.2 mm) of rainfall annually; the park averages 9.1 inches (231.1 mm). Chaco Canyon lies on the leeward side of extensive mountain ranges to the south and west, resulting in a rainshadow effect that fosters the prevailing lack of moisture in the region. The region sees four distinct seasons. Rainfall is most likely between July and September; May and June are the driest months. Orographic precipitation, which results from moisture wrung out of storm systems ascending the mountain ranges around Chaco Canyon, is responsible for most of the summer and winter precipitation; rainfall increases with higher elevation. Occasional aberrant northward excursions of the intertropical convergence zone
may boost precipitation in some years.
Chaco endures remarkable climatic extremes: temperatures range between -38 F, and may swing 60°F (33°C) in one day. The region averages less than 150frost-free days per year, and the local climate swings wildly from years of plentiful rainfall to prolonged drought. The heavy influence of the El Niño-Southern Oscillation
contributes to the canyon's fickle climate.
and several species of cactus
are interspersed with dry scrub forests of piñon
and juniper
, the latter primarily on the mesa tops. The canyon is far drier than other parts of New Mexico located at similar latitudes and elevations, and it lacks the temperate coniferous forests
plentiful to the east. The prevailing sparseness of plants and wildlife was echoed in ancient times, when overpopulation, expanding cultivation, overhunting, habitat destruction, and drought may have led the Chacoans to strip the canyon of wild plants and game. It has been suggested that even during wet periods the canyon was able to sustain only 2,000 people.
Among Chacoan mammals are the plentiful coyote
(Canis latrans); mule deer
, elk
, and pronghorn
also live within the canyon, though they are rarely encountered by visitors. Important smaller carnivores include bobcat
s, badger
s, fox
es, and two species of skunk
. The park hosts abundant populations of rodents, including several prairie dog
towns. Small colonies of bat
s, are present during the summer. The local shortage of water means that relatively few bird species are present; these include roadrunners
, large hawk
s (such as Cooper's hawk
s and American kestrel
s), owl
s, vulture
s, and raven
s, though they are less abundant in the canyon than in the wetter mountain ranges to the east. Sizeable populations of smaller birds, including warblers
, sparrow
s, and house finches
, are also common. Three species of hummingbird
s are present: one is the tiny but highly pugnacious rufous hummingbird
, which compete intensely with the more mild-tempered black-chinned hummingbird
s for breeding habitat in shrubs or trees located near water. Western (prairie) rattlesnakes
are occasionally seen in the backcountry, though various lizards and skink
s are far more abundant.
were hunter-gatherers: the Archaic–Early Basketmaker
people. These small bands descended from nomadic Clovis
big-game hunters who arrived in the Southwest around 10,000 BC. More than 70 campsites from this period, carbon-dated to the period 7000–1500 BC and mostly consisting of stone chips and other leavings, were found in Atlatl Cave and elsewhere within Chaco Canyon, with at least one of the sites located on the canyon floor near an exposed arroyo. The Archaic–Early Basketmaker people were nomadic or semi-nomadic hunter-gatherer
s who over time began making baskets to store gathered plants. By the end of the period, some people cultivated food. Excavation of their campsites and rock shelters has revealed that they made tools, gathered wild plants, and killed and processed game. Slab-lined storage cisterns indicate a change from a wholly nomadic lifestyle.
By 900 BC, Archaic people lived at Atlatl Cave and like sites. They left little evidence of their presence in Chaco Canyon. By AD 490, their descendants, of the Late Basketmaker II Era
, farmed lands around Shabik'eshchee Village and other pit-house
settlements at Chaco.
A small population of Basketmaker
s remained in the Chaco Canyon area. The broad arc of their cultural elaboration culminated around 800, during the Pueblo I Era
, when they were building crescent-shaped stone complexes, each comprising four to five residential suites abutting subterranean kiva
s, large enclosed areas reserved for rites. Such structures characterize the Early Pueblo People
. By 850, the Ancient Pueblo population—the "Anasazi", from a Ute
term adopted by the Navajo
denoting the "ancient ones" or "enemy ancestors"—had rapidly expanded: groups resided in larger, denser pueblos. Strong evidence attests to a canyon-wide turquoise processing and trading industry dating from the 10th century. Around then, the first section of Pueblo Bonito
was built: a curved row of 50 rooms near its present north wall.
The cohesive Chacoan system began unravelling around 1140, perhaps triggered by an extreme fifty-year drought that began in 1130; chronic climatic instability, including a series of severe droughts, again struck the region between 1250 and 1450. Poor water management lead to arroyo cutting; deforestation was extensive and economically devastating: timber for construction had to instead be hauled from outlying mountain ranges such as the Chuska Mountains
, which are over 50 miles (80.5 km) to the west. Outlying communities began to depopulate and, by the end of the century, the buildings in the central canyon had been neatly sealed and abandoned.
Some scholars suggest that violence and warfare, perhaps involving cannibalism, impelled the evacuations. Hints of such include dismembered bodies—dating from Chacoan times—found at two sites within the central canyon. Yet Chacoan complexes showed little evidence of being defended or defensively sited high on cliff faces or atop mesas, and only several minor sites at Chaco evidence the large-scale burning that would suggest enemy raids. Archaeological and cultural evidence leads scientists to believe people from this region migrated south, east, and west into the valleys and drainages of the Little Colorado River
, the Rio Puerco, and the Rio Grande
. Anthropologist Joseph Tainter
deals at length with the structure and decline of Chaco civilization in his 1988 study The Collapse of Complex Societies.
and Shoshone
, were present on the Colorado Plateau beginning in the 12th century. Nomadic Southern Athabaskan speaking peoples, such as the Apache
and Navajo
, succeeded the Pueblo people in this region by the 15th century; in the process, they acquired Chacoan customs and agricultural skills. Ute tribal groups also frequented the region, primarily during hunting and raiding expeditions. The modern Navajo Nation lies west of Chaco Canyon, and many Navajo live in surrounding areas. The arrival of the Spanish in the 17th century inaugurated an era of subjugation and rebellion, with the Chaco Canyon area absorbing Puebloan and Navajo refugees fleeing Spanish rule. In succession, as first Mexico, then the U.S., gained sovereignty over the canyon, military campaigns were launched against the region's remaining inhabitants.
was the first to write about the ruins of Chaco Canyon, referring in 1832 to Pueblo Bonito as "built of fine-grit sandstone". In 1849, a U.S. Army detachment passed through and surveyed the ruins. The canyon was so remote, however, that it was scarcely visited over the next 50 years. After brief reconnaissance work by Smithsonian scholars in the 1870s, formal archaeological work began in 1896 when a party from the American Museum of Natural History
—the "Hyde Exploring Expedition"—began excavating Pueblo Bonito. Spending five summers in the region, they sent over 60,000 artifacts back to New York and operated a series of trading posts.
In 1901 Richard Wetherill
, who had worked for the Hyde expedition, claimed a homestead
of 161 acres (65.2 ha) that included Pueblo Bonito, Pueblo del Arroyo
, and Chetro Ketl
. While investigating Wetherill's land claim, federal land agent Samuel J. Holsinger detailed the physical setting of the canyon and the sites, noted prehistoric road segments and stairways above Chetro Ketl, and documented prehistoric dams and irrigation systems. His report went unpublished and unheeded. It urged the creation of a national park to safeguard Chacoan sites. The next year, Edgar Lee Hewett
, president of New Mexico Normal University (later renamed New Mexico Highlands University
), mapped many Chacoan sites. Hewett and others helped enact the Federal Antiquities Act of 1906
, the first U.S. law to protect relics; it was, in effect, a direct consequence of Wetherill's controversial activities at Chaco. The Act also authorized the President to found national monuments
: on March 11, 1907, Theodore Roosevelt proclaimed Chaco Canyon National Monument. Wetherill relinquished his claims.
In 1920, the National Geographic Society
began an archaeological examination of Chaco Canyon, and appointed Neil Judd
, then 32, to head the project. After a reconnaissance trip that year, Judd proposed to excavate Pueblo Bonito
, the largest ruin at Chaco. Beginning in 1921, Judd spent seven field seasons at Chaco. Living and working conditions were spartan at best. In his memoirs, Judd noted dryly that "Chaco Canyon has its limitations as a summer resort". By 1925, Judd's excavators had removed 100,000 short tons of overburden
, using a team of "35 or more Indians, ten white men, and eight or nine horses". One puzzling discovery was that Judd's team only found 69 hearths in the ruin; winters are cold at Chaco. Judd sent A. E. Douglass
more than 90 specimens for tree-ring dating, then in its infancy. At that time, Douglass had only a "floating" chronology. it was not until 1929 that a Judd-led team found the "missing link". Most of the beams used at Chaco were cut between 1033 and 1092, the height of construction there.
In 1949, the University of New Mexico
deeded over adjoining lands to form an expanded Chaco Canyon National Monument. In return, the university maintained scientific research rights to the area. By 1959, the National Park Service
had constructed a park visitor center, staff housing, and campgrounds. As a historic property of the National Park Service, the National Monument was listed on the National Register of Historic Places
on October 15, 1966. In 1971, researchers Robert Lister and James Judge established the "Chaco Center", a division for cultural research that functioned as a joint project between the University of New Mexico and the National Park Service. A number of multi-disciplinary research projects, archaeological surveys, and limited excavations began during this time. The Chaco Center extensively surveyed the Chacoan roads, well-constructed and heavily built thoroughfares radiating from the central canyon. The results from such research conducted at Pueblo Alto and other sites dramatically altered accepted academic interpretations of both the Chacoan culture and the Four Corners region of the American Southwest.
The richness of the cultural remains at park sites led to the expansion of the small National Monument into the Chaco Culture National Historical Park on December 19, 1980, when an additional 13000 acres (5,260.9 ha) were added to the protected area. In 1987, the park was designated a World Heritage Site
by UNESCO
. To safeguard Chacoan sites on adjacent Bureau of Land Management
and Navajo Nation
lands, the Park Service developed the multi-agency Chaco Culture Archaeological Protection Site program. These initiatives have detailed the presence of more than 2,400 archeological sites within the current park's boundaries; only a small percentage of these have been excavated.
, a federal agency within the Department of the Interior; neighboring federal lands hosting Chacoan roads are controlled by the Bureau of Land Management
. In the 2002–2003 fiscal year, the park's total annual operating budget was 1,434,000. The park has a visitor center, which features the "Chaco Collection Museum", an information desk, a theater, a book store, and a gift shop. Prior to the 1980s, archeological excavations within current park boundaries were intensive: compound walls were dismantled or demolished, and thousands of artifacts were extracted. Starting in 1981, a new approach, informed by traditional Hopi and Pueblo beliefs, stopped such intrusions. Remote sensing
, anthropological study of Indian oral traditions, and dendrochronology—which left Chacoan relics undisturbed—were touted. In this vein, the "Chaco American Indian Consultation Committee" was established in 1991 to give Navajo, Hopi, Pueblo, and other Indian representatives a voice in park oversight.
Current park policy mandates partial restoration of excavated sites. "Backfilling", or re-burying excavated sites with sand, is one such means. Other measures attempt to safeguard the area's ancient ambiance and mystique: the "Chaco Night Sky Program", which seeks to eliminate the impact of light pollution
on the park's acclaimed night skies; under the program, some 14,000 visitors make use of the Chaco Observatory (inaugurated in 1998), park telescopes, and astronomy-related programs. Chacoan relics outside the current park's boundaries have been threatened by development: an example was the proposed competitive leasing of federal lands in the San Juan Basin for surface coal mining beginning in 1983. As ample coal deposits abut the park, this strip mining threatened the web of ancient Chacoan roads. The year-long "Chaco Roads Project" thus documented the roads, which were later protected from mining.
; covering almost 2 acre (0.809372 ha) and comprising at least 650 rooms, it is the largest Great House; in parts of the complex, the structure was four stories high. The builders' use of core-and-veneer architecture and multi-story construction necessitated massive masonry walls up to 3 feet (91.4 cm) thick. Pueblo Bonito is divided into two sections by a wall precisely aligned to run north-south, bisecting the central plaza. A Great Kiva was placed on either side of the wall, creating a symmetrical pattern common to many Chacoan Great Houses. The scale of the complex, upon completion, rivaled that of the Colosseum.
Nearby is Pueblo del Arroyo
. Founded between AD 1050 and 1075, completed in the early 12th century, it sits at a drainage outlet known as South Gap. Casa Rinconada, isolated from the other central sites, sits to the south side of Chaco Wash, adjacent to a Chacoan road leading to a set of steep stairs that reached the top of Chacra Mesa. Its sole kiva stands alone, with no residential or support structures whatever; it did once had a 39 feet (11.9 m) passageway leading from the underground kiva to several above-ground levels. Chetro Ketl
, located near Pueblo Bonito, bears the typical 'D'-shape of many other central complexes, but is slightly smaller. Begun between AD 1020 and 1050, its 450–550 rooms shared one Great Kiva. Experts estimate that it took 29,135man-hours to erect Chetro Ketl alone; Hewett estimated that it took the wood of 5,000 trees and 50 million stone blocks.
Kin Kletso
("Yellow House") was a medium-sized complex located 0.5 miles (804.7 m) west of Pueblo Bonito. It shows strong evidence of construction and occupation by Pueblo peoples from the northern San Juan Basin. Its rectangular shape and design is related to the Pueblo II
cultural group, rather than the Pueblo III style or its Chacoan variant. It contains 55 rooms, four ground-floor kivas, and a two-story cylindrical tower that may have functioned as a kiva or religious center. Evidence of an obsidian
-processing industry was discovered near the village, which was erected between AD 1125 and 1130.
Pueblo Alto
is a Great House of 89 rooms located on a mesa top near the middle of Chaco Canyon, and is 0.6 mile (0.965604 km) from Pueblo Bonito; it was begun between AD 1020 and 1050 during a wider building boom throughout the canyon. Its location made the community visible to most of the inhabitants of the San Juan Basin; indeed, it was only 2.3 miles (3.7 km) north of Tsin Kletsin, on the opposite side of the canyon. The community was the center of a bead- and turquoise
-processing industry that influenced the development of all villages in the canyon; chert
tool production was common. Research at the site conducted by archaeologist Tom Windes suggests only a handful of families, perhaps as few as five to twenty, lived in the complex; this may imply that Pueblo Alto served a primarily non-residential role. Another Great House, Nuevo Alto
, was built on the north mesa near Pueblo Alto; it was founded in the late 12th century, a time when the Chacoan population was declining.
("Small House"), a village built in the AD 1080s, when, in a period of ample rainfall, Chacoan culture was expanding. Its layout featured a smaller, squarer profile; it also lacked the open plazas and separate kivas of its predecessors. Larger, squarer blocks of stone were used in the masonry; kivas were designed in the northern Mesa Verdean tradition. Two miles down the canyon is Peñasco Blanco
("White Bluff"), an arc-shaped compound built atop the canyon's southern rim in five distinct stages between AD 900 and 1125. A cliff painting (the "Supernova Platograph") nearby may record the sighting of the SN 1054
supernova on July 5, 1054.
Hungo Pavi
, located 1 mi (1.6 km) from Una Vida, measured 872 feet (265.8 m) in circumference. Initial probes revealed 72 ground-level rooms, with structures reaching four stories in height; one large circular kiva has been identified. Kin Nahasbas
, built in either the 9th or 10th century, is sited slightly north of Una Vida, positioned at the foot of the north mesa. Limited excavation of it has taken place. Tsin Kletzin
("Charcoal Place"), a compound located on the Chacra Mesa and positioned above Casa Rinconada
, is 2.3 miles (3.7 km) due south of Pueblo Alto, on the opposite side of the canyon. Nearby is Weritos Dam, a massive earthen structure that scientists believe provided Tsin Kletzin with all of its domestic water. The dam worked by retaining stormwater runoff in a reservoir. Massive amounts of silt accumulated during flash floods would have forced the residents to regularly rebuild the dam and dredge the catchment area.
Deeper in the canyon, Una Vida
("One Life") is one of the three oldest Great Houses; construction began around AD 900. Comprising at least two stories and 124 rooms, it shares an arc or "D"-shaped design with its contemporaries, Peñasco Blanco and Pueblo Bonito, but has a unique "dog leg" addition made necessary by topography. It is located in one of the canyon's major side drainages, near Gallo Wash, and was massively expanded after 930. Wijiji
("Greasewood
"), comprising just over one hundred rooms, is the smallest of the Great Houses. Built between AD 1110 and 1115, it was the last Chacoan Great House to be constructed. Somewhat isolated within the narrow wash, it is positioned 1 mi (1.6 km) from neighboring Una Vida. Directly north are communities even more remote: Salmon Ruins
and Aztec Ruins, sited on the San Juan and Animas River
s near Farmington, were built during a thirty-year wet period commencing in AD 1100. Some 60 mi (97 km) directly south of Chaco Canyon, on the Great South Road, lies another cluster of outlying communities. The largest, Kin Nizhoni, stands atop a 7000 feet (2,133.6 m) mesa surrounded by marshy bottomlands.
Ceremonial structures known as kiva
s were built in proportion to the number of rooms in a pueblo. One small kiva was built for roughly every 29 rooms. Nine complexes each hosted an oversized Great Kiva, each up to 63 feet (19.2 m) in diameter. "T"-shaped doorways and stone lintels marked all Chacoan kivas. Though simple and compound walls were often used, Great Houses were primarily constructed of core-and-veneer walls: two parallel load-bearing walls comprising dressed, flat sandstone blocks bound in clay mortar were erected. Gaps between walls were packed with rubble, forming the wall's core. Walls were then covered in a veneer of small sandstone pieces, which were pressed into a layer of binding mud. These surfacing stones were often placed in distinctive patterns. The Chacoan structures altogether required the wood of 200,000 coniferous trees, mostly hauled—on foot—from mountain ranges up to 70 miles (112.7 km) away.
Around this time, the extended Ancestral Puebloan (Anasazi) community experienced a population and construction boom. Throughout the 10th century, Chacoan building techniques spread from the canyon to neighboring regions. By AD 1115 at least 70 outlying pueblos of Chacoan provenance had been built within the 25000 square miles (64,749.7 km²) composing the San Juan Basin. Experts speculate the function of these compounds, some large enough to be considered Great Houses in their own right. Some suggest they may have been more than agricultural communities, perhaps functioning as trading posts or ceremonial sites.
Thirty such outliers spread across 65000 square miles (168,349.2 km²) are connected to the central canyon and to one another by an enigmatic web of six Chacoan road systems. Extending up to 60 miles (96.6 km) in generally straight routes, they appear to have been extensively surveyed and engineered. Their depressed and scraped caliche
beds reach 30 feet (9.1 m) wide; earthen berms or rocks, at times composing low walls, delimit their edges. When necessary, the roads deploy steep stone stairways and rock ramps to surmount cliffs and other obstacles. Though their purpose may never be certain, archaeologist Harold Gladwin
noted that nearby Navajo believe that the Anasazi built the roads to transport timber; archaeologist Neil Judd
offered a similar hypothesis.
and Moon
at visually pivotal times. Chaco's suspected role as a regional center of pilgrimage, where priestly elites staged the ritual smashing of pots—which over time built up at least one hillock composed solely of shards—is thought to underscore this pattern. Two whorl-shaped etchings near the top of Fajada Butte compose the "Sun Dagger" petroglyph, itself tucked behind the eponymous rock panels of the "Three-Slab Site". They are symbolically focal.
It consists of two spirals: one principal and one ancillary. The latter left-hand spiral captured both spring and fall equinoxes; its artifice was revealed by a descending spear of light, itself filtered through the slabs, that shined upon it and split it in two. The former and larger whorl to its right was lit by the titular "sun dagger", which bisected it through another interplay of slab and sun. It struck it, brilliantly, as the summer sun attains its solstice midday peak. The Chacoans were said to be marking, as artist, "Sun Dagger" discoverer, and leading proponent Anna Sofaer puts it, "the middle of time". Each turn of the 9.25-turn large spiral was found to mark one year in the 18.6-year "lunar excursion cycle" of the rising mid-winter full moon. This record is kept by a slab-cast lunar shadow whose edge strikes in succession each ring. As the full "minimum moon" closest to the winter solstice rises, the shadow's edge precisely strikes the center of the larger spiral; it steps outward year by year, ring by ring, until it strikes the outermost edge of it during the full "maximum moon", again in mid-winter.
Fajada Butte bears five other petroglyphs—including a carving of a "rattlesnake", other spirals, and a rectangle—that are conspicuously lit by contrasts between sunbeams and shadows during equinoxes or solstices. Public access to the butte was curtailed when, in 1989, erosion from modern foot traffic was found to be responsible for one of the three screening slabs at the "Sun Dagger" site shifting out of its ancient position; the assemblage of stones has thus lost some of its former spatial and temporal precision as a solar and lunar calendar. In 1990 the screens were stabilized and placed under observation, but the wayward slab was not moved back into its original orientation.
to be sited along a precisely east-west line, an axis that captures the passage of the equinox
sun. The lines perpendicularly bisecting their principal walls are aligned north-south, implying a possible intent to mirror the equinox midday. Pueblo Alto and Tsin Kletsin are also north-south aligned. These two axes form an inverted cross when viewed from above; its northbound reach is extended another 35 mi (56 km) past Pueblo Alto by the ramrod-straight "Great North Road", a pilgrimage route which modern-day Pueblo Indians believe to be an allusion to myths surrounding their arrival from the distant north.
Two shared-latitude but diametrically opposed complexes located some 15 mi (24 km) from the core buildings of the central canyon, Pueblo Pintado and Kin Bineola, each lie on a path from the central canyon that is collinear with the passage and setting of the full mid-winter "minimum moon", which recurs every 18.6 years. Two other complexes less distant from Pueblo Bonito, Una Vida and Peñasco Blanco, share an axis collinear with the passage of the full "maximum moon". The terms "minimum" and "maximum" refer to the azimuthal extreme points in the lunar excursion cycle, or the swings in direction relative to true north that the setting full moon exhibits. It takes roughly 9.25 years for the rising or setting full moon nearest to winter solstice
to proceed from its maximum azimuthal north, or "maximum extremum", to its southernmost azimuth, known as "minimum extremum".
Reasons for the alignments have been offered:
}}
Chaco Culture National Historical Park is a United States National Historical Park
hosting the densest and most exceptional concentration of pueblo
s in the American Southwest
. The park is located in northwestern New Mexico, between Albuquerque
and Farmington
, in a remote canyon cut by the Chaco Wash
. Containing the most sweeping collection of ancient ruins north of Mexico, the park preserves one of the United States' most important pre-Columbian
cultural and historical areas.
Between AD 900 and 1150, Chaco Canyon was a major center of culture for the Ancient Pueblo Peoples
. Chacoans quarried sandstone blocks and hauled timber from great distances, assembling fifteen major complexes which remained the largest buildings in North America until the 19th century. Evidence of archaeoastronomy
at Chaco has been proposed, with the "Sun Dagger" petroglyph at Fajada Butte
a popular example. Many Chacoan buildings may have been aligned to capture the solar and lunar cycles, requiring generations of astronomical observations and centuries of skillfully coordinated construction. Climate change is thought to have led to the emigration of Chacoans and the eventual abandonment of the canyon, beginning with a fifty-year drought commencing in 1130.
Composing a UNESCO
World Heritage Site
located in the arid and sparsely populated Four Corners region, the Chacoan cultural sites are fragile; fears of erosion caused by tourists have led to the closure of Fajada Butte to the public. The sites are considered sacred ancestral homelands by the Hopi
and Pueblo people
, who maintain oral accounts of their historical migration from Chaco and their spiritual relationship to the land. Though park preservation efforts can conflict with native religious beliefs, tribal representatives work closely with the National Park Service to share their knowledge and respect the heritage of the Chacoan culture.
, atop the vast Colorado Plateau
, surrounded by the Chuska Mountains
in the west, the San Juan Mountains
to the north, and the San Pedro Mountains in the east. Ancient Chacoans drew upon dense forests of oak
, piñon
, ponderosa pine
, and juniper
to obtain timber and other resources. The canyon itself, located within lowlands circumscribed by dune fields, ridges, and mountains, is aligned along a roughly northwest-to-southeast axis and is rimmed by flat massifs known as mesa
s. Large gaps between the southwestern cliff faces—side canyons known as rincons—were critical in funneling rain-bearing storms into the canyon and boosting local precipitation levels. The principal Chacoan complexes, such as Pueblo Bonito
, Nuevo Alto
, and Kin Kletso
, have elevations of 6200 foot.
The alluvial
canyon floor slopes downward to the northeast at a gentle grade of 30 feet (9.1 m) per mile (6meters per kilometer); it is bisected by the Chaco Wash
, an arroyo
that rarely bears water. The canyon's main aquifer
s were too deep to be of use to ancient Chacoans: only several smaller and shallower sources supported the small springs that sustained them. Aside from occasional storm runoff coursing through arroyos, substantial surface water—springs, pools, wells—is virtually non-existent.
n supercontinent sundered during the Cretaceous
period, the region became part of a shifting transition zone between a shallow inland sea—the Western Interior Seaway
—and a band of plains and low hills to the west. A sandy and swampy coastline oscillated east and west, alternately submerging and uncovering the area atop the present Colorado Plateau that Chaco Canyon now occupies.
As the Chaco Wash flowed across the upper strata of what is now the 400 feet (121.9 m) Chacra Mesa
, it cut into it, gouging out a broad canyon over the course of millions of years. The mesa comprises sandstone
and shale
formations dating from the Late Cretaceous
, which are of the Mesa Verde formation
. The canyon bottomlands were further eroded, exposing Menefee Shale
bedrock
; this was subsequently buried under roughly 125 feet (38.1 m) of sediment
. The canyon and mesa lie within the "Chaco Core", distinct from the wider Chaco Plateau, the latter a flat region of grassland with infrequent stands of timber. As the Continental Divide
is only 15.5 miles (25 km) east of the canyon, geological characteristics and different patterns of drainage differentiate these two regions both from each other and from the nearby Chaco Slope
, the Gobernador Slope
, and the Chuska Valley
.
and desert steppe, the canyon and wider basin average 8 inches (203.2 mm) of rainfall annually; the park averages 9.1 inches (231.1 mm). Chaco Canyon lies on the leeward side of extensive mountain ranges to the south and west, resulting in a rainshadow effect that fosters the prevailing lack of moisture in the region. The region sees four distinct seasons. Rainfall is most likely between July and September; May and June are the driest months. Orographic precipitation, which results from moisture wrung out of storm systems ascending the mountain ranges around Chaco Canyon, is responsible for most of the summer and winter precipitation; rainfall increases with higher elevation. Occasional aberrant northward excursions of the intertropical convergence zone
may boost precipitation in some years.
Chaco endures remarkable climatic extremes: temperatures range between -38 F, and may swing 60°F (33°C) in one day. The region averages less than 150frost-free days per year, and the local climate swings wildly from years of plentiful rainfall to prolonged drought. The heavy influence of the El Niño-Southern Oscillation
contributes to the canyon's fickle climate.
and several species of cactus
are interspersed with dry scrub forests of piñon
and juniper
, the latter primarily on the mesa tops. The canyon is far drier than other parts of New Mexico located at similar latitudes and elevations, and it lacks the temperate coniferous forests
plentiful to the east. The prevailing sparseness of plants and wildlife was echoed in ancient times, when overpopulation, expanding cultivation, overhunting, habitat destruction, and drought may have led the Chacoans to strip the canyon of wild plants and game. It has been suggested that even during wet periods the canyon was able to sustain only 2,000 people.
Among Chacoan mammals are the plentiful coyote
(Canis latrans); mule deer
, elk
, and pronghorn
also live within the canyon, though they are rarely encountered by visitors. Important smaller carnivores include bobcat
s, badger
s, fox
es, and two species of skunk
. The park hosts abundant populations of rodents, including several prairie dog
towns. Small colonies of bat
s, are present during the summer. The local shortage of water means that relatively few bird species are present; these include roadrunners
, large hawk
s (such as Cooper's hawk
s and American kestrel
s), owl
s, vulture
s, and raven
s, though they are less abundant in the canyon than in the wetter mountain ranges to the east. Sizeable populations of smaller birds, including warblers
, sparrow
s, and house finches
, are also common. Three species of hummingbird
s are present: one is the tiny but highly pugnacious rufous hummingbird
, which compete intensely with the more mild-tempered black-chinned hummingbird
s for breeding habitat in shrubs or trees located near water. Western (prairie) rattlesnakes
are occasionally seen in the backcountry, though various lizards and skink
s are far more abundant.
were hunter-gatherers: the Archaic–Early Basketmaker
people. These small bands descended from nomadic Clovis
big-game hunters who arrived in the Southwest around 10,000 BC. More than 70 campsites from this period, carbon-dated to the period 7000–1500 BC and mostly consisting of stone chips and other leavings, were found in Atlatl Cave and elsewhere within Chaco Canyon, with at least one of the sites located on the canyon floor near an exposed arroyo. The Archaic–Early Basketmaker people were nomadic or semi-nomadic hunter-gatherer
s who over time began making baskets to store gathered plants. By the end of the period, some people cultivated food. Excavation of their campsites and rock shelters has revealed that they made tools, gathered wild plants, and killed and processed game. Slab-lined storage cisterns indicate a change from a wholly nomadic lifestyle.
By 900 BC, Archaic people lived at Atlatl Cave and like sites. They left little evidence of their presence in Chaco Canyon. By AD 490, their descendants, of the Late Basketmaker II Era
, farmed lands around Shabik'eshchee Village and other pit-house
settlements at Chaco.
A small population of Basketmaker
s remained in the Chaco Canyon area. The broad arc of their cultural elaboration culminated around 800, during the Pueblo I Era
, when they were building crescent-shaped stone complexes, each comprising four to five residential suites abutting subterranean kiva
s, large enclosed areas reserved for rites. Such structures characterize the Early Pueblo People
. By 850, the Ancient Pueblo population—the "Anasazi", from a Ute
term adopted by the Navajo
denoting the "ancient ones" or "enemy ancestors"—had rapidly expanded: groups resided in larger, denser pueblos. Strong evidence attests to a canyon-wide turquoise processing and trading industry dating from the 10th century. Around then, the first section of Pueblo Bonito
was built: a curved row of 50 rooms near its present north wall.
The cohesive Chacoan system began unravelling around 1140, perhaps triggered by an extreme fifty-year drought that began in 1130; chronic climatic instability, including a series of severe droughts, again struck the region between 1250 and 1450. Poor water management lead to arroyo cutting; deforestation was extensive and economically devastating: timber for construction had to instead be hauled from outlying mountain ranges such as the Chuska Mountains
, which are over 50 miles (80.5 km) to the west. Outlying communities began to depopulate and, by the end of the century, the buildings in the central canyon had been neatly sealed and abandoned.
Some scholars suggest that violence and warfare, perhaps involving cannibalism, impelled the evacuations. Hints of such include dismembered bodies—dating from Chacoan times—found at two sites within the central canyon. Yet Chacoan complexes showed little evidence of being defended or defensively sited high on cliff faces or atop mesas, and only several minor sites at Chaco evidence the large-scale burning that would suggest enemy raids. Archaeological and cultural evidence leads scientists to believe people from this region migrated south, east, and west into the valleys and drainages of the Little Colorado River
, the Rio Puerco, and the Rio Grande
. Anthropologist Joseph Tainter
deals at length with the structure and decline of Chaco civilization in his 1988 study The Collapse of Complex Societies.
and Shoshone
, were present on the Colorado Plateau beginning in the 12th century. Nomadic Southern Athabaskan speaking peoples, such as the Apache
and Navajo
, succeeded the Pueblo people in this region by the 15th century; in the process, they acquired Chacoan customs and agricultural skills. Ute tribal groups also frequented the region, primarily during hunting and raiding expeditions. The modern Navajo Nation lies west of Chaco Canyon, and many Navajo live in surrounding areas. The arrival of the Spanish in the 17th century inaugurated an era of subjugation and rebellion, with the Chaco Canyon area absorbing Puebloan and Navajo refugees fleeing Spanish rule. In succession, as first Mexico, then the U.S., gained sovereignty over the canyon, military campaigns were launched against the region's remaining inhabitants.
was the first to write about the ruins of Chaco Canyon, referring in 1832 to Pueblo Bonito as "built of fine-grit sandstone". In 1849, a U.S. Army detachment passed through and surveyed the ruins. The canyon was so remote, however, that it was scarcely visited over the next 50 years. After brief reconnaissance work by Smithsonian scholars in the 1870s, formal archaeological work began in 1896 when a party from the American Museum of Natural History
—the "Hyde Exploring Expedition"—began excavating Pueblo Bonito. Spending five summers in the region, they sent over 60,000 artifacts back to New York and operated a series of trading posts.
In 1901 Richard Wetherill
, who had worked for the Hyde expedition, claimed a homestead
of 161 acres (65.2 ha) that included Pueblo Bonito, Pueblo del Arroyo
, and Chetro Ketl
. While investigating Wetherill's land claim, federal land agent Samuel J. Holsinger detailed the physical setting of the canyon and the sites, noted prehistoric road segments and stairways above Chetro Ketl, and documented prehistoric dams and irrigation systems. His report went unpublished and unheeded. It urged the creation of a national park to safeguard Chacoan sites. The next year, Edgar Lee Hewett
, president of New Mexico Normal University (later renamed New Mexico Highlands University
), mapped many Chacoan sites. Hewett and others helped enact the Federal Antiquities Act of 1906
, the first U.S. law to protect relics; it was, in effect, a direct consequence of Wetherill's controversial activities at Chaco. The Act also authorized the President to found national monuments
: on March 11, 1907, Theodore Roosevelt proclaimed Chaco Canyon National Monument. Wetherill relinquished his claims.
In 1920, the National Geographic Society
began an archaeological examination of Chaco Canyon, and appointed Neil Judd
, then 32, to head the project. After a reconnaissance trip that year, Judd proposed to excavate Pueblo Bonito
, the largest ruin at Chaco. Beginning in 1921, Judd spent seven field seasons at Chaco. Living and working conditions were spartan at best. In his memoirs, Judd noted dryly that "Chaco Canyon has its limitations as a summer resort". By 1925, Judd's excavators had removed 100,000 short tons of overburden
, using a team of "35 or more Indians, ten white men, and eight or nine horses". One puzzling discovery was that Judd's team only found 69 hearths in the ruin; winters are cold at Chaco. Judd sent A. E. Douglass
more than 90 specimens for tree-ring dating, then in its infancy. At that time, Douglass had only a "floating" chronology. it was not until 1929 that a Judd-led team found the "missing link". Most of the beams used at Chaco were cut between 1033 and 1092, the height of construction there.
In 1949, the University of New Mexico
deeded over adjoining lands to form an expanded Chaco Canyon National Monument. In return, the university maintained scientific research rights to the area. By 1959, the National Park Service
had constructed a park visitor center, staff housing, and campgrounds. As a historic property of the National Park Service, the National Monument was listed on the National Register of Historic Places
on October 15, 1966. In 1971, researchers Robert Lister and James Judge established the "Chaco Center", a division for cultural research that functioned as a joint project between the University of New Mexico and the National Park Service. A number of multi-disciplinary research projects, archaeological surveys, and limited excavations began during this time. The Chaco Center extensively surveyed the Chacoan roads, well-constructed and heavily built thoroughfares radiating from the central canyon. The results from such research conducted at Pueblo Alto and other sites dramatically altered accepted academic interpretations of both the Chacoan culture and the Four Corners region of the American Southwest.
The richness of the cultural remains at park sites led to the expansion of the small National Monument into the Chaco Culture National Historical Park on December 19, 1980, when an additional 13000 acres (5,260.9 ha) were added to the protected area. In 1987, the park was designated a World Heritage Site
by UNESCO
. To safeguard Chacoan sites on adjacent Bureau of Land Management
and Navajo Nation
lands, the Park Service developed the multi-agency Chaco Culture Archaeological Protection Site program. These initiatives have detailed the presence of more than 2,400 archeological sites within the current park's boundaries; only a small percentage of these have been excavated.
, a federal agency within the Department of the Interior; neighboring federal lands hosting Chacoan roads are controlled by the Bureau of Land Management
. In the 2002–2003 fiscal year, the park's total annual operating budget was 1,434,000. The park has a visitor center, which features the "Chaco Collection Museum", an information desk, a theater, a book store, and a gift shop. Prior to the 1980s, archeological excavations within current park boundaries were intensive: compound walls were dismantled or demolished, and thousands of artifacts were extracted. Starting in 1981, a new approach, informed by traditional Hopi and Pueblo beliefs, stopped such intrusions. Remote sensing
, anthropological study of Indian oral traditions, and dendrochronology—which left Chacoan relics undisturbed—were touted. In this vein, the "Chaco American Indian Consultation Committee" was established in 1991 to give Navajo, Hopi, Pueblo, and other Indian representatives a voice in park oversight.
Current park policy mandates partial restoration of excavated sites. "Backfilling", or re-burying excavated sites with sand, is one such means. Other measures attempt to safeguard the area's ancient ambiance and mystique: the "Chaco Night Sky Program", which seeks to eliminate the impact of light pollution
on the park's acclaimed night skies; under the program, some 14,000 visitors make use of the Chaco Observatory (inaugurated in 1998), park telescopes, and astronomy-related programs. Chacoan relics outside the current park's boundaries have been threatened by development: an example was the proposed competitive leasing of federal lands in the San Juan Basin for surface coal mining beginning in 1983. As ample coal deposits abut the park, this strip mining threatened the web of ancient Chacoan roads. The year-long "Chaco Roads Project" thus documented the roads, which were later protected from mining.
; covering almost 2 acre (0.809372 ha) and comprising at least 650 rooms, it is the largest Great House; in parts of the complex, the structure was four stories high. The builders' use of core-and-veneer architecture and multi-story construction necessitated massive masonry walls up to 3 feet (91.4 cm) thick. Pueblo Bonito is divided into two sections by a wall precisely aligned to run north-south, bisecting the central plaza. A Great Kiva was placed on either side of the wall, creating a symmetrical pattern common to many Chacoan Great Houses. The scale of the complex, upon completion, rivaled that of the Colosseum.
Nearby is Pueblo del Arroyo
. Founded between AD 1050 and 1075, completed in the early 12th century, it sits at a drainage outlet known as South Gap. Casa Rinconada, isolated from the other central sites, sits to the south side of Chaco Wash, adjacent to a Chacoan road leading to a set of steep stairs that reached the top of Chacra Mesa. Its sole kiva stands alone, with no residential or support structures whatever; it did once had a 39 feet (11.9 m) passageway leading from the underground kiva to several above-ground levels. Chetro Ketl
, located near Pueblo Bonito, bears the typical 'D'-shape of many other central complexes, but is slightly smaller. Begun between AD 1020 and 1050, its 450–550 rooms shared one Great Kiva. Experts estimate that it took 29,135man-hours to erect Chetro Ketl alone; Hewett estimated that it took the wood of 5,000 trees and 50 million stone blocks.
Kin Kletso
("Yellow House") was a medium-sized complex located 0.5 miles (804.7 m) west of Pueblo Bonito. It shows strong evidence of construction and occupation by Pueblo peoples from the northern San Juan Basin. Its rectangular shape and design is related to the Pueblo II
cultural group, rather than the Pueblo III style or its Chacoan variant. It contains 55 rooms, four ground-floor kivas, and a two-story cylindrical tower that may have functioned as a kiva or religious center. Evidence of an obsidian
-processing industry was discovered near the village, which was erected between AD 1125 and 1130.
Pueblo Alto
is a Great House of 89 rooms located on a mesa top near the middle of Chaco Canyon, and is 0.6 mile (0.965604 km) from Pueblo Bonito; it was begun between AD 1020 and 1050 during a wider building boom throughout the canyon. Its location made the community visible to most of the inhabitants of the San Juan Basin; indeed, it was only 2.3 miles (3.7 km) north of Tsin Kletsin, on the opposite side of the canyon. The community was the center of a bead- and turquoise
-processing industry that influenced the development of all villages in the canyon; chert
tool production was common. Research at the site conducted by archaeologist Tom Windes suggests only a handful of families, perhaps as few as five to twenty, lived in the complex; this may imply that Pueblo Alto served a primarily non-residential role. Another Great House, Nuevo Alto
, was built on the north mesa near Pueblo Alto; it was founded in the late 12th century, a time when the Chacoan population was declining.
("Small House"), a village built in the AD 1080s, when, in a period of ample rainfall, Chacoan culture was expanding. Its layout featured a smaller, squarer profile; it also lacked the open plazas and separate kivas of its predecessors. Larger, squarer blocks of stone were used in the masonry; kivas were designed in the northern Mesa Verdean tradition. Two miles down the canyon is Peñasco Blanco
("White Bluff"), an arc-shaped compound built atop the canyon's southern rim in five distinct stages between AD 900 and 1125. A cliff painting (the "Supernova Platograph") nearby may record the sighting of the SN 1054
supernova on July 5, 1054.
Hungo Pavi
, located 1 mi (1.6 km) from Una Vida, measured 872 feet (265.8 m) in circumference. Initial probes revealed 72 ground-level rooms, with structures reaching four stories in height; one large circular kiva has been identified. Kin Nahasbas
, built in either the 9th or 10th century, is sited slightly north of Una Vida, positioned at the foot of the north mesa. Limited excavation of it has taken place. Tsin Kletzin
("Charcoal Place"), a compound located on the Chacra Mesa and positioned above Casa Rinconada
, is 2.3 miles (3.7 km) due south of Pueblo Alto, on the opposite side of the canyon. Nearby is Weritos Dam, a massive earthen structure that scientists believe provided Tsin Kletzin with all of its domestic water. The dam worked by retaining stormwater runoff in a reservoir. Massive amounts of silt accumulated during flash floods would have forced the residents to regularly rebuild the dam and dredge the catchment area.
Deeper in the canyon, Una Vida
("One Life") is one of the three oldest Great Houses; construction began around AD 900. Comprising at least two stories and 124 rooms, it shares an arc or "D"-shaped design with its contemporaries, Peñasco Blanco and Pueblo Bonito, but has a unique "dog leg" addition made necessary by topography. It is located in one of the canyon's major side drainages, near Gallo Wash, and was massively expanded after 930. Wijiji
("Greasewood
"), comprising just over one hundred rooms, is the smallest of the Great Houses. Built between AD 1110 and 1115, it was the last Chacoan Great House to be constructed. Somewhat isolated within the narrow wash, it is positioned 1 mi (1.6 km) from neighboring Una Vida. Directly north are communities even more remote: Salmon Ruins
and Aztec Ruins, sited on the San Juan and Animas River
s near Farmington, were built during a thirty-year wet period commencing in AD 1100. Some 60 mi (97 km) directly south of Chaco Canyon, on the Great South Road, lies another cluster of outlying communities. The largest, Kin Nizhoni, stands atop a 7000 feet (2,133.6 m) mesa surrounded by marshy bottomlands.
Ceremonial structures known as kiva
s were built in proportion to the number of rooms in a pueblo. One small kiva was built for roughly every 29 rooms. Nine complexes each hosted an oversized Great Kiva, each up to 63 feet (19.2 m) in diameter. "T"-shaped doorways and stone lintels marked all Chacoan kivas. Though simple and compound walls were often used, Great Houses were primarily constructed of core-and-veneer walls: two parallel load-bearing walls comprising dressed, flat sandstone blocks bound in clay mortar were erected. Gaps between walls were packed with rubble, forming the wall's core. Walls were then covered in a veneer of small sandstone pieces, which were pressed into a layer of binding mud. These surfacing stones were often placed in distinctive patterns. The Chacoan structures altogether required the wood of 200,000 coniferous trees, mostly hauled—on foot—from mountain ranges up to 70 miles (112.7 km) away.
The meticulously designed buildings composing the larger Chacoan complexes did not emerge until around AD 1030. The Chacoans melded pre-planned architectural designs, astronomical alignments, geometry, landscaping, and engineering into ancient urban centers of unique public architecture. Researchers have concluded that the complex may have had a relatively small residential population, with larger groups assembling only temporarily for annual ceremonies. Smaller sites, apparently more residential in character, are scattered near the Great Houses in and around Chaco. The canyon itself runs along one of the lunar alignment lines, suggesting the location was originally chosen for its astronomical significance. If nothing else, this allowed alignment with several other key structures in the canyon.
Around this time, the extended Ancestral Puebloan (Anasazi) community experienced a population and construction boom. Throughout the 10th century, Chacoan building techniques spread from the canyon to neighboring regions. By AD 1115 at least 70 outlying pueblos of Chacoan provenance had been built within the 25000 square miles (64,749.7 km²) composing the San Juan Basin. Experts speculate the function of these compounds, some large enough to be considered Great Houses in their own right. Some suggest they may have been more than agricultural communities, perhaps functioning as trading posts or ceremonial sites.
Thirty such outliers spread across 65000 square miles (168,349.2 km²) are connected to the central canyon and to one another by an enigmatic web of six Chacoan road systems. Extending up to 60 miles (96.6 km) in generally straight routes, they appear to have been extensively surveyed and engineered. Their depressed and scraped caliche
beds reach 30 feet (9.1 m) wide; earthen berms or rocks, at times composing low walls, delimit their edges. When necessary, the roads deploy steep stone stairways and rock ramps to surmount cliffs and other obstacles. Though their purpose may never be certain, archaeologist Harold Gladwin
noted that nearby Navajo believe that the Anasazi built the roads to transport timber; archaeologist Neil Judd
offered a similar hypothesis.
and Moon
at visually pivotal times. Chaco's suspected role as a regional center of pilgrimage, where priestly elites staged the ritual smashing of pots—which over time built up at least one hillock composed solely of shards—is thought to underscore this pattern. Two whorl-shaped etchings near the top of Fajada Butte compose the "Sun Dagger" petroglyph, itself tucked behind the eponymous rock panels of the "Three-Slab Site". They are symbolically focal.
It consists of two spirals: one principal and one ancillary. The latter left-hand spiral captured both spring and fall equinoxes; its artifice was revealed by a descending spear of light, itself filtered through the slabs, that shined upon it and split it in two. The former and larger whorl to its right was lit by the titular "sun dagger", which bisected it through another interplay of slab and sun. It struck it, brilliantly, as the summer sun attains its solstice midday peak. The Chacoans were said to be marking, as artist, "Sun Dagger" discoverer, and leading proponent Anna Sofaer puts it, "the middle of time". Each turn of the 9.25-turn large spiral was found to mark one year in the 18.6-year "lunar excursion cycle" of the rising mid-winter full moon. This record is kept by a slab-cast lunar shadow whose edge strikes in succession each ring. As the full "minimum moon" closest to the winter solstice rises, the shadow's edge precisely strikes the center of the larger spiral; it steps outward year by year, ring by ring, until it strikes the outermost edge of it during the full "maximum moon", again in mid-winter.
Fajada Butte bears five other petroglyphs—including a carving of a "rattlesnake", other spirals, and a rectangle—that are conspicuously lit by contrasts between sunbeams and shadows during equinoxes or solstices. Public access to the butte was curtailed when, in 1989, erosion from modern foot traffic was found to be responsible for one of the three screening slabs at the "Sun Dagger" site shifting out of its ancient position; the assemblage of stones has thus lost some of its former spatial and temporal precision as a solar and lunar calendar. In 1990 the screens were stabilized and placed under observation, but the wayward slab was not moved back into its original orientation.
to be sited along a precisely east-west line, an axis that captures the passage of the equinox
sun. The lines perpendicularly bisecting their principal walls are aligned north-south, implying a possible intent to mirror the equinox midday. Pueblo Alto and Tsin Kletsin are also north-south aligned. These two axes form an inverted cross when viewed from above; its northbound reach is extended another 35 mi (56 km) past Pueblo Alto by the ramrod-straight "Great North Road", a pilgrimage route which modern-day Pueblo Indians believe to be an allusion to myths surrounding their arrival from the distant north.
Two shared-latitude but diametrically opposed complexes located some 15 mi (24 km) from the core buildings of the central canyon, Pueblo Pintado and Kin Bineola, each lie on a path from the central canyon that is collinear with the passage and setting of the full mid-winter "minimum moon", which recurs every 18.6 years. Two other complexes less distant from Pueblo Bonito, Una Vida and Peñasco Blanco, share an axis collinear with the passage of the full "maximum moon". The terms "minimum" and "maximum" refer to the azimuthal extreme points in the lunar excursion cycle, or the swings in direction relative to true north that the setting full moon exhibits. It takes roughly 9.25 years for the rising or setting full moon nearest to winter solstice
to proceed from its maximum azimuthal north, or "maximum extremum", to its southernmost azimuth, known as "minimum extremum".
Reasons for the alignments have been offered:
}}
Chaco Culture National Historical Park is a United States National Historical Park
hosting the densest and most exceptional concentration of pueblo
s in the American Southwest
. The park is located in northwestern New Mexico, between Albuquerque
and Farmington
, in a remote canyon cut by the Chaco Wash
. Containing the most sweeping collection of ancient ruins north of Mexico, the park preserves one of the United States' most important pre-Columbian
cultural and historical areas.
Between AD 900 and 1150, Chaco Canyon was a major center of culture for the Ancient Pueblo Peoples
. Chacoans quarried sandstone blocks and hauled timber from great distances, assembling fifteen major complexes which remained the largest buildings in North America until the 19th century. Evidence of archaeoastronomy
at Chaco has been proposed, with the "Sun Dagger" petroglyph at Fajada Butte
a popular example. Many Chacoan buildings may have been aligned to capture the solar and lunar cycles, requiring generations of astronomical observations and centuries of skillfully coordinated construction. Climate change is thought to have led to the emigration of Chacoans and the eventual abandonment of the canyon, beginning with a fifty-year drought commencing in 1130.
Composing a UNESCO
World Heritage Site
located in the arid and sparsely populated Four Corners region, the Chacoan cultural sites are fragile; fears of erosion caused by tourists have led to the closure of Fajada Butte to the public. The sites are considered sacred ancestral homelands by the Hopi
and Pueblo people
, who maintain oral accounts of their historical migration from Chaco and their spiritual relationship to the land. Though park preservation efforts can conflict with native religious beliefs, tribal representatives work closely with the National Park Service to share their knowledge and respect the heritage of the Chacoan culture.
, atop the vast Colorado Plateau
, surrounded by the Chuska Mountains
in the west, the San Juan Mountains
to the north, and the San Pedro Mountains in the east. Ancient Chacoans drew upon dense forests of oak
, piñon
, ponderosa pine
, and juniper
to obtain timber and other resources. The canyon itself, located within lowlands circumscribed by dune fields, ridges, and mountains, is aligned along a roughly northwest-to-southeast axis and is rimmed by flat massifs known as mesa
s. Large gaps between the southwestern cliff faces—side canyons known as rincons—were critical in funneling rain-bearing storms into the canyon and boosting local precipitation levels. The principal Chacoan complexes, such as Pueblo Bonito
, Nuevo Alto
, and Kin Kletso
, have elevations of 6200 foot.
The alluvial
canyon floor slopes downward to the northeast at a gentle grade of 30 feet (9.1 m) per mile (6meters per kilometer); it is bisected by the Chaco Wash
, an arroyo
that rarely bears water. The canyon's main aquifer
s were too deep to be of use to ancient Chacoans: only several smaller and shallower sources supported the small springs that sustained them. Aside from occasional storm runoff coursing through arroyos, substantial surface water—springs, pools, wells—is virtually non-existent.
n supercontinent sundered during the Cretaceous
period, the region became part of a shifting transition zone between a shallow inland sea—the Western Interior Seaway
—and a band of plains and low hills to the west. A sandy and swampy coastline oscillated east and west, alternately submerging and uncovering the area atop the present Colorado Plateau that Chaco Canyon now occupies.
As the Chaco Wash flowed across the upper strata of what is now the 400 feet (121.9 m) Chacra Mesa
, it cut into it, gouging out a broad canyon over the course of millions of years. The mesa comprises sandstone
and shale
formations dating from the Late Cretaceous
, which are of the Mesa Verde formation
. The canyon bottomlands were further eroded, exposing Menefee Shale
bedrock
; this was subsequently buried under roughly 125 feet (38.1 m) of sediment
. The canyon and mesa lie within the "Chaco Core", distinct from the wider Chaco Plateau, the latter a flat region of grassland with infrequent stands of timber. As the Continental Divide
is only 15.5 miles (25 km) east of the canyon, geological characteristics and different patterns of drainage differentiate these two regions both from each other and from the nearby Chaco Slope
, the Gobernador Slope
, and the Chuska Valley
.
and desert steppe, the canyon and wider basin average 8 inches (203.2 mm) of rainfall annually; the park averages 9.1 inches (231.1 mm). Chaco Canyon lies on the leeward side of extensive mountain ranges to the south and west, resulting in a rainshadow effect that fosters the prevailing lack of moisture in the region. The region sees four distinct seasons. Rainfall is most likely between July and September; May and June are the driest months. Orographic precipitation, which results from moisture wrung out of storm systems ascending the mountain ranges around Chaco Canyon, is responsible for most of the summer and winter precipitation; rainfall increases with higher elevation. Occasional aberrant northward excursions of the intertropical convergence zone
may boost precipitation in some years.
Chaco endures remarkable climatic extremes: temperatures range between -38 F, and may swing 60°F (33°C) in one day. The region averages less than 150frost-free days per year, and the local climate swings wildly from years of plentiful rainfall to prolonged drought. The heavy influence of the El Niño-Southern Oscillation
contributes to the canyon's fickle climate.
and several species of cactus
are interspersed with dry scrub forests of piñon
and juniper
, the latter primarily on the mesa tops. The canyon is far drier than other parts of New Mexico located at similar latitudes and elevations, and it lacks the temperate coniferous forests
plentiful to the east. The prevailing sparseness of plants and wildlife was echoed in ancient times, when overpopulation, expanding cultivation, overhunting, habitat destruction, and drought may have led the Chacoans to strip the canyon of wild plants and game. It has been suggested that even during wet periods the canyon was able to sustain only 2,000 people.
Among Chacoan mammals are the plentiful coyote
(Canis latrans); mule deer
, elk
, and pronghorn
also live within the canyon, though they are rarely encountered by visitors. Important smaller carnivores include bobcat
s, badger
s, fox
es, and two species of skunk
. The park hosts abundant populations of rodents, including several prairie dog
towns. Small colonies of bat
s, are present during the summer. The local shortage of water means that relatively few bird species are present; these include roadrunners
, large hawk
s (such as Cooper's hawk
s and American kestrel
s), owl
s, vulture
s, and raven
s, though they are less abundant in the canyon than in the wetter mountain ranges to the east. Sizeable populations of smaller birds, including warblers
, sparrow
s, and house finches
, are also common. Three species of hummingbird
s are present: one is the tiny but highly pugnacious rufous hummingbird
, which compete intensely with the more mild-tempered black-chinned hummingbird
s for breeding habitat in shrubs or trees located near water. Western (prairie) rattlesnakes
are occasionally seen in the backcountry, though various lizards and skink
s are far more abundant.
were hunter-gatherers: the Archaic–Early Basketmaker
people. These small bands descended from nomadic Clovis
big-game hunters who arrived in the Southwest around 10,000 BC. More than 70 campsites from this period, carbon-dated to the period 7000–1500 BC and mostly consisting of stone chips and other leavings, were found in Atlatl Cave and elsewhere within Chaco Canyon, with at least one of the sites located on the canyon floor near an exposed arroyo. The Archaic–Early Basketmaker people were nomadic or semi-nomadic hunter-gatherer
s who over time began making baskets to store gathered plants. By the end of the period, some people cultivated food. Excavation of their campsites and rock shelters has revealed that they made tools, gathered wild plants, and killed and processed game. Slab-lined storage cisterns indicate a change from a wholly nomadic lifestyle.
By 900 BC, Archaic people lived at Atlatl Cave and like sites. They left little evidence of their presence in Chaco Canyon. By AD 490, their descendants, of the Late Basketmaker II Era
, farmed lands around Shabik'eshchee Village and other pit-house
settlements at Chaco.
A small population of Basketmaker
s remained in the Chaco Canyon area. The broad arc of their cultural elaboration culminated around 800, during the Pueblo I Era
, when they were building crescent-shaped stone complexes, each comprising four to five residential suites abutting subterranean kiva
s, large enclosed areas reserved for rites. Such structures characterize the Early Pueblo People
. By 850, the Ancient Pueblo population—the "Anasazi", from a Ute
term adopted by the Navajo
denoting the "ancient ones" or "enemy ancestors"—had rapidly expanded: groups resided in larger, denser pueblos. Strong evidence attests to a canyon-wide turquoise processing and trading industry dating from the 10th century. Around then, the first section of Pueblo Bonito
was built: a curved row of 50 rooms near its present north wall.
The cohesive Chacoan system began unravelling around 1140, perhaps triggered by an extreme fifty-year drought that began in 1130; chronic climatic instability, including a series of severe droughts, again struck the region between 1250 and 1450. Poor water management lead to arroyo cutting; deforestation was extensive and economically devastating: timber for construction had to instead be hauled from outlying mountain ranges such as the Chuska Mountains
, which are over 50 miles (80.5 km) to the west. Outlying communities began to depopulate and, by the end of the century, the buildings in the central canyon had been neatly sealed and abandoned.
Some scholars suggest that violence and warfare, perhaps involving cannibalism, impelled the evacuations. Hints of such include dismembered bodies—dating from Chacoan times—found at two sites within the central canyon. Yet Chacoan complexes showed little evidence of being defended or defensively sited high on cliff faces or atop mesas, and only several minor sites at Chaco evidence the large-scale burning that would suggest enemy raids. Archaeological and cultural evidence leads scientists to believe people from this region migrated south, east, and west into the valleys and drainages of the Little Colorado River
, the Rio Puerco, and the Rio Grande
. Anthropologist Joseph Tainter
deals at length with the structure and decline of Chaco civilization in his 1988 study The Collapse of Complex Societies.
and Shoshone
, were present on the Colorado Plateau beginning in the 12th century. Nomadic Southern Athabaskan speaking peoples, such as the Apache
and Navajo
, succeeded the Pueblo people in this region by the 15th century; in the process, they acquired Chacoan customs and agricultural skills. Ute tribal groups also frequented the region, primarily during hunting and raiding expeditions. The modern Navajo Nation lies west of Chaco Canyon, and many Navajo live in surrounding areas. The arrival of the Spanish in the 17th century inaugurated an era of subjugation and rebellion, with the Chaco Canyon area absorbing Puebloan and Navajo refugees fleeing Spanish rule. In succession, as first Mexico, then the U.S., gained sovereignty over the canyon, military campaigns were launched against the region's remaining inhabitants.
was the first to write about the ruins of Chaco Canyon, referring in 1832 to Pueblo Bonito as "built of fine-grit sandstone". In 1849, a U.S. Army detachment passed through and surveyed the ruins. The canyon was so remote, however, that it was scarcely visited over the next 50 years. After brief reconnaissance work by Smithsonian scholars in the 1870s, formal archaeological work began in 1896 when a party from the American Museum of Natural History
—the "Hyde Exploring Expedition"—began excavating Pueblo Bonito. Spending five summers in the region, they sent over 60,000 artifacts back to New York and operated a series of trading posts.
In 1901 Richard Wetherill
, who had worked for the Hyde expedition, claimed a homestead
of 161 acres (65.2 ha) that included Pueblo Bonito, Pueblo del Arroyo
, and Chetro Ketl
. While investigating Wetherill's land claim, federal land agent Samuel J. Holsinger detailed the physical setting of the canyon and the sites, noted prehistoric road segments and stairways above Chetro Ketl, and documented prehistoric dams and irrigation systems. His report went unpublished and unheeded. It urged the creation of a national park to safeguard Chacoan sites. The next year, Edgar Lee Hewett
, president of New Mexico Normal University (later renamed New Mexico Highlands University
), mapped many Chacoan sites. Hewett and others helped enact the Federal Antiquities Act of 1906
, the first U.S. law to protect relics; it was, in effect, a direct consequence of Wetherill's controversial activities at Chaco. The Act also authorized the President to found national monuments
: on March 11, 1907, Theodore Roosevelt proclaimed Chaco Canyon National Monument. Wetherill relinquished his claims.
In 1920, the National Geographic Society
began an archaeological examination of Chaco Canyon, and appointed Neil Judd
, then 32, to head the project. After a reconnaissance trip that year, Judd proposed to excavate Pueblo Bonito
, the largest ruin at Chaco. Beginning in 1921, Judd spent seven field seasons at Chaco. Living and working conditions were spartan at best. In his memoirs, Judd noted dryly that "Chaco Canyon has its limitations as a summer resort". By 1925, Judd's excavators had removed 100,000 short tons of overburden
, using a team of "35 or more Indians, ten white men, and eight or nine horses". One puzzling discovery was that Judd's team only found 69 hearths in the ruin; winters are cold at Chaco. Judd sent A. E. Douglass
more than 90 specimens for tree-ring dating, then in its infancy. At that time, Douglass had only a "floating" chronology. it was not until 1929 that a Judd-led team found the "missing link". Most of the beams used at Chaco were cut between 1033 and 1092, the height of construction there.
In 1949, the University of New Mexico
deeded over adjoining lands to form an expanded Chaco Canyon National Monument. In return, the university maintained scientific research rights to the area. By 1959, the National Park Service
had constructed a park visitor center, staff housing, and campgrounds. As a historic property of the National Park Service, the National Monument was listed on the National Register of Historic Places
on October 15, 1966. In 1971, researchers Robert Lister and James Judge established the "Chaco Center", a division for cultural research that functioned as a joint project between the University of New Mexico and the National Park Service. A number of multi-disciplinary research projects, archaeological surveys, and limited excavations began during this time. The Chaco Center extensively surveyed the Chacoan roads, well-constructed and heavily built thoroughfares radiating from the central canyon. The results from such research conducted at Pueblo Alto and other sites dramatically altered accepted academic interpretations of both the Chacoan culture and the Four Corners region of the American Southwest.
The richness of the cultural remains at park sites led to the expansion of the small National Monument into the Chaco Culture National Historical Park on December 19, 1980, when an additional 13000 acres (5,260.9 ha) were added to the protected area. In 1987, the park was designated a World Heritage Site
by UNESCO
. To safeguard Chacoan sites on adjacent Bureau of Land Management
and Navajo Nation
lands, the Park Service developed the multi-agency Chaco Culture Archaeological Protection Site program. These initiatives have detailed the presence of more than 2,400 archeological sites within the current park's boundaries; only a small percentage of these have been excavated.
, a federal agency within the Department of the Interior; neighboring federal lands hosting Chacoan roads are controlled by the Bureau of Land Management
. In the 2002–2003 fiscal year, the park's total annual operating budget was 1,434,000. The park has a visitor center, which features the "Chaco Collection Museum", an information desk, a theater, a book store, and a gift shop. Prior to the 1980s, archeological excavations within current park boundaries were intensive: compound walls were dismantled or demolished, and thousands of artifacts were extracted. Starting in 1981, a new approach, informed by traditional Hopi and Pueblo beliefs, stopped such intrusions. Remote sensing
, anthropological study of Indian oral traditions, and dendrochronology—which left Chacoan relics undisturbed—were touted. In this vein, the "Chaco American Indian Consultation Committee" was established in 1991 to give Navajo, Hopi, Pueblo, and other Indian representatives a voice in park oversight.
Current park policy mandates partial restoration of excavated sites. "Backfilling", or re-burying excavated sites with sand, is one such means. Other measures attempt to safeguard the area's ancient ambiance and mystique: the "Chaco Night Sky Program", which seeks to eliminate the impact of light pollution
on the park's acclaimed night skies; under the program, some 14,000 visitors make use of the Chaco Observatory (inaugurated in 1998), park telescopes, and astronomy-related programs. Chacoan relics outside the current park's boundaries have been threatened by development: an example was the proposed competitive leasing of federal lands in the San Juan Basin for surface coal mining beginning in 1983. As ample coal deposits abut the park, this strip mining threatened the web of ancient Chacoan roads. The year-long "Chaco Roads Project" thus documented the roads, which were later protected from mining.
; covering almost 2 acre (0.809372 ha) and comprising at least 650 rooms, it is the largest Great House; in parts of the complex, the structure was four stories high. The builders' use of core-and-veneer architecture and multi-story construction necessitated massive masonry walls up to 3 feet (91.4 cm) thick. Pueblo Bonito is divided into two sections by a wall precisely aligned to run north-south, bisecting the central plaza. A Great Kiva was placed on either side of the wall, creating a symmetrical pattern common to many Chacoan Great Houses. The scale of the complex, upon completion, rivaled that of the Colosseum.
Nearby is Pueblo del Arroyo
. Founded between AD 1050 and 1075, completed in the early 12th century, it sits at a drainage outlet known as South Gap. Casa Rinconada, isolated from the other central sites, sits to the south side of Chaco Wash, adjacent to a Chacoan road leading to a set of steep stairs that reached the top of Chacra Mesa. Its sole kiva stands alone, with no residential or support structures whatever; it did once had a 39 feet (11.9 m) passageway leading from the underground kiva to several above-ground levels. Chetro Ketl
, located near Pueblo Bonito, bears the typical 'D'-shape of many other central complexes, but is slightly smaller. Begun between AD 1020 and 1050, its 450–550 rooms shared one Great Kiva. Experts estimate that it took 29,135man-hours to erect Chetro Ketl alone; Hewett estimated that it took the wood of 5,000 trees and 50 million stone blocks.
Kin Kletso
("Yellow House") was a medium-sized complex located 0.5 miles (804.7 m) west of Pueblo Bonito. It shows strong evidence of construction and occupation by Pueblo peoples from the northern San Juan Basin. Its rectangular shape and design is related to the Pueblo II
cultural group, rather than the Pueblo III style or its Chacoan variant. It contains 55 rooms, four ground-floor kivas, and a two-story cylindrical tower that may have functioned as a kiva or religious center. Evidence of an obsidian
-processing industry was discovered near the village, which was erected between AD 1125 and 1130.
Pueblo Alto
is a Great House of 89 rooms located on a mesa top near the middle of Chaco Canyon, and is 0.6 mile (0.965604 km) from Pueblo Bonito; it was begun between AD 1020 and 1050 during a wider building boom throughout the canyon. Its location made the community visible to most of the inhabitants of the San Juan Basin; indeed, it was only 2.3 miles (3.7 km) north of Tsin Kletsin, on the opposite side of the canyon. The community was the center of a bead- and turquoise
-processing industry that influenced the development of all villages in the canyon; chert
tool production was common. Research at the site conducted by archaeologist Tom Windes suggests only a handful of families, perhaps as few as five to twenty, lived in the complex; this may imply that Pueblo Alto served a primarily non-residential role. Another Great House, Nuevo Alto
, was built on the north mesa near Pueblo Alto; it was founded in the late 12th century, a time when the Chacoan population was declining.
("Small House"), a village built in the AD 1080s, when, in a period of ample rainfall, Chacoan culture was expanding. Its layout featured a smaller, squarer profile; it also lacked the open plazas and separate kivas of its predecessors. Larger, squarer blocks of stone were used in the masonry; kivas were designed in the northern Mesa Verdean tradition. Two miles down the canyon is Peñasco Blanco
("White Bluff"), an arc-shaped compound built atop the canyon's southern rim in five distinct stages between AD 900 and 1125. A cliff painting (the "Supernova Platograph") nearby may record the sighting of the SN 1054
supernova on July 5, 1054.
Hungo Pavi
, located 1 mi (1.6 km) from Una Vida, measured 872 feet (265.8 m) in circumference. Initial probes revealed 72 ground-level rooms, with structures reaching four stories in height; one large circular kiva has been identified. Kin Nahasbas
, built in either the 9th or 10th century, is sited slightly north of Una Vida, positioned at the foot of the north mesa. Limited excavation of it has taken place. Tsin Kletzin
("Charcoal Place"), a compound located on the Chacra Mesa and positioned above Casa Rinconada
, is 2.3 miles (3.7 km) due south of Pueblo Alto, on the opposite side of the canyon. Nearby is Weritos Dam, a massive earthen structure that scientists believe provided Tsin Kletzin with all of its domestic water. The dam worked by retaining stormwater runoff in a reservoir. Massive amounts of silt accumulated during flash floods would have forced the residents to regularly rebuild the dam and dredge the catchment area.
Deeper in the canyon, Una Vida
("One Life") is one of the three oldest Great Houses; construction began around AD 900. Comprising at least two stories and 124 rooms, it shares an arc or "D"-shaped design with its contemporaries, Peñasco Blanco and Pueblo Bonito, but has a unique "dog leg" addition made necessary by topography. It is located in one of the canyon's major side drainages, near Gallo Wash, and was massively expanded after 930. Wijiji
("Greasewood
"), comprising just over one hundred rooms, is the smallest of the Great Houses. Built between AD 1110 and 1115, it was the last Chacoan Great House to be constructed. Somewhat isolated within the narrow wash, it is positioned 1 mi (1.6 km) from neighboring Una Vida. Directly north are communities even more remote: Salmon Ruins
and Aztec Ruins, sited on the San Juan and Animas River
s near Farmington, were built during a thirty-year wet period commencing in AD 1100. Some 60 mi (97 km) directly south of Chaco Canyon, on the Great South Road, lies another cluster of outlying communities. The largest, Kin Nizhoni, stands atop a 7000 feet (2,133.6 m) mesa surrounded by marshy bottomlands.
Ceremonial structures known as kiva
s were built in proportion to the number of rooms in a pueblo. One small kiva was built for roughly every 29 rooms. Nine complexes each hosted an oversized Great Kiva, each up to 63 feet (19.2 m) in diameter. "T"-shaped doorways and stone lintels marked all Chacoan kivas. Though simple and compound walls were often used, Great Houses were primarily constructed of core-and-veneer walls: two parallel load-bearing walls comprising dressed, flat sandstone blocks bound in clay mortar were erected. Gaps between walls were packed with rubble, forming the wall's core. Walls were then covered in a veneer of small sandstone pieces, which were pressed into a layer of binding mud. These surfacing stones were often placed in distinctive patterns. The Chacoan structures altogether required the wood of 200,000 coniferous trees, mostly hauled—on foot—from mountain ranges up to 70 miles (112.7 km) away.
The meticulously designed buildings composing the larger Chacoan complexes did not emerge until around AD 1030. The Chacoans melded pre-planned architectural designs, astronomical alignments, geometry, landscaping, and engineering into ancient urban centers of unique public architecture. Researchers have concluded that the complex may have had a relatively small residential population, with larger groups assembling only temporarily for annual ceremonies. Smaller sites, apparently more residential in character, are scattered near the Great Houses in and around Chaco. The canyon itself runs along one of the lunar alignment lines, suggesting the location was originally chosen for its astronomical significance. If nothing else, this allowed alignment with several other key structures in the canyon.
Around this time, the extended Ancestral Puebloan (Anasazi) community experienced a population and construction boom. Throughout the 10th century, Chacoan building techniques spread from the canyon to neighboring regions. By AD 1115 at least 70 outlying pueblos of Chacoan provenance had been built within the 25000 square miles (64,749.7 km²) composing the San Juan Basin. Experts speculate the function of these compounds, some large enough to be considered Great Houses in their own right. Some suggest they may have been more than agricultural communities, perhaps functioning as trading posts or ceremonial sites.
Thirty such outliers spread across 65000 square miles (168,349.2 km²) are connected to the central canyon and to one another by an enigmatic web of six Chacoan road systems. Extending up to 60 miles (96.6 km) in generally straight routes, they appear to have been extensively surveyed and engineered. Their depressed and scraped caliche
beds reach 30 feet (9.1 m) wide; earthen berms or rocks, at times composing low walls, delimit their edges. When necessary, the roads deploy steep stone stairways and rock ramps to surmount cliffs and other obstacles. Though their purpose may never be certain, archaeologist Harold Gladwin
noted that nearby Navajo believe that the Anasazi built the roads to transport timber; archaeologist Neil Judd
offered a similar hypothesis.
and Moon
at visually pivotal times. Chaco's suspected role as a regional center of pilgrimage, where priestly elites staged the ritual smashing of pots—which over time built up at least one hillock composed solely of shards—is thought to underscore this pattern. Two whorl-shaped etchings near the top of Fajada Butte compose the "Sun Dagger" petroglyph, itself tucked behind the eponymous rock panels of the "Three-Slab Site". They are symbolically focal.
It consists of two spirals: one principal and one ancillary. The latter left-hand spiral captured both spring and fall equinoxes; its artifice was revealed by a descending spear of light, itself filtered through the slabs, that shined upon it and split it in two. The former and larger whorl to its right was lit by the titular "sun dagger", which bisected it through another interplay of slab and sun. It struck it, brilliantly, as the summer sun attains its solstice midday peak. The Chacoans were said to be marking, as artist, "Sun Dagger" discoverer, and leading proponent Anna Sofaer puts it, "the middle of time". Each turn of the 9.25-turn large spiral was found to mark one year in the 18.6-year "lunar excursion cycle" of the rising mid-winter full moon. This record is kept by a slab-cast lunar shadow whose edge strikes in succession each ring. As the full "minimum moon" closest to the winter solstice rises, the shadow's edge precisely strikes the center of the larger spiral; it steps outward year by year, ring by ring, until it strikes the outermost edge of it during the full "maximum moon", again in mid-winter.
Fajada Butte bears five other petroglyphs—including a carving of a "rattlesnake", other spirals, and a rectangle—that are conspicuously lit by contrasts between sunbeams and shadows during equinoxes or solstices. Public access to the butte was curtailed when, in 1989, erosion from modern foot traffic was found to be responsible for one of the three screening slabs at the "Sun Dagger" site shifting out of its ancient position; the assemblage of stones has thus lost some of its former spatial and temporal precision as a solar and lunar calendar. In 1990 the screens were stabilized and placed under observation, but the wayward slab was not moved back into its original orientation.
to be sited along a precisely east-west line, an axis that captures the passage of the equinox
sun. The lines perpendicularly bisecting their principal walls are aligned north-south, implying a possible intent to mirror the equinox midday. Pueblo Alto and Tsin Kletsin are also north-south aligned. These two axes form an inverted cross when viewed from above; its northbound reach is extended another 35 mi (56 km) past Pueblo Alto by the ramrod-straight "Great North Road", a pilgrimage route which modern-day Pueblo Indians believe to be an allusion to myths surrounding their arrival from the distant north.
Two shared-latitude but diametrically opposed complexes located some 15 mi (24 km) from the core buildings of the central canyon, Pueblo Pintado and Kin Bineola, each lie on a path from the central canyon that is collinear with the passage and setting of the full mid-winter "minimum moon", which recurs every 18.6 years. Two other complexes less distant from Pueblo Bonito, Una Vida and Peñasco Blanco, share an axis collinear with the passage of the full "maximum moon". The terms "minimum" and "maximum" refer to the azimuthal extreme points in the lunar excursion cycle, or the swings in direction relative to true north that the setting full moon exhibits. It takes roughly 9.25 years for the rising or setting full moon nearest to winter solstice
to proceed from its maximum azimuthal north, or "maximum extremum", to its southernmost azimuth, known as "minimum extremum".
Reasons for the alignments have been offered:
Imagery and travel
Other
National Historic Sites (United States)
National Historic Sites are protected areas of national historic significance in the United States. A National Historic Site usually contains a single historical feature directly associated with its subject...
hosting the densest and most exceptional concentration of pueblo
Pueblo
Pueblo is a term used to describe modern communities of Native Americans in the Southwestern United States of America. The first Spanish explorers of the Southwest used this term to describe the communities housed in apartment-like structures built of stone, adobe mud, and other local material...
s in the American Southwest
Southwestern United States
The Southwestern United States is a region defined in different ways by different sources. Broad definitions include nearly a quarter of the United States, including Arizona, California, Colorado, Nevada, New Mexico, Oklahoma, Texas and Utah...
. The park is located in northwestern New Mexico, between Albuquerque
Albuquerque, New Mexico
Albuquerque is the largest city in the state of New Mexico, United States. It is the county seat of Bernalillo County and is situated in the central part of the state, straddling the Rio Grande. The city population was 545,852 as of the 2010 Census and ranks as the 32nd-largest city in the U.S. As...
and Farmington
Farmington, New Mexico
Farmington is a city in San Juan County in the U.S. state of New Mexico. As of the 2010 U.S. Census the city had a total population of 45,877 people. Farmington makes up one of the four Metropolitan Statistical Areas in New Mexico. The U.S...
, in a remote canyon cut by the Chaco Wash
Chaco Wash
The Chaco Wash is an arroyo cutting through Chaco Canyon, which is located in northwestern New Mexico on the Colorado Plateau. Another arroyo known as Escavada Wash is a tributary that feeds in from the northeast, near the western end of Chaco Canyon. Chaco Wash flows northwest to become the...
. Containing the most sweeping collection of ancient ruins north of Mexico, the park preserves one of the United States' most important pre-Columbian
Pre-Columbian
The pre-Columbian era incorporates all period subdivisions in the history and prehistory of the Americas before the appearance of significant European influences on the American continents, spanning the time of the original settlement in the Upper Paleolithic period to European colonization during...
cultural and historical areas.
Between AD 900 and 1150, Chaco Canyon was a major center of culture for the Ancient Pueblo Peoples
Ancient Pueblo Peoples
Ancient Pueblo People or Ancestral Pueblo peoples were an ancient Native American culture centered on the present-day Four Corners area of the United States, comprising southern Utah, northern Arizona, northwest New Mexico, and southern Colorado...
. Chacoans quarried sandstone blocks and hauled timber from great distances, assembling fifteen major complexes which remained the largest buildings in North America until the 19th century. Evidence of archaeoastronomy
Archaeoastronomy
Archaeoastronomy is the study of how people in the past "have understood the phenomena in the sky how they used phenomena in the sky and what role the sky played in their cultures." Clive Ruggles argues it is misleading to consider archaeoastronomy to be the study of ancient astronomy, as modern...
at Chaco has been proposed, with the "Sun Dagger" petroglyph at Fajada Butte
Fajada Butte
Fajada Butte is in Chaco Culture National Historical Park, in northwest New Mexico.Fajada Butte rises 135 meters above the canyon floor. Although there is no water source on the butte, there are ruins of small cliff dwellings in the higher regions of the butte...
a popular example. Many Chacoan buildings may have been aligned to capture the solar and lunar cycles, requiring generations of astronomical observations and centuries of skillfully coordinated construction. Climate change is thought to have led to the emigration of Chacoans and the eventual abandonment of the canyon, beginning with a fifty-year drought commencing in 1130.
Composing a UNESCO
UNESCO
The United Nations Educational, Scientific and Cultural Organization is a specialized agency of the United Nations...
World Heritage Site
World Heritage Site
A UNESCO World Heritage Site is a place that is listed by the UNESCO as of special cultural or physical significance...
located in the arid and sparsely populated Four Corners region, the Chacoan cultural sites are fragile; fears of erosion caused by tourists have led to the closure of Fajada Butte to the public. The sites are considered sacred ancestral homelands by the Hopi
Hopi
The Hopi are a federally recognized tribe of indigenous Native American people, who primarily live on the Hopi Reservation in northeastern Arizona. The Hopi area according to the 2000 census has a population of 6,946 people. Their Hopi language is one of the 30 of the Uto-Aztecan language...
and Pueblo people
Pueblo people
The Pueblo people are a Native American people in the Southwestern United States. Their traditional economy is based on agriculture and trade. When first encountered by the Spanish in the 16th century, they were living in villages that the Spanish called pueblos, meaning "towns". Of the 21...
, who maintain oral accounts of their historical migration from Chaco and their spiritual relationship to the land. Though park preservation efforts can conflict with native religious beliefs, tribal representatives work closely with the National Park Service to share their knowledge and respect the heritage of the Chacoan culture.
Geography
Chaco Canyon lies within the San Juan BasinSan Juan Basin
The San Juan Basin is a geologic structural basin in the Four Corners region of the Southwestern United States; its main portion covers around , encompassing much of northwestern New Mexico, southwest Colorado, and parts of Arizona and Utah....
, atop the vast Colorado Plateau
Colorado Plateau
The Colorado Plateau, also called the Colorado Plateau Province, is a physiographic region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. The province covers an area of 337,000 km2 within western Colorado, northwestern New Mexico,...
, surrounded by the Chuska Mountains
Chuska mountains
The Chuska Mountains are an elongate range on the Colorado Plateau and within the Navajo Nation. The range is about 80 by 15 km , and it trends north-northwest and is crossed by the state line between Arizona and New Mexico. The highlands are a dissected plateau, with an average elevation of...
in the west, the San Juan Mountains
San Juan Mountains
The San Juan Mountains are a high and rugged mountain range in the Rocky Mountains in southwestern Colorado. The area is highly mineralized and figured in the gold and silver mining industry of early Colorado. Major towns, all old mining camps, include Creede, Lake City, Silverton, Ouray, and...
to the north, and the San Pedro Mountains in the east. Ancient Chacoans drew upon dense forests of oak
Oak
An oak is a tree or shrub in the genus Quercus , of which about 600 species exist. "Oak" may also appear in the names of species in related genera, notably Lithocarpus...
, piñon
Pinyon pine
The pinyon pine group grows in the southwestern United States and in Mexico. The trees yield edible pinyon nuts, which were a staple of the Native Americans, and are still widely eaten...
, ponderosa pine
Ponderosa Pine
Pinus ponderosa, commonly known as the Ponderosa Pine, Bull Pine, Blackjack Pine, or Western Yellow Pine, is a widespread and variable pine native to western North America. It was first described by David Douglas in 1826, from eastern Washington near present-day Spokane...
, and juniper
Juniper
Junipers are coniferous plants in the genus Juniperus of the cypress family Cupressaceae. Depending on taxonomic viewpoint, there are between 50-67 species of juniper, widely distributed throughout the northern hemisphere, from the Arctic, south to tropical Africa in the Old World, and to the...
to obtain timber and other resources. The canyon itself, located within lowlands circumscribed by dune fields, ridges, and mountains, is aligned along a roughly northwest-to-southeast axis and is rimmed by flat massifs known as mesa
Mesa
A mesa or table mountain is an elevated area of land with a flat top and sides that are usually steep cliffs. It takes its name from its characteristic table-top shape....
s. Large gaps between the southwestern cliff faces—side canyons known as rincons—were critical in funneling rain-bearing storms into the canyon and boosting local precipitation levels. The principal Chacoan complexes, such as Pueblo Bonito
Pueblo Bonito
Pueblo Bonito, the largest and best known Great House in Chaco Culture National Historical Park, northern New Mexico, was built by ancestral Pueblo people and occupied between AD 828 and 1126....
, Nuevo Alto
Nuevo Alto
Nuevo Alto is a Chacoan Anasazi great house and notable archaeological site located in Chaco Canyon, a canyon in the U.S. state of New Mexico. It was built on the north mesa near Pueblo Alto, and was founded in the late 12th century, a time when the Chacoan population was declining in the canyon;...
, and Kin Kletso
Kin Kletso
Kin Kletso is a Chacoan Anasazi great house and notable archaeological site located in Chaco Culture National Historical Park, located 25 miles southwest of Nageezi, New Mexico, U.S....
, have elevations of 6200 foot.
The alluvial
Alluvium
Alluvium is loose, unconsolidated soil or sediments, eroded, deposited, and reshaped by water in some form in a non-marine setting. Alluvium is typically made up of a variety of materials, including fine particles of silt and clay and larger particles of sand and gravel...
canyon floor slopes downward to the northeast at a gentle grade of 30 feet (9.1 m) per mile (6meters per kilometer); it is bisected by the Chaco Wash
Chaco Wash
The Chaco Wash is an arroyo cutting through Chaco Canyon, which is located in northwestern New Mexico on the Colorado Plateau. Another arroyo known as Escavada Wash is a tributary that feeds in from the northeast, near the western end of Chaco Canyon. Chaco Wash flows northwest to become the...
, an arroyo
Arroyo (creek)
An arroyo , a Spanish word translated as brook, and also called a wash is usually a dry creek or stream bed—gulch that temporarily or seasonally fills and flows after sufficient rain. Wadi is a similar term in Africa. In Spain, a rambla has a similar meaning to arroyo.-Types and processes:Arroyos...
that rarely bears water. The canyon's main aquifer
Aquifer
An aquifer is a wet underground layer of water-bearing permeable rock or unconsolidated materials from which groundwater can be usefully extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology...
s were too deep to be of use to ancient Chacoans: only several smaller and shallower sources supported the small springs that sustained them. Aside from occasional storm runoff coursing through arroyos, substantial surface water—springs, pools, wells—is virtually non-existent.
Geology
After the PangaeaPangaea
Pangaea, Pangæa, or Pangea is hypothesized as a supercontinent that existed during the Paleozoic and Mesozoic eras about 250 million years ago, before the component continents were separated into their current configuration....
n supercontinent sundered during the Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
period, the region became part of a shifting transition zone between a shallow inland sea—the Western Interior Seaway
Western Interior Seaway
The Western Interior Seaway, also called the Cretaceous Seaway, the Niobraran Sea, and the North American Inland Sea, was a huge inland sea that split the continent of North America into two halves, Laramidia and Appalachia, during most of the mid- and late-Cretaceous Period...
—and a band of plains and low hills to the west. A sandy and swampy coastline oscillated east and west, alternately submerging and uncovering the area atop the present Colorado Plateau that Chaco Canyon now occupies.
As the Chaco Wash flowed across the upper strata of what is now the 400 feet (121.9 m) Chacra Mesa
Chacra Mesa
The Chacra Mesa is a high mesa massif composing the southwestern flank of Chaco Canyon, a region that is notable for its rich collection of ancient Chacoan Anasazi archaeological sites....
, it cut into it, gouging out a broad canyon over the course of millions of years. The mesa comprises sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
and shale
Shale
Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...
formations dating from the Late Cretaceous
Late Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
, which are of the Mesa Verde formation
Geologic formation
A formation or geological formation is the fundamental unit of lithostratigraphy. A formation consists of a certain number of rock strata that have a comparable lithology, facies or other similar properties...
. The canyon bottomlands were further eroded, exposing Menefee Shale
Menefee Shale
The Menefee Shale is a geological stratum underlying the Chaco Wash, which is located in the northwestern portion of the U.S. state of New Mexico, in what is now Chaco Culture National Historical Park...
bedrock
Bedrock
In stratigraphy, bedrock is the native consolidated rock underlying the surface of a terrestrial planet, usually the Earth. Above the bedrock is usually an area of broken and weathered unconsolidated rock in the basal subsoil...
; this was subsequently buried under roughly 125 feet (38.1 m) of sediment
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
. The canyon and mesa lie within the "Chaco Core", distinct from the wider Chaco Plateau, the latter a flat region of grassland with infrequent stands of timber. As the Continental Divide
Continental Divide
The Continental Divide of the Americas, or merely the Continental Gulf of Division or Great Divide, is the name given to the principal, and largely mountainous, hydrological divide of the Americas that separates the watersheds that drain into the Pacific Ocean from those river systems that drain...
is only 15.5 miles (25 km) east of the canyon, geological characteristics and different patterns of drainage differentiate these two regions both from each other and from the nearby Chaco Slope
Chaco Slope
The Chaco Slope is a geographical region located in the northwestern portion of the U.S. state of New Mexico. It borders the Chaco Core, which contains both Chacra Mesa and Chaco Canyon. The canyon itself is noted for its Chacoan Anasazi ruins...
, the Gobernador Slope
Gobernador Slope
The Gobernador Slope is a geographical region located in the northwestern portion of the U.S. state of New Mexico. It is near both Chacra Mesa and Chaco Canyon, which are noted for their Chacoan Anasazi ruins. The Chaco Slope is differentiated from the neighboring Chuska Valley, Chaco Core and...
, and the Chuska Valley
Chuska Valley
The Chuska Valley is a geographical region located in the northwestern portion of the U.S. state of New Mexico. Sitting atop the Colorado Plateau in the Four Corners region of the desert Southwest, it is near both Chacra Mesa and Chaco Canyon, which are noted for their Chacoan Anasazi ruins...
.
Climate
An arid region of high xeric scrublandDeserts and xeric shrublands
Deserts and xeric shrublands is a biome characterized by, relating to, or requiring only a small amount of moisture.-Definition and occurrence:...
and desert steppe, the canyon and wider basin average 8 inches (203.2 mm) of rainfall annually; the park averages 9.1 inches (231.1 mm). Chaco Canyon lies on the leeward side of extensive mountain ranges to the south and west, resulting in a rainshadow effect that fosters the prevailing lack of moisture in the region. The region sees four distinct seasons. Rainfall is most likely between July and September; May and June are the driest months. Orographic precipitation, which results from moisture wrung out of storm systems ascending the mountain ranges around Chaco Canyon, is responsible for most of the summer and winter precipitation; rainfall increases with higher elevation. Occasional aberrant northward excursions of the intertropical convergence zone
Intertropical Convergence Zone
The Intertropical Convergence Zone , known by sailors as The Doldrums, is the area encircling the earth near the equator where winds originating in the northern and southern hemispheres come together....
may boost precipitation in some years.
Chaco endures remarkable climatic extremes: temperatures range between -38 F, and may swing 60°F (33°C) in one day. The region averages less than 150frost-free days per year, and the local climate swings wildly from years of plentiful rainfall to prolonged drought. The heavy influence of the El Niño-Southern Oscillation
El Niño-Southern Oscillation
El Niño/La Niña-Southern Oscillation, or ENSO, is a quasiperiodic climate pattern that occurs across the tropical Pacific Ocean roughly every five years...
contributes to the canyon's fickle climate.
Flora and fauna
Chacoan flora typifies that of North American high deserts: sagebrushArtemisia tridentata
Artemisia tridentata is a shrub or small tree from the family Asteraceae. Some botanists treat it in the segregate genus Seriphidium, as S. tridentatum W. A. Weber, but this is not widely followed...
and several species of cactus
Cactus
A cactus is a member of the plant family Cactaceae. Their distinctive appearance is a result of adaptations to conserve water in dry and/or hot environments. In most species, the stem has evolved to become photosynthetic and succulent, while the leaves have evolved into spines...
are interspersed with dry scrub forests of piñon
Pinyon pine
The pinyon pine group grows in the southwestern United States and in Mexico. The trees yield edible pinyon nuts, which were a staple of the Native Americans, and are still widely eaten...
and juniper
Juniper
Junipers are coniferous plants in the genus Juniperus of the cypress family Cupressaceae. Depending on taxonomic viewpoint, there are between 50-67 species of juniper, widely distributed throughout the northern hemisphere, from the Arctic, south to tropical Africa in the Old World, and to the...
, the latter primarily on the mesa tops. The canyon is far drier than other parts of New Mexico located at similar latitudes and elevations, and it lacks the temperate coniferous forests
Temperate coniferous forests
Temperate coniferous forest is a terrestrial biome found in temperate regions of the world with warm summers and cool winters and adequate rainfall to sustain a forest. In most temperate coniferous forests, evergreen conifers predominate, while some are a mix of conifers and broadleaf evergreen...
plentiful to the east. The prevailing sparseness of plants and wildlife was echoed in ancient times, when overpopulation, expanding cultivation, overhunting, habitat destruction, and drought may have led the Chacoans to strip the canyon of wild plants and game. It has been suggested that even during wet periods the canyon was able to sustain only 2,000 people.
Among Chacoan mammals are the plentiful coyote
Coyote
The coyote , also known as the American jackal or the prairie wolf, is a species of canine found throughout North and Central America, ranging from Panama in the south, north through Mexico, the United States and Canada...
(Canis latrans); mule deer
Mule Deer
The mule deer is a deer indigenous to western North America. The Mule Deer gets its name from its large mule-like ears. There are believed to be several subspecies, including the black-tailed deer...
, elk
Elk
The Elk is the large deer, also called Cervus canadensis or wapiti, of North America and eastern Asia.Elk may also refer to:Other antlered mammals:...
, and pronghorn
Pronghorn
The pronghorn is a species of artiodactyl mammal endemic to interior western and central North America. Though not an antelope, it is often known colloquially in North America as the prong buck, pronghorn antelope, or simply antelope, as it closely resembles the true antelopes of the Old World and...
also live within the canyon, though they are rarely encountered by visitors. Important smaller carnivores include bobcat
Bobcat
The bobcat is a North American mammal of the cat family Felidae, appearing during the Irvingtonian stage of around 1.8 million years ago . With twelve recognized subspecies, it ranges from southern Canada to northern Mexico, including most of the continental United States...
s, badger
Badger
Badgers are short-legged omnivores in the weasel family, Mustelidae. There are nine species of badger, in three subfamilies : Melinae , Mellivorinae , and Taxideinae...
s, fox
Fox
Fox is a common name for many species of omnivorous mammals belonging to the Canidae family. Foxes are small to medium-sized canids , characterized by possessing a long narrow snout, and a bushy tail .Members of about 37 species are referred to as foxes, of which only 12 species actually belong to...
es, and two species of skunk
Skunk
Skunks are mammals best known for their ability to secrete a liquid with a strong, foul odor. General appearance varies from species to species, from black-and-white to brown or cream colored. Skunks belong to the family Mephitidae and to the order Carnivora...
. The park hosts abundant populations of rodents, including several prairie dog
Prairie dog
Prairie dogs are burrowing rodents native to the grasslands of North America. There are five different species of prairie dogs: black-tailed, white-tailed, Gunnison's, Utah and Mexican prairie dogs. They are a type of ground squirrel, found in the United States, Canada and Mexico...
towns. Small colonies of bat
Bat
Bats are mammals of the order Chiroptera "hand" and pteron "wing") whose forelimbs form webbed wings, making them the only mammals naturally capable of true and sustained flight. By contrast, other mammals said to fly, such as flying squirrels, gliding possums, and colugos, glide rather than fly,...
s, are present during the summer. The local shortage of water means that relatively few bird species are present; these include roadrunners
Geococcyx
The roadrunners are two species of bird in the genus Geococcyx of the cuckoo family, Cuculidae, native to North and Central America...
, large hawk
Hawk
The term hawk can be used in several ways:* In strict usage in Australia and Africa, to mean any of the species in the subfamily Accipitrinae, which comprises the genera Accipiter, Micronisus, Melierax, Urotriorchis and Megatriorchis. The large and widespread Accipiter genus includes goshawks,...
s (such as Cooper's hawk
Cooper's Hawk
Cooper's Hawk is a medium-sized hawk native to the North American continent and found from Canada to Mexico. As in many birds of prey, the male is smaller than the female...
s and American kestrel
American Kestrel
The American Kestrel , sometimes colloquially known as the Sparrow Hawk, is a small falcon, and the only kestrel found in the Americas. It is the most common falcon in North America, and is found in a wide variety of habitats. At long, it is also the smallest falcon in North America...
s), owl
Owl
Owls are a group of birds that belong to the order Strigiformes, constituting 200 bird of prey species. Most are solitary and nocturnal, with some exceptions . Owls hunt mostly small mammals, insects, and other birds, although a few species specialize in hunting fish...
s, vulture
Vulture
Vulture is the name given to two groups of convergently evolved scavenging birds, the New World Vultures including the well-known Californian and Andean Condors, and the Old World Vultures including the birds which are seen scavenging on carcasses of dead animals on African plains...
s, and raven
Raven
Raven is the common name given to several larger-bodied members of the genus Corvus—but in Europe and North America the Common Raven is normally implied...
s, though they are less abundant in the canyon than in the wetter mountain ranges to the east. Sizeable populations of smaller birds, including warblers
New World warbler
The New World warblers or wood-warblers are a group of small, often colorful, passerine birds restricted to the New World. They are not related to the Old World warblers or the Australian warblers....
, sparrow
Sparrow
The sparrows are a family of small passerine birds, Passeridae. They are also known as true sparrows, or Old World sparrows, names also used for a genus of the family, Passer...
s, and house finches
House Finch
The House Finch is a bird in the finch family Fringillidae, which is found in North America. This species and the other "American rosefinches" are usually placed in the rosefinch genus Carpodacus...
, are also common. Three species of hummingbird
Hummingbird
Hummingbirds are birds that comprise the family Trochilidae. They are among the smallest of birds, most species measuring in the 7.5–13 cm range. Indeed, the smallest extant bird species is a hummingbird, the 5-cm Bee Hummingbird. They can hover in mid-air by rapidly flapping their wings...
s are present: one is the tiny but highly pugnacious rufous hummingbird
Rufous Hummingbird
The Rufous Hummingbird is a small hummingbird, about 8 cm long with a long, straight and very slender bill. The female is slightly larger than the male.-Description:...
, which compete intensely with the more mild-tempered black-chinned hummingbird
Black-chinned Hummingbird
The Black-chinned Hummingbird is a small hummingbird.Adults are metallic green above and white below with green flanks. Their bill is long, straight and very slender. The adult male has a black face and chin, a glossy purple throat band and a dark forked tail...
s for breeding habitat in shrubs or trees located near water. Western (prairie) rattlesnakes
Crotalus oreganus
Crotalus oreganus is a venomous pitviper species found in North America in the western United States, parts of British Columbia and northwestern Mexico. Seven subspecies are currently recognized, including the nominate subspecies described here....
are occasionally seen in the backcountry, though various lizards and skink
Skink
Skinks are lizards belonging to the family Scincidae. Together with several other lizard families, including Lacertidae , they comprise the superfamily or infraorder Scincomorpha...
s are far more abundant.
Archaic–Early Basketmakers
The first people in the San Juan BasinSan Juan Basin
The San Juan Basin is a geologic structural basin in the Four Corners region of the Southwestern United States; its main portion covers around , encompassing much of northwestern New Mexico, southwest Colorado, and parts of Arizona and Utah....
were hunter-gatherers: the Archaic–Early Basketmaker
Archaic–Early Basketmaker Era
The Archaic–Early Basketmaker Era, 7000 - 1500 BC was an Archaic cultural period of ancestors to the Ancient Pueblo People. They were distinguished from other Archaic people of the Southwest by their basketry which was used to gather and store food...
people. These small bands descended from nomadic Clovis
Clovis culture
The Clovis culture is a prehistoric Paleo-Indian culture that first appears 11,500 RCYBP , at the end of the last glacial period, characterized by the manufacture of "Clovis points" and distinctive bone and ivory tools...
big-game hunters who arrived in the Southwest around 10,000 BC. More than 70 campsites from this period, carbon-dated to the period 7000–1500 BC and mostly consisting of stone chips and other leavings, were found in Atlatl Cave and elsewhere within Chaco Canyon, with at least one of the sites located on the canyon floor near an exposed arroyo. The Archaic–Early Basketmaker people were nomadic or semi-nomadic hunter-gatherer
Hunter-gatherer
A hunter-gatherer or forage society is one in which most or all food is obtained from wild plants and animals, in contrast to agricultural societies which rely mainly on domesticated species. Hunting and gathering was the ancestral subsistence mode of Homo, and all modern humans were...
s who over time began making baskets to store gathered plants. By the end of the period, some people cultivated food. Excavation of their campsites and rock shelters has revealed that they made tools, gathered wild plants, and killed and processed game. Slab-lined storage cisterns indicate a change from a wholly nomadic lifestyle.
Ancestral Puebloans
Late Basketmaker II Era
The Late Basketmaker II Era was a cultural period of Ancient Pueblo People when people began living in pit-houses, raised maize and squash, and were proficient basket makers and weavers...
, farmed lands around Shabik'eshchee Village and other pit-house
Pit-house
A pit-house is a dwelling dug into the ground which may also be layered with stone.These structures may be used as places to tell stories, dance, sing, celebrate, and store food. In archaeology, pit-houses are also termed sunken featured buildings and are found in numerous cultures around the world...
settlements at Chaco.
A small population of Basketmaker
Basketmaker (culture)
The Basketmaker culture of the Ancient Pueblo People began about 1500 BC and continued until about AD 500 with the beginning of the Pueblo I Era...
s remained in the Chaco Canyon area. The broad arc of their cultural elaboration culminated around 800, during the Pueblo I Era
Pueblo I Era
The Pueblo I Era, from AD 750 to 900, was the first period in which Ancient Pueblo People began living in pueblo structures and realized an evolution in architecture, artistic expression, and water conservation...
, when they were building crescent-shaped stone complexes, each comprising four to five residential suites abutting subterranean kiva
Kiva
A kiva is a room used by modern Puebloans for religious rituals, many of them associated with the kachina belief system. Among the modern Hopi and most other Pueblo peoples, kivas are square-walled and underground, and are used for spiritual ceremonies....
s, large enclosed areas reserved for rites. Such structures characterize the Early Pueblo People
Pecos Classification
The Pecos Classification is a division of all known Ancient Pueblo Peoples culture into chronological phases, based on changes in architecture, art, pottery, and cultural remains. The original classification dates back to consensus reached at a 1927 archæological conference held in Pecos, New...
. By 850, the Ancient Pueblo population—the "Anasazi", from a Ute
Ute Tribe
The Ute are an American Indian people now living primarily in Utah and Colorado. There are three Ute tribal reservations: Uintah-Ouray in northeastern Utah ; Southern Ute in Colorado ; and Ute Mountain which primarily lies in Colorado, but extends to Utah and New Mexico . The name of the state of...
term adopted by the Navajo
Navajo language
Navajo or Navaho is an Athabaskan language spoken in the southwestern United States. It is geographically and linguistically one of the Southern Athabaskan languages .Navajo has more speakers than any other Native American language north of the...
denoting the "ancient ones" or "enemy ancestors"—had rapidly expanded: groups resided in larger, denser pueblos. Strong evidence attests to a canyon-wide turquoise processing and trading industry dating from the 10th century. Around then, the first section of Pueblo Bonito
Pueblo Bonito
Pueblo Bonito, the largest and best known Great House in Chaco Culture National Historical Park, northern New Mexico, was built by ancestral Pueblo people and occupied between AD 828 and 1126....
was built: a curved row of 50 rooms near its present north wall.
The cohesive Chacoan system began unravelling around 1140, perhaps triggered by an extreme fifty-year drought that began in 1130; chronic climatic instability, including a series of severe droughts, again struck the region between 1250 and 1450. Poor water management lead to arroyo cutting; deforestation was extensive and economically devastating: timber for construction had to instead be hauled from outlying mountain ranges such as the Chuska Mountains
Chuska mountains
The Chuska Mountains are an elongate range on the Colorado Plateau and within the Navajo Nation. The range is about 80 by 15 km , and it trends north-northwest and is crossed by the state line between Arizona and New Mexico. The highlands are a dissected plateau, with an average elevation of...
, which are over 50 miles (80.5 km) to the west. Outlying communities began to depopulate and, by the end of the century, the buildings in the central canyon had been neatly sealed and abandoned.
Some scholars suggest that violence and warfare, perhaps involving cannibalism, impelled the evacuations. Hints of such include dismembered bodies—dating from Chacoan times—found at two sites within the central canyon. Yet Chacoan complexes showed little evidence of being defended or defensively sited high on cliff faces or atop mesas, and only several minor sites at Chaco evidence the large-scale burning that would suggest enemy raids. Archaeological and cultural evidence leads scientists to believe people from this region migrated south, east, and west into the valleys and drainages of the Little Colorado River
Little Colorado River
The Little Colorado River is a river in the U.S. state of Arizona, providing the principal drainage from the Painted Desert region. Together with its major tributary, the Puerco River, it drains an area of about in eastern Arizona and western New Mexico...
, the Rio Puerco, and the Rio Grande
Rio Grande
The Rio Grande is a river that flows from southwestern Colorado in the United States to the Gulf of Mexico. Along the way it forms part of the Mexico – United States border. Its length varies as its course changes...
. Anthropologist Joseph Tainter
Joseph Tainter
Joseph A. Tainter is a U.S. anthropologist and historian.Tainter studied anthropology at the University of California and Northwestern University, where he received his Ph.D. in 1975. He is currently a professor in the Department of Environment and Society at Utah State University...
deals at length with the structure and decline of Chaco civilization in his 1988 study The Collapse of Complex Societies.
Athabaskan succession
Numic-speaking peoples, such as the UteUte Tribe
The Ute are an American Indian people now living primarily in Utah and Colorado. There are three Ute tribal reservations: Uintah-Ouray in northeastern Utah ; Southern Ute in Colorado ; and Ute Mountain which primarily lies in Colorado, but extends to Utah and New Mexico . The name of the state of...
and Shoshone
Shoshone
The Shoshone or Shoshoni are a Native American tribe in the United States with three large divisions: the Northern, the Western and the Eastern....
, were present on the Colorado Plateau beginning in the 12th century. Nomadic Southern Athabaskan speaking peoples, such as the Apache
Apache
Apache is the collective term for several culturally related groups of Native Americans in the United States originally from the Southwest United States. These indigenous peoples of North America speak a Southern Athabaskan language, which is related linguistically to the languages of Athabaskan...
and Navajo
Navajo people
The Navajo of the Southwestern United States are the largest single federally recognized tribe of the United States of America. The Navajo Nation has 300,048 enrolled tribal members. The Navajo Nation constitutes an independent governmental body which manages the Navajo Indian reservation in the...
, succeeded the Pueblo people in this region by the 15th century; in the process, they acquired Chacoan customs and agricultural skills. Ute tribal groups also frequented the region, primarily during hunting and raiding expeditions. The modern Navajo Nation lies west of Chaco Canyon, and many Navajo live in surrounding areas. The arrival of the Spanish in the 17th century inaugurated an era of subjugation and rebellion, with the Chaco Canyon area absorbing Puebloan and Navajo refugees fleeing Spanish rule. In succession, as first Mexico, then the U.S., gained sovereignty over the canyon, military campaigns were launched against the region's remaining inhabitants.
Excavation and protection
The trader Josiah GreggJosiah Gregg
Josiah Gregg was a merchant, explorer, naturalist, and author of the American Southwest and Northern Mexico regions. He is most famous for his book Commerce of the Prairies.-Early years:...
was the first to write about the ruins of Chaco Canyon, referring in 1832 to Pueblo Bonito as "built of fine-grit sandstone". In 1849, a U.S. Army detachment passed through and surveyed the ruins. The canyon was so remote, however, that it was scarcely visited over the next 50 years. After brief reconnaissance work by Smithsonian scholars in the 1870s, formal archaeological work began in 1896 when a party from the American Museum of Natural History
American Museum of Natural History
The American Museum of Natural History , located on the Upper West Side of Manhattan in New York City, United States, is one of the largest and most celebrated museums in the world...
—the "Hyde Exploring Expedition"—began excavating Pueblo Bonito. Spending five summers in the region, they sent over 60,000 artifacts back to New York and operated a series of trading posts.
In 1901 Richard Wetherill
Richard Wetherill
Richard Wetherill , a member of a prominent Colorado ranching family, was an amateur explorer in the discovery, research and excavation of sites associated with the Ancient Pueblo People...
, who had worked for the Hyde expedition, claimed a homestead
Homestead Act
A homestead act is one of three United States federal laws that gave an applicant freehold title to an area called a "homestead" – typically 160 acres of undeveloped federal land west of the Mississippi River....
of 161 acres (65.2 ha) that included Pueblo Bonito, Pueblo del Arroyo
Pueblo del Arroyo
Pueblo del Arroyo is a Chacoan Anasazi great house and notable archaeological site located in Chaco Canyon, a canyon in the U.S. state of New Mexico. Founded between 1050 and 1075 AD and completed in the early 12th century, it is located near Pueblo Bonito at a drainage outlet known as South Gap....
, and Chetro Ketl
Chetro Ketl
Chetro Ketl is a Chacoan Anasazi great house and notable archaeological site located in Chaco Canyon, a canyon in the U.S. state of New Mexico. In the cliffs behind the ruins there are ancient stairways that lead to prehistoric roadways that connect to Pueblo Bonito...
. While investigating Wetherill's land claim, federal land agent Samuel J. Holsinger detailed the physical setting of the canyon and the sites, noted prehistoric road segments and stairways above Chetro Ketl, and documented prehistoric dams and irrigation systems. His report went unpublished and unheeded. It urged the creation of a national park to safeguard Chacoan sites. The next year, Edgar Lee Hewett
Edgar Lee Hewett
Edgar Lee Hewett, D.Sc., was an archaeologist/anthropologist active in work on the Native American communities of New Mexico and the southwestern United States, and most famous for his role in bringing about the Antiquities Act, a pioneering piece of legislation for the conservation movement...
, president of New Mexico Normal University (later renamed New Mexico Highlands University
New Mexico Highlands University
New Mexico Highlands University is a public university located in Las Vegas, New Mexico.-History:The university was first established as New Mexico Normal School in 1893, with the prominent archaeologist Edgar Lee Hewett serving as its first president...
), mapped many Chacoan sites. Hewett and others helped enact the Federal Antiquities Act of 1906
Antiquities Act
The Antiquities Act of 1906, officially An Act for the Preservation of American Antiquities , is an act passed by the United States Congress and signed into law by Theodore Roosevelt on June 8, 1906, giving the President of the United States authority to, by executive order, restrict the use of...
, the first U.S. law to protect relics; it was, in effect, a direct consequence of Wetherill's controversial activities at Chaco. The Act also authorized the President to found national monuments
U.S. National Monument
A National Monument in the United States is a protected area that is similar to a National Park except that the President of the United States can quickly declare an area of the United States to be a National Monument without the approval of Congress. National monuments receive less funding and...
: on March 11, 1907, Theodore Roosevelt proclaimed Chaco Canyon National Monument. Wetherill relinquished his claims.
In 1920, the National Geographic Society
National Geographic Society
The National Geographic Society , headquartered in Washington, D.C. in the United States, is one of the largest non-profit scientific and educational institutions in the world. Its interests include geography, archaeology and natural science, the promotion of environmental and historical...
began an archaeological examination of Chaco Canyon, and appointed Neil Judd
Neil Judd
Neil Merton Judd was an American archaeologist who studied under the pioneering archaeologist of the American Southwest, Edgar Lee Hewett. He was curator of archaeology at the erstwhile United States National Museum, which later became part of the Smithsonian Institution...
, then 32, to head the project. After a reconnaissance trip that year, Judd proposed to excavate Pueblo Bonito
Pueblo Bonito
Pueblo Bonito, the largest and best known Great House in Chaco Culture National Historical Park, northern New Mexico, was built by ancestral Pueblo people and occupied between AD 828 and 1126....
, the largest ruin at Chaco. Beginning in 1921, Judd spent seven field seasons at Chaco. Living and working conditions were spartan at best. In his memoirs, Judd noted dryly that "Chaco Canyon has its limitations as a summer resort". By 1925, Judd's excavators had removed 100,000 short tons of overburden
Overburden
Overburden is the material that lies above an area of economic or scientific interest in mining and archaeology; most commonly the rock, soil, and ecosystem that lies above a coal seam or ore body. It is also known as 'waste' or 'spoil'...
, using a team of "35 or more Indians, ten white men, and eight or nine horses". One puzzling discovery was that Judd's team only found 69 hearths in the ruin; winters are cold at Chaco. Judd sent A. E. Douglass
A. E. Douglass
A. E. Douglass was an American astronomer. He discovered a correlation between tree rings and the sunspot cycle....
more than 90 specimens for tree-ring dating, then in its infancy. At that time, Douglass had only a "floating" chronology. it was not until 1929 that a Judd-led team found the "missing link". Most of the beams used at Chaco were cut between 1033 and 1092, the height of construction there.
In 1949, the University of New Mexico
University of New Mexico
The University of New Mexico at Albuquerque is a public research university located in Albuquerque, New Mexico, in the United States. It is the state's flagship research institution...
deeded over adjoining lands to form an expanded Chaco Canyon National Monument. In return, the university maintained scientific research rights to the area. By 1959, the National Park Service
National Park Service
The National Park Service is the U.S. federal agency that manages all national parks, many national monuments, and other conservation and historical properties with various title designations...
had constructed a park visitor center, staff housing, and campgrounds. As a historic property of the National Park Service, the National Monument was listed on the National Register of Historic Places
National Register of Historic Places
The National Register of Historic Places is the United States government's official list of districts, sites, buildings, structures, and objects deemed worthy of preservation...
on October 15, 1966. In 1971, researchers Robert Lister and James Judge established the "Chaco Center", a division for cultural research that functioned as a joint project between the University of New Mexico and the National Park Service. A number of multi-disciplinary research projects, archaeological surveys, and limited excavations began during this time. The Chaco Center extensively surveyed the Chacoan roads, well-constructed and heavily built thoroughfares radiating from the central canyon. The results from such research conducted at Pueblo Alto and other sites dramatically altered accepted academic interpretations of both the Chacoan culture and the Four Corners region of the American Southwest.
The richness of the cultural remains at park sites led to the expansion of the small National Monument into the Chaco Culture National Historical Park on December 19, 1980, when an additional 13000 acres (5,260.9 ha) were added to the protected area. In 1987, the park was designated a World Heritage Site
World Heritage Site
A UNESCO World Heritage Site is a place that is listed by the UNESCO as of special cultural or physical significance...
by UNESCO
UNESCO
The United Nations Educational, Scientific and Cultural Organization is a specialized agency of the United Nations...
. To safeguard Chacoan sites on adjacent Bureau of Land Management
Bureau of Land Management
The Bureau of Land Management is an agency within the United States Department of the Interior which administers America's public lands, totaling approximately , or one-eighth of the landmass of the country. The BLM also manages of subsurface mineral estate underlying federal, state and private...
and Navajo Nation
Navajo Nation
The Navajo Nation is a semi-autonomous Native American-governed territory covering , occupying all of northeastern Arizona, the southeastern portion of Utah, and northwestern New Mexico...
lands, the Park Service developed the multi-agency Chaco Culture Archaeological Protection Site program. These initiatives have detailed the presence of more than 2,400 archeological sites within the current park's boundaries; only a small percentage of these have been excavated.
Management
Chaco Culture National Historical Park is managed by the National Park ServiceNational Park Service
The National Park Service is the U.S. federal agency that manages all national parks, many national monuments, and other conservation and historical properties with various title designations...
, a federal agency within the Department of the Interior; neighboring federal lands hosting Chacoan roads are controlled by the Bureau of Land Management
Bureau of Land Management
The Bureau of Land Management is an agency within the United States Department of the Interior which administers America's public lands, totaling approximately , or one-eighth of the landmass of the country. The BLM also manages of subsurface mineral estate underlying federal, state and private...
. In the 2002–2003 fiscal year, the park's total annual operating budget was 1,434,000. The park has a visitor center, which features the "Chaco Collection Museum", an information desk, a theater, a book store, and a gift shop. Prior to the 1980s, archeological excavations within current park boundaries were intensive: compound walls were dismantled or demolished, and thousands of artifacts were extracted. Starting in 1981, a new approach, informed by traditional Hopi and Pueblo beliefs, stopped such intrusions. Remote sensing
Remote sensing
Remote sensing is the acquisition of information about an object or phenomenon, without making physical contact with the object. In modern usage, the term generally refers to the use of aerial sensor technologies to detect and classify objects on Earth by means of propagated signals Remote sensing...
, anthropological study of Indian oral traditions, and dendrochronology—which left Chacoan relics undisturbed—were touted. In this vein, the "Chaco American Indian Consultation Committee" was established in 1991 to give Navajo, Hopi, Pueblo, and other Indian representatives a voice in park oversight.
Current park policy mandates partial restoration of excavated sites. "Backfilling", or re-burying excavated sites with sand, is one such means. Other measures attempt to safeguard the area's ancient ambiance and mystique: the "Chaco Night Sky Program", which seeks to eliminate the impact of light pollution
Light pollution
Light pollution, also known as photopollution or luminous pollution, is excessive or obtrusive artificial light.The International Dark-Sky Association defines light pollution as:...
on the park's acclaimed night skies; under the program, some 14,000 visitors make use of the Chaco Observatory (inaugurated in 1998), park telescopes, and astronomy-related programs. Chacoan relics outside the current park's boundaries have been threatened by development: an example was the proposed competitive leasing of federal lands in the San Juan Basin for surface coal mining beginning in 1983. As ample coal deposits abut the park, this strip mining threatened the web of ancient Chacoan roads. The year-long "Chaco Roads Project" thus documented the roads, which were later protected from mining.
Sites
The Chacoans built their complexes along a 9 mi (14 km) stretch of canyon floor, with the walls of some structures aligned cardinally and others aligned with the 18.6-year cycle of minimum and maximum moonrise and moonset. Nine Great Houses are positioned along the north side of Chaco Wash, at the base of massive sandstone mesas. Other Great Houses are found on mesa tops or in nearby washes and drainage areas. There are fourteen recognized Great Houses, which are grouped below according to geographic positioning with respect to the canyon.Central canyon
The central portion of the canyon contains the largest Chacoan complexes. The most studied is Pueblo BonitoPueblo Bonito
Pueblo Bonito, the largest and best known Great House in Chaco Culture National Historical Park, northern New Mexico, was built by ancestral Pueblo people and occupied between AD 828 and 1126....
; covering almost 2 acre (0.809372 ha) and comprising at least 650 rooms, it is the largest Great House; in parts of the complex, the structure was four stories high. The builders' use of core-and-veneer architecture and multi-story construction necessitated massive masonry walls up to 3 feet (91.4 cm) thick. Pueblo Bonito is divided into two sections by a wall precisely aligned to run north-south, bisecting the central plaza. A Great Kiva was placed on either side of the wall, creating a symmetrical pattern common to many Chacoan Great Houses. The scale of the complex, upon completion, rivaled that of the Colosseum.
Nearby is Pueblo del Arroyo
Pueblo del Arroyo
Pueblo del Arroyo is a Chacoan Anasazi great house and notable archaeological site located in Chaco Canyon, a canyon in the U.S. state of New Mexico. Founded between 1050 and 1075 AD and completed in the early 12th century, it is located near Pueblo Bonito at a drainage outlet known as South Gap....
. Founded between AD 1050 and 1075, completed in the early 12th century, it sits at a drainage outlet known as South Gap. Casa Rinconada, isolated from the other central sites, sits to the south side of Chaco Wash, adjacent to a Chacoan road leading to a set of steep stairs that reached the top of Chacra Mesa. Its sole kiva stands alone, with no residential or support structures whatever; it did once had a 39 feet (11.9 m) passageway leading from the underground kiva to several above-ground levels. Chetro Ketl
Chetro Ketl
Chetro Ketl is a Chacoan Anasazi great house and notable archaeological site located in Chaco Canyon, a canyon in the U.S. state of New Mexico. In the cliffs behind the ruins there are ancient stairways that lead to prehistoric roadways that connect to Pueblo Bonito...
, located near Pueblo Bonito, bears the typical 'D'-shape of many other central complexes, but is slightly smaller. Begun between AD 1020 and 1050, its 450–550 rooms shared one Great Kiva. Experts estimate that it took 29,135man-hours to erect Chetro Ketl alone; Hewett estimated that it took the wood of 5,000 trees and 50 million stone blocks.
Kin Kletso
Kin Kletso
Kin Kletso is a Chacoan Anasazi great house and notable archaeological site located in Chaco Culture National Historical Park, located 25 miles southwest of Nageezi, New Mexico, U.S....
("Yellow House") was a medium-sized complex located 0.5 miles (804.7 m) west of Pueblo Bonito. It shows strong evidence of construction and occupation by Pueblo peoples from the northern San Juan Basin. Its rectangular shape and design is related to the Pueblo II
Pueblo II Era
The Pueblo II Era, AD 900 to 1150, was the second pueblo period of the Ancient Pueblo People of the Four Corners region of the American southwest. During this period people lived in dwellings made of stone and mortar, enjoyed communal activities in kivas, built towers and water conversing dams,...
cultural group, rather than the Pueblo III style or its Chacoan variant. It contains 55 rooms, four ground-floor kivas, and a two-story cylindrical tower that may have functioned as a kiva or religious center. Evidence of an obsidian
Obsidian
Obsidian is a naturally occurring volcanic glass formed as an extrusive igneous rock.It is produced when felsic lava extruded from a volcano cools rapidly with minimum crystal growth...
-processing industry was discovered near the village, which was erected between AD 1125 and 1130.
Pueblo Alto
Pueblo Alto is a Chacoan Anasazi great house and archaeological site located in Chaco Canyon, northwestern New Mexico, United States. The complex, comprising 89 rooms in a single-story layout, is located on a mesa top near the middle of Chaco Canyon; 0.6 miles from Pueblo Bonito, it was...
is a Great House of 89 rooms located on a mesa top near the middle of Chaco Canyon, and is 0.6 mile (0.965604 km) from Pueblo Bonito; it was begun between AD 1020 and 1050 during a wider building boom throughout the canyon. Its location made the community visible to most of the inhabitants of the San Juan Basin; indeed, it was only 2.3 miles (3.7 km) north of Tsin Kletsin, on the opposite side of the canyon. The community was the center of a bead- and turquoise
Turquoise
Turquoise is an opaque, blue-to-green mineral that is a hydrous phosphate of copper and aluminium, with the chemical formula CuAl648·4. It is rare and valuable in finer grades and has been prized as a gem and ornamental stone for thousands of years owing to its unique hue...
-processing industry that influenced the development of all villages in the canyon; chert
Chert
Chert is a fine-grained silica-rich microcrystalline, cryptocrystalline or microfibrous sedimentary rock that may contain small fossils. It varies greatly in color , but most often manifests as gray, brown, grayish brown and light green to rusty red; its color is an expression of trace elements...
tool production was common. Research at the site conducted by archaeologist Tom Windes suggests only a handful of families, perhaps as few as five to twenty, lived in the complex; this may imply that Pueblo Alto served a primarily non-residential role. Another Great House, Nuevo Alto
Nuevo Alto
Nuevo Alto is a Chacoan Anasazi great house and notable archaeological site located in Chaco Canyon, a canyon in the U.S. state of New Mexico. It was built on the north mesa near Pueblo Alto, and was founded in the late 12th century, a time when the Chacoan population was declining in the canyon;...
, was built on the north mesa near Pueblo Alto; it was founded in the late 12th century, a time when the Chacoan population was declining.
Outliers
In Chaco's northern reaches lies another cluster of Great Houses; among the largest are Casa ChiquitaCasa Chiquita
Casa Chiquita is a Chacoan Anasazi great house and archaeological site located in Chaco Canyon, northwestern New Mexico, United States. Located near the old north entrance to the Canyon, its layout features a smaller profile with a square block of rooms surrounding a central elevated round room....
("Small House"), a village built in the AD 1080s, when, in a period of ample rainfall, Chacoan culture was expanding. Its layout featured a smaller, squarer profile; it also lacked the open plazas and separate kivas of its predecessors. Larger, squarer blocks of stone were used in the masonry; kivas were designed in the northern Mesa Verdean tradition. Two miles down the canyon is Peñasco Blanco
Peñasco Blanco
Peñasco Blanco is a Chacoan Anasazi great house and notable archaeological site located in Chaco Canyon, a canyon in San Juan County, New Mexico, United States.. It is an arc-shaped compound built atop the canyon's southern rim; it was constructed in five distinct stages between 900 AD and 1125 AD...
("White Bluff"), an arc-shaped compound built atop the canyon's southern rim in five distinct stages between AD 900 and 1125. A cliff painting (the "Supernova Platograph") nearby may record the sighting of the SN 1054
SN 1054
SN 1054 is a supernova that was first observed as a new "star" in the sky on July 4, 1054 AD, hence its name, and that lasted for a period of around two years. The event was recorded in multiple Chinese and Japanese documents and in one document from the Arab world...
supernova on July 5, 1054.
Hungo Pavi
Hungo Pavi
Hungo Pavi is a Chacoan Anasazi great house and archaeological site located in Chaco Canyon, northwestern New Mexico, United States. A set of ruins located just 1 mile from the ruins of Una Vida, Hungo Pavi measured 872 feet in circumference. Initial explorations revealed 72...
, located 1 mi (1.6 km) from Una Vida, measured 872 feet (265.8 m) in circumference. Initial probes revealed 72 ground-level rooms, with structures reaching four stories in height; one large circular kiva has been identified. Kin Nahasbas
Kin Nahasbas
Kin Nahasbas is a Chacoan Anasazi great house and archaeological site located in Chaco Canyon, 25 miles southwest of Nageezi, New Mexico, United States. Built in either the 9th or 10th centuries, it was major pueblo located slightly north of the Una Vida complex, which is positioned at the foot of...
, built in either the 9th or 10th century, is sited slightly north of Una Vida, positioned at the foot of the north mesa. Limited excavation of it has taken place. Tsin Kletzin
Tsin Kletzin
Tsin Kletzin or Tsin Kletsin is a Chacoan Anasazi archaeological site located on top of South Mesa in Chaco Culture National Historical Park, northwestern New Mexico, United States. It is located 3.2 kilometers south of Pueblo Bonito. Tree-ring dating placed the construction around 1110-1115 A.D...
("Charcoal Place"), a compound located on the Chacra Mesa and positioned above Casa Rinconada
Casa Rinconada
Casa Rinconada is a Chacoan Anasazi archaeological site located atop a ridge adjacent to a small rincon across from Pueblo Bonito in Chaco Culture National Historical Park, northwestern New Mexico, United States....
, is 2.3 miles (3.7 km) due south of Pueblo Alto, on the opposite side of the canyon. Nearby is Weritos Dam, a massive earthen structure that scientists believe provided Tsin Kletzin with all of its domestic water. The dam worked by retaining stormwater runoff in a reservoir. Massive amounts of silt accumulated during flash floods would have forced the residents to regularly rebuild the dam and dredge the catchment area.
Deeper in the canyon, Una Vida
Una Vida
Una Vida is an archaeological site located in Chaco Canyon, San Juan County, New Mexico, United States. Its construction began around 900 AD and it is one of the three earliest Chacoan Anasazi great houses; it...
("One Life") is one of the three oldest Great Houses; construction began around AD 900. Comprising at least two stories and 124 rooms, it shares an arc or "D"-shaped design with its contemporaries, Peñasco Blanco and Pueblo Bonito, but has a unique "dog leg" addition made necessary by topography. It is located in one of the canyon's major side drainages, near Gallo Wash, and was massively expanded after 930. Wijiji
Wijiji
Wijiji is a Chacoan Anasazi great house and notable archaeological site located in Chaco Canyon, a canyon in the U.S. state of New Mexico. Comprising just over 100 rooms, it is the smallest of the Chacoan great houses. Built between 1110 AD and 1115 AD, it was the last Chacoan great house to be...
("Greasewood
Greasewood
Greasewood, Sarcobatus, is a genus of one or two species of flowering plants. Traditionally it has been treated in the family Chenopodiaceae, but the APG II system, of 2003, places it in the family Sarcobataceae....
"), comprising just over one hundred rooms, is the smallest of the Great Houses. Built between AD 1110 and 1115, it was the last Chacoan Great House to be constructed. Somewhat isolated within the narrow wash, it is positioned 1 mi (1.6 km) from neighboring Una Vida. Directly north are communities even more remote: Salmon Ruins
Salmon Ruins
Salmon Ruins is a site in the far northwest of the American state of New Mexico hosting a Chacoan Anasazi great house built between approximately 1088 CE and 1100 CE. The complex contained around 150 ground-level rooms arranged into a D-shaped profile; up to 100 second-floor rooms are estimated to...
and Aztec Ruins, sited on the San Juan and Animas River
Animas River
Animas River is a river in the western United States, a tributary of the San Juan River, part of the Colorado River System. The Spanish named the river "Rio de las Animas Perdidas", "River of the Lost Souls". It is also the last free-flowing river in Colorado. The river's free-flowing status...
s near Farmington, were built during a thirty-year wet period commencing in AD 1100. Some 60 mi (97 km) directly south of Chaco Canyon, on the Great South Road, lies another cluster of outlying communities. The largest, Kin Nizhoni, stands atop a 7000 feet (2,133.6 m) mesa surrounded by marshy bottomlands.
"Great Houses"
Immense complexes known as "Great Houses" embodied worship at Chaco. The Chacoans used masonry techniques unique for their time, and their building constructions lasted decades and even centuries. As architectural forms evolved and centuries passed, the houses kept several core traits. Most apparent is their sheer bulk; complexes averaged more than 200 rooms each, and some enclosed up to 700 rooms. Individual rooms were substantial in size, with higher ceilings than Anasazi works of preceding periods. They were well-planned: vast sections or wings erected were finished in a single stage, rather than in increments. Houses generally faced the south, and plaza areas were almost always girt with edifices of sealed-off rooms or high walls. Houses often stood four or five stories tall, with single-story rooms facing the plaza; room blocks were terraced to allow the tallest sections to compose the pueblo's rear edifice. Rooms were often organized into suites, with front rooms larger than rear, interior, and storage rooms or areas.Ceremonial structures known as kiva
Kiva
A kiva is a room used by modern Puebloans for religious rituals, many of them associated with the kachina belief system. Among the modern Hopi and most other Pueblo peoples, kivas are square-walled and underground, and are used for spiritual ceremonies....
s were built in proportion to the number of rooms in a pueblo. One small kiva was built for roughly every 29 rooms. Nine complexes each hosted an oversized Great Kiva, each up to 63 feet (19.2 m) in diameter. "T"-shaped doorways and stone lintels marked all Chacoan kivas. Though simple and compound walls were often used, Great Houses were primarily constructed of core-and-veneer walls: two parallel load-bearing walls comprising dressed, flat sandstone blocks bound in clay mortar were erected. Gaps between walls were packed with rubble, forming the wall's core. Walls were then covered in a veneer of small sandstone pieces, which were pressed into a layer of binding mud. These surfacing stones were often placed in distinctive patterns. The Chacoan structures altogether required the wood of 200,000 coniferous trees, mostly hauled—on foot—from mountain ranges up to 70 miles (112.7 km) away.
Uses
The meticulously designed buildings composing the larger Chacoan complexes did not emerge until around AD 1030. The Chacoans melded pre-planned architectural designs, astronomical alignments, geometry, landscaping, and engineering into ancient urban centers of unique public architecture. Researchers have concluded that the complex may have had a relatively small residential population, with larger groups assembling only temporarily for annual ceremonies. Smaller sites, apparently more residential in character, are scattered near the Great Houses in and around Chaco. The canyon itself runs along one of the lunar alignment lines, suggesting the location was originally chosen for its astronomical significance. If nothing else, this allowed alignment with several other key structures in the canyon.Around this time, the extended Ancestral Puebloan (Anasazi) community experienced a population and construction boom. Throughout the 10th century, Chacoan building techniques spread from the canyon to neighboring regions. By AD 1115 at least 70 outlying pueblos of Chacoan provenance had been built within the 25000 square miles (64,749.7 km²) composing the San Juan Basin. Experts speculate the function of these compounds, some large enough to be considered Great Houses in their own right. Some suggest they may have been more than agricultural communities, perhaps functioning as trading posts or ceremonial sites.
Thirty such outliers spread across 65000 square miles (168,349.2 km²) are connected to the central canyon and to one another by an enigmatic web of six Chacoan road systems. Extending up to 60 miles (96.6 km) in generally straight routes, they appear to have been extensively surveyed and engineered. Their depressed and scraped caliche
Caliche (Mineral)
Caliche is a sedimentary rock, a hardened deposit of calcium carbonate. This calcium carbonate cements together other materials, including gravel, sand, clay, and silt. It is found in aridisol and mollisol soil orders...
beds reach 30 feet (9.1 m) wide; earthen berms or rocks, at times composing low walls, delimit their edges. When necessary, the roads deploy steep stone stairways and rock ramps to surmount cliffs and other obstacles. Though their purpose may never be certain, archaeologist Harold Gladwin
Harold S. Gladwin
Harold Sterling Gladwin was an American archaeologist, anthropologist and stockbroker born in New York City.-Introduction:Harold Sterling Gladwin was an early twentieth century archaeologist that specialized in...
noted that nearby Navajo believe that the Anasazi built the roads to transport timber; archaeologist Neil Judd
Neil Judd
Neil Merton Judd was an American archaeologist who studied under the pioneering archaeologist of the American Southwest, Edgar Lee Hewett. He was curator of archaeology at the erstwhile United States National Museum, which later became part of the Smithsonian Institution...
offered a similar hypothesis.
"Sun Dagger"
Several parties have advanced the following contested theory: that at least twelve of the fourteen principal Chacoan complexes were sited and aligned in coordination, and that each was oriented along axes that mirrored the passing of the SunSun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
and Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
at visually pivotal times. Chaco's suspected role as a regional center of pilgrimage, where priestly elites staged the ritual smashing of pots—which over time built up at least one hillock composed solely of shards—is thought to underscore this pattern. Two whorl-shaped etchings near the top of Fajada Butte compose the "Sun Dagger" petroglyph, itself tucked behind the eponymous rock panels of the "Three-Slab Site". They are symbolically focal.
It consists of two spirals: one principal and one ancillary. The latter left-hand spiral captured both spring and fall equinoxes; its artifice was revealed by a descending spear of light, itself filtered through the slabs, that shined upon it and split it in two. The former and larger whorl to its right was lit by the titular "sun dagger", which bisected it through another interplay of slab and sun. It struck it, brilliantly, as the summer sun attains its solstice midday peak. The Chacoans were said to be marking, as artist, "Sun Dagger" discoverer, and leading proponent Anna Sofaer puts it, "the middle of time". Each turn of the 9.25-turn large spiral was found to mark one year in the 18.6-year "lunar excursion cycle" of the rising mid-winter full moon. This record is kept by a slab-cast lunar shadow whose edge strikes in succession each ring. As the full "minimum moon" closest to the winter solstice rises, the shadow's edge precisely strikes the center of the larger spiral; it steps outward year by year, ring by ring, until it strikes the outermost edge of it during the full "maximum moon", again in mid-winter.
Fajada Butte bears five other petroglyphs—including a carving of a "rattlesnake", other spirals, and a rectangle—that are conspicuously lit by contrasts between sunbeams and shadows during equinoxes or solstices. Public access to the butte was curtailed when, in 1989, erosion from modern foot traffic was found to be responsible for one of the three screening slabs at the "Sun Dagger" site shifting out of its ancient position; the assemblage of stones has thus lost some of its former spatial and temporal precision as a solar and lunar calendar. In 1990 the screens were stabilized and placed under observation, but the wayward slab was not moved back into its original orientation.
Alignments
The first Great House known to evince fastidious proportioning and alignment was Casa Rinconada: the twinned "T"-shaped portals of its 10 m (33 ft)-radius great kiva were north-south collinear, and axes joining opposing windows passed within 10 cm (4 in) of its center. The Great Houses of Pueblo Bonito and Chetro Ketl were found by the "Solstice Project" and the U.S. National Geodetic SurveyU.S. National Geodetic Survey
National Geodetic Survey, formerly called the U.S. Coast and Geodetic Survey , is a United States federal agency that defines and manages a national coordinate system, providing the foundation for transportation and communication; mapping and charting; and a large number of applications of science...
to be sited along a precisely east-west line, an axis that captures the passage of the equinox
Equinox
An equinox occurs twice a year, when the tilt of the Earth's axis is inclined neither away from nor towards the Sun, the center of the Sun being in the same plane as the Earth's equator...
sun. The lines perpendicularly bisecting their principal walls are aligned north-south, implying a possible intent to mirror the equinox midday. Pueblo Alto and Tsin Kletsin are also north-south aligned. These two axes form an inverted cross when viewed from above; its northbound reach is extended another 35 mi (56 km) past Pueblo Alto by the ramrod-straight "Great North Road", a pilgrimage route which modern-day Pueblo Indians believe to be an allusion to myths surrounding their arrival from the distant north.
Two shared-latitude but diametrically opposed complexes located some 15 mi (24 km) from the core buildings of the central canyon, Pueblo Pintado and Kin Bineola, each lie on a path from the central canyon that is collinear with the passage and setting of the full mid-winter "minimum moon", which recurs every 18.6 years. Two other complexes less distant from Pueblo Bonito, Una Vida and Peñasco Blanco, share an axis collinear with the passage of the full "maximum moon". The terms "minimum" and "maximum" refer to the azimuthal extreme points in the lunar excursion cycle, or the swings in direction relative to true north that the setting full moon exhibits. It takes roughly 9.25 years for the rising or setting full moon nearest to winter solstice
Solstice
A solstice is an astronomical event that happens twice each year when the Sun's apparent position in the sky, as viewed from Earth, reaches its northernmost or southernmost extremes...
to proceed from its maximum azimuthal north, or "maximum extremum", to its southernmost azimuth, known as "minimum extremum".
Reasons for the alignments have been offered:
See also
- Ah-Shi-Sle-Pah Wilderness Study AreaAh-Shi-Sle-Pah Wilderness Study AreaAh-Shi-Sle-Pah Wilderness Study Area is located in San Juan County, New Mexico between Chaco Canyon and the De-Na-Zin Wilderness. The Wilderness Study Area has multicolored badlands, sandstone hoodoos, petrified wood and dinosaur bones, similar to those found in the nearby Bisti Badlands and...
- List of archaeoastronomical sites by country
- List of dwellings of Pueblo peoples
Sources
}}}}
Chaco Culture National Historical Park is a United States National Historical Park
National Historic Sites (United States)
National Historic Sites are protected areas of national historic significance in the United States. A National Historic Site usually contains a single historical feature directly associated with its subject...
hosting the densest and most exceptional concentration of pueblo
Pueblo
Pueblo is a term used to describe modern communities of Native Americans in the Southwestern United States of America. The first Spanish explorers of the Southwest used this term to describe the communities housed in apartment-like structures built of stone, adobe mud, and other local material...
s in the American Southwest
Southwestern United States
The Southwestern United States is a region defined in different ways by different sources. Broad definitions include nearly a quarter of the United States, including Arizona, California, Colorado, Nevada, New Mexico, Oklahoma, Texas and Utah...
. The park is located in northwestern New Mexico, between Albuquerque
Albuquerque, New Mexico
Albuquerque is the largest city in the state of New Mexico, United States. It is the county seat of Bernalillo County and is situated in the central part of the state, straddling the Rio Grande. The city population was 545,852 as of the 2010 Census and ranks as the 32nd-largest city in the U.S. As...
and Farmington
Farmington, New Mexico
Farmington is a city in San Juan County in the U.S. state of New Mexico. As of the 2010 U.S. Census the city had a total population of 45,877 people. Farmington makes up one of the four Metropolitan Statistical Areas in New Mexico. The U.S...
, in a remote canyon cut by the Chaco Wash
Chaco Wash
The Chaco Wash is an arroyo cutting through Chaco Canyon, which is located in northwestern New Mexico on the Colorado Plateau. Another arroyo known as Escavada Wash is a tributary that feeds in from the northeast, near the western end of Chaco Canyon. Chaco Wash flows northwest to become the...
. Containing the most sweeping collection of ancient ruins north of Mexico, the park preserves one of the United States' most important pre-Columbian
Pre-Columbian
The pre-Columbian era incorporates all period subdivisions in the history and prehistory of the Americas before the appearance of significant European influences on the American continents, spanning the time of the original settlement in the Upper Paleolithic period to European colonization during...
cultural and historical areas.
Between AD 900 and 1150, Chaco Canyon was a major center of culture for the Ancient Pueblo Peoples
Ancient Pueblo Peoples
Ancient Pueblo People or Ancestral Pueblo peoples were an ancient Native American culture centered on the present-day Four Corners area of the United States, comprising southern Utah, northern Arizona, northwest New Mexico, and southern Colorado...
. Chacoans quarried sandstone blocks and hauled timber from great distances, assembling fifteen major complexes which remained the largest buildings in North America until the 19th century. Evidence of archaeoastronomy
Archaeoastronomy
Archaeoastronomy is the study of how people in the past "have understood the phenomena in the sky how they used phenomena in the sky and what role the sky played in their cultures." Clive Ruggles argues it is misleading to consider archaeoastronomy to be the study of ancient astronomy, as modern...
at Chaco has been proposed, with the "Sun Dagger" petroglyph at Fajada Butte
Fajada Butte
Fajada Butte is in Chaco Culture National Historical Park, in northwest New Mexico.Fajada Butte rises 135 meters above the canyon floor. Although there is no water source on the butte, there are ruins of small cliff dwellings in the higher regions of the butte...
a popular example. Many Chacoan buildings may have been aligned to capture the solar and lunar cycles, requiring generations of astronomical observations and centuries of skillfully coordinated construction. Climate change is thought to have led to the emigration of Chacoans and the eventual abandonment of the canyon, beginning with a fifty-year drought commencing in 1130.
Composing a UNESCO
UNESCO
The United Nations Educational, Scientific and Cultural Organization is a specialized agency of the United Nations...
World Heritage Site
World Heritage Site
A UNESCO World Heritage Site is a place that is listed by the UNESCO as of special cultural or physical significance...
located in the arid and sparsely populated Four Corners region, the Chacoan cultural sites are fragile; fears of erosion caused by tourists have led to the closure of Fajada Butte to the public. The sites are considered sacred ancestral homelands by the Hopi
Hopi
The Hopi are a federally recognized tribe of indigenous Native American people, who primarily live on the Hopi Reservation in northeastern Arizona. The Hopi area according to the 2000 census has a population of 6,946 people. Their Hopi language is one of the 30 of the Uto-Aztecan language...
and Pueblo people
Pueblo people
The Pueblo people are a Native American people in the Southwestern United States. Their traditional economy is based on agriculture and trade. When first encountered by the Spanish in the 16th century, they were living in villages that the Spanish called pueblos, meaning "towns". Of the 21...
, who maintain oral accounts of their historical migration from Chaco and their spiritual relationship to the land. Though park preservation efforts can conflict with native religious beliefs, tribal representatives work closely with the National Park Service to share their knowledge and respect the heritage of the Chacoan culture.
Geography
Chaco Canyon lies within the San Juan BasinSan Juan Basin
The San Juan Basin is a geologic structural basin in the Four Corners region of the Southwestern United States; its main portion covers around , encompassing much of northwestern New Mexico, southwest Colorado, and parts of Arizona and Utah....
, atop the vast Colorado Plateau
Colorado Plateau
The Colorado Plateau, also called the Colorado Plateau Province, is a physiographic region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. The province covers an area of 337,000 km2 within western Colorado, northwestern New Mexico,...
, surrounded by the Chuska Mountains
Chuska mountains
The Chuska Mountains are an elongate range on the Colorado Plateau and within the Navajo Nation. The range is about 80 by 15 km , and it trends north-northwest and is crossed by the state line between Arizona and New Mexico. The highlands are a dissected plateau, with an average elevation of...
in the west, the San Juan Mountains
San Juan Mountains
The San Juan Mountains are a high and rugged mountain range in the Rocky Mountains in southwestern Colorado. The area is highly mineralized and figured in the gold and silver mining industry of early Colorado. Major towns, all old mining camps, include Creede, Lake City, Silverton, Ouray, and...
to the north, and the San Pedro Mountains in the east. Ancient Chacoans drew upon dense forests of oak
Oak
An oak is a tree or shrub in the genus Quercus , of which about 600 species exist. "Oak" may also appear in the names of species in related genera, notably Lithocarpus...
, piñon
Pinyon pine
The pinyon pine group grows in the southwestern United States and in Mexico. The trees yield edible pinyon nuts, which were a staple of the Native Americans, and are still widely eaten...
, ponderosa pine
Ponderosa Pine
Pinus ponderosa, commonly known as the Ponderosa Pine, Bull Pine, Blackjack Pine, or Western Yellow Pine, is a widespread and variable pine native to western North America. It was first described by David Douglas in 1826, from eastern Washington near present-day Spokane...
, and juniper
Juniper
Junipers are coniferous plants in the genus Juniperus of the cypress family Cupressaceae. Depending on taxonomic viewpoint, there are between 50-67 species of juniper, widely distributed throughout the northern hemisphere, from the Arctic, south to tropical Africa in the Old World, and to the...
to obtain timber and other resources. The canyon itself, located within lowlands circumscribed by dune fields, ridges, and mountains, is aligned along a roughly northwest-to-southeast axis and is rimmed by flat massifs known as mesa
Mesa
A mesa or table mountain is an elevated area of land with a flat top and sides that are usually steep cliffs. It takes its name from its characteristic table-top shape....
s. Large gaps between the southwestern cliff faces—side canyons known as rincons—were critical in funneling rain-bearing storms into the canyon and boosting local precipitation levels. The principal Chacoan complexes, such as Pueblo Bonito
Pueblo Bonito
Pueblo Bonito, the largest and best known Great House in Chaco Culture National Historical Park, northern New Mexico, was built by ancestral Pueblo people and occupied between AD 828 and 1126....
, Nuevo Alto
Nuevo Alto
Nuevo Alto is a Chacoan Anasazi great house and notable archaeological site located in Chaco Canyon, a canyon in the U.S. state of New Mexico. It was built on the north mesa near Pueblo Alto, and was founded in the late 12th century, a time when the Chacoan population was declining in the canyon;...
, and Kin Kletso
Kin Kletso
Kin Kletso is a Chacoan Anasazi great house and notable archaeological site located in Chaco Culture National Historical Park, located 25 miles southwest of Nageezi, New Mexico, U.S....
, have elevations of 6200 foot.
The alluvial
Alluvium
Alluvium is loose, unconsolidated soil or sediments, eroded, deposited, and reshaped by water in some form in a non-marine setting. Alluvium is typically made up of a variety of materials, including fine particles of silt and clay and larger particles of sand and gravel...
canyon floor slopes downward to the northeast at a gentle grade of 30 feet (9.1 m) per mile (6meters per kilometer); it is bisected by the Chaco Wash
Chaco Wash
The Chaco Wash is an arroyo cutting through Chaco Canyon, which is located in northwestern New Mexico on the Colorado Plateau. Another arroyo known as Escavada Wash is a tributary that feeds in from the northeast, near the western end of Chaco Canyon. Chaco Wash flows northwest to become the...
, an arroyo
Arroyo (creek)
An arroyo , a Spanish word translated as brook, and also called a wash is usually a dry creek or stream bed—gulch that temporarily or seasonally fills and flows after sufficient rain. Wadi is a similar term in Africa. In Spain, a rambla has a similar meaning to arroyo.-Types and processes:Arroyos...
that rarely bears water. The canyon's main aquifer
Aquifer
An aquifer is a wet underground layer of water-bearing permeable rock or unconsolidated materials from which groundwater can be usefully extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology...
s were too deep to be of use to ancient Chacoans: only several smaller and shallower sources supported the small springs that sustained them. Aside from occasional storm runoff coursing through arroyos, substantial surface water—springs, pools, wells—is virtually non-existent.
Geology
After the PangaeaPangaea
Pangaea, Pangæa, or Pangea is hypothesized as a supercontinent that existed during the Paleozoic and Mesozoic eras about 250 million years ago, before the component continents were separated into their current configuration....
n supercontinent sundered during the Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
period, the region became part of a shifting transition zone between a shallow inland sea—the Western Interior Seaway
Western Interior Seaway
The Western Interior Seaway, also called the Cretaceous Seaway, the Niobraran Sea, and the North American Inland Sea, was a huge inland sea that split the continent of North America into two halves, Laramidia and Appalachia, during most of the mid- and late-Cretaceous Period...
—and a band of plains and low hills to the west. A sandy and swampy coastline oscillated east and west, alternately submerging and uncovering the area atop the present Colorado Plateau that Chaco Canyon now occupies.
As the Chaco Wash flowed across the upper strata of what is now the 400 feet (121.9 m) Chacra Mesa
Chacra Mesa
The Chacra Mesa is a high mesa massif composing the southwestern flank of Chaco Canyon, a region that is notable for its rich collection of ancient Chacoan Anasazi archaeological sites....
, it cut into it, gouging out a broad canyon over the course of millions of years. The mesa comprises sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
and shale
Shale
Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...
formations dating from the Late Cretaceous
Late Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
, which are of the Mesa Verde formation
Geologic formation
A formation or geological formation is the fundamental unit of lithostratigraphy. A formation consists of a certain number of rock strata that have a comparable lithology, facies or other similar properties...
. The canyon bottomlands were further eroded, exposing Menefee Shale
Menefee Shale
The Menefee Shale is a geological stratum underlying the Chaco Wash, which is located in the northwestern portion of the U.S. state of New Mexico, in what is now Chaco Culture National Historical Park...
bedrock
Bedrock
In stratigraphy, bedrock is the native consolidated rock underlying the surface of a terrestrial planet, usually the Earth. Above the bedrock is usually an area of broken and weathered unconsolidated rock in the basal subsoil...
; this was subsequently buried under roughly 125 feet (38.1 m) of sediment
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
. The canyon and mesa lie within the "Chaco Core", distinct from the wider Chaco Plateau, the latter a flat region of grassland with infrequent stands of timber. As the Continental Divide
Continental Divide
The Continental Divide of the Americas, or merely the Continental Gulf of Division or Great Divide, is the name given to the principal, and largely mountainous, hydrological divide of the Americas that separates the watersheds that drain into the Pacific Ocean from those river systems that drain...
is only 15.5 miles (25 km) east of the canyon, geological characteristics and different patterns of drainage differentiate these two regions both from each other and from the nearby Chaco Slope
Chaco Slope
The Chaco Slope is a geographical region located in the northwestern portion of the U.S. state of New Mexico. It borders the Chaco Core, which contains both Chacra Mesa and Chaco Canyon. The canyon itself is noted for its Chacoan Anasazi ruins...
, the Gobernador Slope
Gobernador Slope
The Gobernador Slope is a geographical region located in the northwestern portion of the U.S. state of New Mexico. It is near both Chacra Mesa and Chaco Canyon, which are noted for their Chacoan Anasazi ruins. The Chaco Slope is differentiated from the neighboring Chuska Valley, Chaco Core and...
, and the Chuska Valley
Chuska Valley
The Chuska Valley is a geographical region located in the northwestern portion of the U.S. state of New Mexico. Sitting atop the Colorado Plateau in the Four Corners region of the desert Southwest, it is near both Chacra Mesa and Chaco Canyon, which are noted for their Chacoan Anasazi ruins...
.
Climate
An arid region of high xeric scrublandDeserts and xeric shrublands
Deserts and xeric shrublands is a biome characterized by, relating to, or requiring only a small amount of moisture.-Definition and occurrence:...
and desert steppe, the canyon and wider basin average 8 inches (203.2 mm) of rainfall annually; the park averages 9.1 inches (231.1 mm). Chaco Canyon lies on the leeward side of extensive mountain ranges to the south and west, resulting in a rainshadow effect that fosters the prevailing lack of moisture in the region. The region sees four distinct seasons. Rainfall is most likely between July and September; May and June are the driest months. Orographic precipitation, which results from moisture wrung out of storm systems ascending the mountain ranges around Chaco Canyon, is responsible for most of the summer and winter precipitation; rainfall increases with higher elevation. Occasional aberrant northward excursions of the intertropical convergence zone
Intertropical Convergence Zone
The Intertropical Convergence Zone , known by sailors as The Doldrums, is the area encircling the earth near the equator where winds originating in the northern and southern hemispheres come together....
may boost precipitation in some years.
Chaco endures remarkable climatic extremes: temperatures range between -38 F, and may swing 60°F (33°C) in one day. The region averages less than 150frost-free days per year, and the local climate swings wildly from years of plentiful rainfall to prolonged drought. The heavy influence of the El Niño-Southern Oscillation
El Niño-Southern Oscillation
El Niño/La Niña-Southern Oscillation, or ENSO, is a quasiperiodic climate pattern that occurs across the tropical Pacific Ocean roughly every five years...
contributes to the canyon's fickle climate.
Flora and fauna
Chacoan flora typifies that of North American high deserts: sagebrushArtemisia tridentata
Artemisia tridentata is a shrub or small tree from the family Asteraceae. Some botanists treat it in the segregate genus Seriphidium, as S. tridentatum W. A. Weber, but this is not widely followed...
and several species of cactus
Cactus
A cactus is a member of the plant family Cactaceae. Their distinctive appearance is a result of adaptations to conserve water in dry and/or hot environments. In most species, the stem has evolved to become photosynthetic and succulent, while the leaves have evolved into spines...
are interspersed with dry scrub forests of piñon
Pinyon pine
The pinyon pine group grows in the southwestern United States and in Mexico. The trees yield edible pinyon nuts, which were a staple of the Native Americans, and are still widely eaten...
and juniper
Juniper
Junipers are coniferous plants in the genus Juniperus of the cypress family Cupressaceae. Depending on taxonomic viewpoint, there are between 50-67 species of juniper, widely distributed throughout the northern hemisphere, from the Arctic, south to tropical Africa in the Old World, and to the...
, the latter primarily on the mesa tops. The canyon is far drier than other parts of New Mexico located at similar latitudes and elevations, and it lacks the temperate coniferous forests
Temperate coniferous forests
Temperate coniferous forest is a terrestrial biome found in temperate regions of the world with warm summers and cool winters and adequate rainfall to sustain a forest. In most temperate coniferous forests, evergreen conifers predominate, while some are a mix of conifers and broadleaf evergreen...
plentiful to the east. The prevailing sparseness of plants and wildlife was echoed in ancient times, when overpopulation, expanding cultivation, overhunting, habitat destruction, and drought may have led the Chacoans to strip the canyon of wild plants and game. It has been suggested that even during wet periods the canyon was able to sustain only 2,000 people.
Among Chacoan mammals are the plentiful coyote
Coyote
The coyote , also known as the American jackal or the prairie wolf, is a species of canine found throughout North and Central America, ranging from Panama in the south, north through Mexico, the United States and Canada...
(Canis latrans); mule deer
Mule Deer
The mule deer is a deer indigenous to western North America. The Mule Deer gets its name from its large mule-like ears. There are believed to be several subspecies, including the black-tailed deer...
, elk
Elk
The Elk is the large deer, also called Cervus canadensis or wapiti, of North America and eastern Asia.Elk may also refer to:Other antlered mammals:...
, and pronghorn
Pronghorn
The pronghorn is a species of artiodactyl mammal endemic to interior western and central North America. Though not an antelope, it is often known colloquially in North America as the prong buck, pronghorn antelope, or simply antelope, as it closely resembles the true antelopes of the Old World and...
also live within the canyon, though they are rarely encountered by visitors. Important smaller carnivores include bobcat
Bobcat
The bobcat is a North American mammal of the cat family Felidae, appearing during the Irvingtonian stage of around 1.8 million years ago . With twelve recognized subspecies, it ranges from southern Canada to northern Mexico, including most of the continental United States...
s, badger
Badger
Badgers are short-legged omnivores in the weasel family, Mustelidae. There are nine species of badger, in three subfamilies : Melinae , Mellivorinae , and Taxideinae...
s, fox
Fox
Fox is a common name for many species of omnivorous mammals belonging to the Canidae family. Foxes are small to medium-sized canids , characterized by possessing a long narrow snout, and a bushy tail .Members of about 37 species are referred to as foxes, of which only 12 species actually belong to...
es, and two species of skunk
Skunk
Skunks are mammals best known for their ability to secrete a liquid with a strong, foul odor. General appearance varies from species to species, from black-and-white to brown or cream colored. Skunks belong to the family Mephitidae and to the order Carnivora...
. The park hosts abundant populations of rodents, including several prairie dog
Prairie dog
Prairie dogs are burrowing rodents native to the grasslands of North America. There are five different species of prairie dogs: black-tailed, white-tailed, Gunnison's, Utah and Mexican prairie dogs. They are a type of ground squirrel, found in the United States, Canada and Mexico...
towns. Small colonies of bat
Bat
Bats are mammals of the order Chiroptera "hand" and pteron "wing") whose forelimbs form webbed wings, making them the only mammals naturally capable of true and sustained flight. By contrast, other mammals said to fly, such as flying squirrels, gliding possums, and colugos, glide rather than fly,...
s, are present during the summer. The local shortage of water means that relatively few bird species are present; these include roadrunners
Geococcyx
The roadrunners are two species of bird in the genus Geococcyx of the cuckoo family, Cuculidae, native to North and Central America...
, large hawk
Hawk
The term hawk can be used in several ways:* In strict usage in Australia and Africa, to mean any of the species in the subfamily Accipitrinae, which comprises the genera Accipiter, Micronisus, Melierax, Urotriorchis and Megatriorchis. The large and widespread Accipiter genus includes goshawks,...
s (such as Cooper's hawk
Cooper's Hawk
Cooper's Hawk is a medium-sized hawk native to the North American continent and found from Canada to Mexico. As in many birds of prey, the male is smaller than the female...
s and American kestrel
American Kestrel
The American Kestrel , sometimes colloquially known as the Sparrow Hawk, is a small falcon, and the only kestrel found in the Americas. It is the most common falcon in North America, and is found in a wide variety of habitats. At long, it is also the smallest falcon in North America...
s), owl
Owl
Owls are a group of birds that belong to the order Strigiformes, constituting 200 bird of prey species. Most are solitary and nocturnal, with some exceptions . Owls hunt mostly small mammals, insects, and other birds, although a few species specialize in hunting fish...
s, vulture
Vulture
Vulture is the name given to two groups of convergently evolved scavenging birds, the New World Vultures including the well-known Californian and Andean Condors, and the Old World Vultures including the birds which are seen scavenging on carcasses of dead animals on African plains...
s, and raven
Raven
Raven is the common name given to several larger-bodied members of the genus Corvus—but in Europe and North America the Common Raven is normally implied...
s, though they are less abundant in the canyon than in the wetter mountain ranges to the east. Sizeable populations of smaller birds, including warblers
New World warbler
The New World warblers or wood-warblers are a group of small, often colorful, passerine birds restricted to the New World. They are not related to the Old World warblers or the Australian warblers....
, sparrow
Sparrow
The sparrows are a family of small passerine birds, Passeridae. They are also known as true sparrows, or Old World sparrows, names also used for a genus of the family, Passer...
s, and house finches
House Finch
The House Finch is a bird in the finch family Fringillidae, which is found in North America. This species and the other "American rosefinches" are usually placed in the rosefinch genus Carpodacus...
, are also common. Three species of hummingbird
Hummingbird
Hummingbirds are birds that comprise the family Trochilidae. They are among the smallest of birds, most species measuring in the 7.5–13 cm range. Indeed, the smallest extant bird species is a hummingbird, the 5-cm Bee Hummingbird. They can hover in mid-air by rapidly flapping their wings...
s are present: one is the tiny but highly pugnacious rufous hummingbird
Rufous Hummingbird
The Rufous Hummingbird is a small hummingbird, about 8 cm long with a long, straight and very slender bill. The female is slightly larger than the male.-Description:...
, which compete intensely with the more mild-tempered black-chinned hummingbird
Black-chinned Hummingbird
The Black-chinned Hummingbird is a small hummingbird.Adults are metallic green above and white below with green flanks. Their bill is long, straight and very slender. The adult male has a black face and chin, a glossy purple throat band and a dark forked tail...
s for breeding habitat in shrubs or trees located near water. Western (prairie) rattlesnakes
Crotalus oreganus
Crotalus oreganus is a venomous pitviper species found in North America in the western United States, parts of British Columbia and northwestern Mexico. Seven subspecies are currently recognized, including the nominate subspecies described here....
are occasionally seen in the backcountry, though various lizards and skink
Skink
Skinks are lizards belonging to the family Scincidae. Together with several other lizard families, including Lacertidae , they comprise the superfamily or infraorder Scincomorpha...
s are far more abundant.
Archaic–Early Basketmakers
The first people in the San Juan BasinSan Juan Basin
The San Juan Basin is a geologic structural basin in the Four Corners region of the Southwestern United States; its main portion covers around , encompassing much of northwestern New Mexico, southwest Colorado, and parts of Arizona and Utah....
were hunter-gatherers: the Archaic–Early Basketmaker
Archaic–Early Basketmaker Era
The Archaic–Early Basketmaker Era, 7000 - 1500 BC was an Archaic cultural period of ancestors to the Ancient Pueblo People. They were distinguished from other Archaic people of the Southwest by their basketry which was used to gather and store food...
people. These small bands descended from nomadic Clovis
Clovis culture
The Clovis culture is a prehistoric Paleo-Indian culture that first appears 11,500 RCYBP , at the end of the last glacial period, characterized by the manufacture of "Clovis points" and distinctive bone and ivory tools...
big-game hunters who arrived in the Southwest around 10,000 BC. More than 70 campsites from this period, carbon-dated to the period 7000–1500 BC and mostly consisting of stone chips and other leavings, were found in Atlatl Cave and elsewhere within Chaco Canyon, with at least one of the sites located on the canyon floor near an exposed arroyo. The Archaic–Early Basketmaker people were nomadic or semi-nomadic hunter-gatherer
Hunter-gatherer
A hunter-gatherer or forage society is one in which most or all food is obtained from wild plants and animals, in contrast to agricultural societies which rely mainly on domesticated species. Hunting and gathering was the ancestral subsistence mode of Homo, and all modern humans were...
s who over time began making baskets to store gathered plants. By the end of the period, some people cultivated food. Excavation of their campsites and rock shelters has revealed that they made tools, gathered wild plants, and killed and processed game. Slab-lined storage cisterns indicate a change from a wholly nomadic lifestyle.
Ancestral Puebloans
Late Basketmaker II Era
The Late Basketmaker II Era was a cultural period of Ancient Pueblo People when people began living in pit-houses, raised maize and squash, and were proficient basket makers and weavers...
, farmed lands around Shabik'eshchee Village and other pit-house
Pit-house
A pit-house is a dwelling dug into the ground which may also be layered with stone.These structures may be used as places to tell stories, dance, sing, celebrate, and store food. In archaeology, pit-houses are also termed sunken featured buildings and are found in numerous cultures around the world...
settlements at Chaco.
A small population of Basketmaker
Basketmaker (culture)
The Basketmaker culture of the Ancient Pueblo People began about 1500 BC and continued until about AD 500 with the beginning of the Pueblo I Era...
s remained in the Chaco Canyon area. The broad arc of their cultural elaboration culminated around 800, during the Pueblo I Era
Pueblo I Era
The Pueblo I Era, from AD 750 to 900, was the first period in which Ancient Pueblo People began living in pueblo structures and realized an evolution in architecture, artistic expression, and water conservation...
, when they were building crescent-shaped stone complexes, each comprising four to five residential suites abutting subterranean kiva
Kiva
A kiva is a room used by modern Puebloans for religious rituals, many of them associated with the kachina belief system. Among the modern Hopi and most other Pueblo peoples, kivas are square-walled and underground, and are used for spiritual ceremonies....
s, large enclosed areas reserved for rites. Such structures characterize the Early Pueblo People
Pecos Classification
The Pecos Classification is a division of all known Ancient Pueblo Peoples culture into chronological phases, based on changes in architecture, art, pottery, and cultural remains. The original classification dates back to consensus reached at a 1927 archæological conference held in Pecos, New...
. By 850, the Ancient Pueblo population—the "Anasazi", from a Ute
Ute Tribe
The Ute are an American Indian people now living primarily in Utah and Colorado. There are three Ute tribal reservations: Uintah-Ouray in northeastern Utah ; Southern Ute in Colorado ; and Ute Mountain which primarily lies in Colorado, but extends to Utah and New Mexico . The name of the state of...
term adopted by the Navajo
Navajo language
Navajo or Navaho is an Athabaskan language spoken in the southwestern United States. It is geographically and linguistically one of the Southern Athabaskan languages .Navajo has more speakers than any other Native American language north of the...
denoting the "ancient ones" or "enemy ancestors"—had rapidly expanded: groups resided in larger, denser pueblos. Strong evidence attests to a canyon-wide turquoise processing and trading industry dating from the 10th century. Around then, the first section of Pueblo Bonito
Pueblo Bonito
Pueblo Bonito, the largest and best known Great House in Chaco Culture National Historical Park, northern New Mexico, was built by ancestral Pueblo people and occupied between AD 828 and 1126....
was built: a curved row of 50 rooms near its present north wall.
The cohesive Chacoan system began unravelling around 1140, perhaps triggered by an extreme fifty-year drought that began in 1130; chronic climatic instability, including a series of severe droughts, again struck the region between 1250 and 1450. Poor water management lead to arroyo cutting; deforestation was extensive and economically devastating: timber for construction had to instead be hauled from outlying mountain ranges such as the Chuska Mountains
Chuska mountains
The Chuska Mountains are an elongate range on the Colorado Plateau and within the Navajo Nation. The range is about 80 by 15 km , and it trends north-northwest and is crossed by the state line between Arizona and New Mexico. The highlands are a dissected plateau, with an average elevation of...
, which are over 50 miles (80.5 km) to the west. Outlying communities began to depopulate and, by the end of the century, the buildings in the central canyon had been neatly sealed and abandoned.
Some scholars suggest that violence and warfare, perhaps involving cannibalism, impelled the evacuations. Hints of such include dismembered bodies—dating from Chacoan times—found at two sites within the central canyon. Yet Chacoan complexes showed little evidence of being defended or defensively sited high on cliff faces or atop mesas, and only several minor sites at Chaco evidence the large-scale burning that would suggest enemy raids. Archaeological and cultural evidence leads scientists to believe people from this region migrated south, east, and west into the valleys and drainages of the Little Colorado River
Little Colorado River
The Little Colorado River is a river in the U.S. state of Arizona, providing the principal drainage from the Painted Desert region. Together with its major tributary, the Puerco River, it drains an area of about in eastern Arizona and western New Mexico...
, the Rio Puerco, and the Rio Grande
Rio Grande
The Rio Grande is a river that flows from southwestern Colorado in the United States to the Gulf of Mexico. Along the way it forms part of the Mexico – United States border. Its length varies as its course changes...
. Anthropologist Joseph Tainter
Joseph Tainter
Joseph A. Tainter is a U.S. anthropologist and historian.Tainter studied anthropology at the University of California and Northwestern University, where he received his Ph.D. in 1975. He is currently a professor in the Department of Environment and Society at Utah State University...
deals at length with the structure and decline of Chaco civilization in his 1988 study The Collapse of Complex Societies.
Athabaskan succession
Numic-speaking peoples, such as the UteUte Tribe
The Ute are an American Indian people now living primarily in Utah and Colorado. There are three Ute tribal reservations: Uintah-Ouray in northeastern Utah ; Southern Ute in Colorado ; and Ute Mountain which primarily lies in Colorado, but extends to Utah and New Mexico . The name of the state of...
and Shoshone
Shoshone
The Shoshone or Shoshoni are a Native American tribe in the United States with three large divisions: the Northern, the Western and the Eastern....
, were present on the Colorado Plateau beginning in the 12th century. Nomadic Southern Athabaskan speaking peoples, such as the Apache
Apache
Apache is the collective term for several culturally related groups of Native Americans in the United States originally from the Southwest United States. These indigenous peoples of North America speak a Southern Athabaskan language, which is related linguistically to the languages of Athabaskan...
and Navajo
Navajo people
The Navajo of the Southwestern United States are the largest single federally recognized tribe of the United States of America. The Navajo Nation has 300,048 enrolled tribal members. The Navajo Nation constitutes an independent governmental body which manages the Navajo Indian reservation in the...
, succeeded the Pueblo people in this region by the 15th century; in the process, they acquired Chacoan customs and agricultural skills. Ute tribal groups also frequented the region, primarily during hunting and raiding expeditions. The modern Navajo Nation lies west of Chaco Canyon, and many Navajo live in surrounding areas. The arrival of the Spanish in the 17th century inaugurated an era of subjugation and rebellion, with the Chaco Canyon area absorbing Puebloan and Navajo refugees fleeing Spanish rule. In succession, as first Mexico, then the U.S., gained sovereignty over the canyon, military campaigns were launched against the region's remaining inhabitants.
Excavation and protection
The trader Josiah GreggJosiah Gregg
Josiah Gregg was a merchant, explorer, naturalist, and author of the American Southwest and Northern Mexico regions. He is most famous for his book Commerce of the Prairies.-Early years:...
was the first to write about the ruins of Chaco Canyon, referring in 1832 to Pueblo Bonito as "built of fine-grit sandstone". In 1849, a U.S. Army detachment passed through and surveyed the ruins. The canyon was so remote, however, that it was scarcely visited over the next 50 years. After brief reconnaissance work by Smithsonian scholars in the 1870s, formal archaeological work began in 1896 when a party from the American Museum of Natural History
American Museum of Natural History
The American Museum of Natural History , located on the Upper West Side of Manhattan in New York City, United States, is one of the largest and most celebrated museums in the world...
—the "Hyde Exploring Expedition"—began excavating Pueblo Bonito. Spending five summers in the region, they sent over 60,000 artifacts back to New York and operated a series of trading posts.
In 1901 Richard Wetherill
Richard Wetherill
Richard Wetherill , a member of a prominent Colorado ranching family, was an amateur explorer in the discovery, research and excavation of sites associated with the Ancient Pueblo People...
, who had worked for the Hyde expedition, claimed a homestead
Homestead Act
A homestead act is one of three United States federal laws that gave an applicant freehold title to an area called a "homestead" – typically 160 acres of undeveloped federal land west of the Mississippi River....
of 161 acres (65.2 ha) that included Pueblo Bonito, Pueblo del Arroyo
Pueblo del Arroyo
Pueblo del Arroyo is a Chacoan Anasazi great house and notable archaeological site located in Chaco Canyon, a canyon in the U.S. state of New Mexico. Founded between 1050 and 1075 AD and completed in the early 12th century, it is located near Pueblo Bonito at a drainage outlet known as South Gap....
, and Chetro Ketl
Chetro Ketl
Chetro Ketl is a Chacoan Anasazi great house and notable archaeological site located in Chaco Canyon, a canyon in the U.S. state of New Mexico. In the cliffs behind the ruins there are ancient stairways that lead to prehistoric roadways that connect to Pueblo Bonito...
. While investigating Wetherill's land claim, federal land agent Samuel J. Holsinger detailed the physical setting of the canyon and the sites, noted prehistoric road segments and stairways above Chetro Ketl, and documented prehistoric dams and irrigation systems. His report went unpublished and unheeded. It urged the creation of a national park to safeguard Chacoan sites. The next year, Edgar Lee Hewett
Edgar Lee Hewett
Edgar Lee Hewett, D.Sc., was an archaeologist/anthropologist active in work on the Native American communities of New Mexico and the southwestern United States, and most famous for his role in bringing about the Antiquities Act, a pioneering piece of legislation for the conservation movement...
, president of New Mexico Normal University (later renamed New Mexico Highlands University
New Mexico Highlands University
New Mexico Highlands University is a public university located in Las Vegas, New Mexico.-History:The university was first established as New Mexico Normal School in 1893, with the prominent archaeologist Edgar Lee Hewett serving as its first president...
), mapped many Chacoan sites. Hewett and others helped enact the Federal Antiquities Act of 1906
Antiquities Act
The Antiquities Act of 1906, officially An Act for the Preservation of American Antiquities , is an act passed by the United States Congress and signed into law by Theodore Roosevelt on June 8, 1906, giving the President of the United States authority to, by executive order, restrict the use of...
, the first U.S. law to protect relics; it was, in effect, a direct consequence of Wetherill's controversial activities at Chaco. The Act also authorized the President to found national monuments
U.S. National Monument
A National Monument in the United States is a protected area that is similar to a National Park except that the President of the United States can quickly declare an area of the United States to be a National Monument without the approval of Congress. National monuments receive less funding and...
: on March 11, 1907, Theodore Roosevelt proclaimed Chaco Canyon National Monument. Wetherill relinquished his claims.
In 1920, the National Geographic Society
National Geographic Society
The National Geographic Society , headquartered in Washington, D.C. in the United States, is one of the largest non-profit scientific and educational institutions in the world. Its interests include geography, archaeology and natural science, the promotion of environmental and historical...
began an archaeological examination of Chaco Canyon, and appointed Neil Judd
Neil Judd
Neil Merton Judd was an American archaeologist who studied under the pioneering archaeologist of the American Southwest, Edgar Lee Hewett. He was curator of archaeology at the erstwhile United States National Museum, which later became part of the Smithsonian Institution...
, then 32, to head the project. After a reconnaissance trip that year, Judd proposed to excavate Pueblo Bonito
Pueblo Bonito
Pueblo Bonito, the largest and best known Great House in Chaco Culture National Historical Park, northern New Mexico, was built by ancestral Pueblo people and occupied between AD 828 and 1126....
, the largest ruin at Chaco. Beginning in 1921, Judd spent seven field seasons at Chaco. Living and working conditions were spartan at best. In his memoirs, Judd noted dryly that "Chaco Canyon has its limitations as a summer resort". By 1925, Judd's excavators had removed 100,000 short tons of overburden
Overburden
Overburden is the material that lies above an area of economic or scientific interest in mining and archaeology; most commonly the rock, soil, and ecosystem that lies above a coal seam or ore body. It is also known as 'waste' or 'spoil'...
, using a team of "35 or more Indians, ten white men, and eight or nine horses". One puzzling discovery was that Judd's team only found 69 hearths in the ruin; winters are cold at Chaco. Judd sent A. E. Douglass
A. E. Douglass
A. E. Douglass was an American astronomer. He discovered a correlation between tree rings and the sunspot cycle....
more than 90 specimens for tree-ring dating, then in its infancy. At that time, Douglass had only a "floating" chronology. it was not until 1929 that a Judd-led team found the "missing link". Most of the beams used at Chaco were cut between 1033 and 1092, the height of construction there.
In 1949, the University of New Mexico
University of New Mexico
The University of New Mexico at Albuquerque is a public research university located in Albuquerque, New Mexico, in the United States. It is the state's flagship research institution...
deeded over adjoining lands to form an expanded Chaco Canyon National Monument. In return, the university maintained scientific research rights to the area. By 1959, the National Park Service
National Park Service
The National Park Service is the U.S. federal agency that manages all national parks, many national monuments, and other conservation and historical properties with various title designations...
had constructed a park visitor center, staff housing, and campgrounds. As a historic property of the National Park Service, the National Monument was listed on the National Register of Historic Places
National Register of Historic Places
The National Register of Historic Places is the United States government's official list of districts, sites, buildings, structures, and objects deemed worthy of preservation...
on October 15, 1966. In 1971, researchers Robert Lister and James Judge established the "Chaco Center", a division for cultural research that functioned as a joint project between the University of New Mexico and the National Park Service. A number of multi-disciplinary research projects, archaeological surveys, and limited excavations began during this time. The Chaco Center extensively surveyed the Chacoan roads, well-constructed and heavily built thoroughfares radiating from the central canyon. The results from such research conducted at Pueblo Alto and other sites dramatically altered accepted academic interpretations of both the Chacoan culture and the Four Corners region of the American Southwest.
The richness of the cultural remains at park sites led to the expansion of the small National Monument into the Chaco Culture National Historical Park on December 19, 1980, when an additional 13000 acres (5,260.9 ha) were added to the protected area. In 1987, the park was designated a World Heritage Site
World Heritage Site
A UNESCO World Heritage Site is a place that is listed by the UNESCO as of special cultural or physical significance...
by UNESCO
UNESCO
The United Nations Educational, Scientific and Cultural Organization is a specialized agency of the United Nations...
. To safeguard Chacoan sites on adjacent Bureau of Land Management
Bureau of Land Management
The Bureau of Land Management is an agency within the United States Department of the Interior which administers America's public lands, totaling approximately , or one-eighth of the landmass of the country. The BLM also manages of subsurface mineral estate underlying federal, state and private...
and Navajo Nation
Navajo Nation
The Navajo Nation is a semi-autonomous Native American-governed territory covering , occupying all of northeastern Arizona, the southeastern portion of Utah, and northwestern New Mexico...
lands, the Park Service developed the multi-agency Chaco Culture Archaeological Protection Site program. These initiatives have detailed the presence of more than 2,400 archeological sites within the current park's boundaries; only a small percentage of these have been excavated.
Management
Chaco Culture National Historical Park is managed by the National Park ServiceNational Park Service
The National Park Service is the U.S. federal agency that manages all national parks, many national monuments, and other conservation and historical properties with various title designations...
, a federal agency within the Department of the Interior; neighboring federal lands hosting Chacoan roads are controlled by the Bureau of Land Management
Bureau of Land Management
The Bureau of Land Management is an agency within the United States Department of the Interior which administers America's public lands, totaling approximately , or one-eighth of the landmass of the country. The BLM also manages of subsurface mineral estate underlying federal, state and private...
. In the 2002–2003 fiscal year, the park's total annual operating budget was 1,434,000. The park has a visitor center, which features the "Chaco Collection Museum", an information desk, a theater, a book store, and a gift shop. Prior to the 1980s, archeological excavations within current park boundaries were intensive: compound walls were dismantled or demolished, and thousands of artifacts were extracted. Starting in 1981, a new approach, informed by traditional Hopi and Pueblo beliefs, stopped such intrusions. Remote sensing
Remote sensing
Remote sensing is the acquisition of information about an object or phenomenon, without making physical contact with the object. In modern usage, the term generally refers to the use of aerial sensor technologies to detect and classify objects on Earth by means of propagated signals Remote sensing...
, anthropological study of Indian oral traditions, and dendrochronology—which left Chacoan relics undisturbed—were touted. In this vein, the "Chaco American Indian Consultation Committee" was established in 1991 to give Navajo, Hopi, Pueblo, and other Indian representatives a voice in park oversight.
Current park policy mandates partial restoration of excavated sites. "Backfilling", or re-burying excavated sites with sand, is one such means. Other measures attempt to safeguard the area's ancient ambiance and mystique: the "Chaco Night Sky Program", which seeks to eliminate the impact of light pollution
Light pollution
Light pollution, also known as photopollution or luminous pollution, is excessive or obtrusive artificial light.The International Dark-Sky Association defines light pollution as:...
on the park's acclaimed night skies; under the program, some 14,000 visitors make use of the Chaco Observatory (inaugurated in 1998), park telescopes, and astronomy-related programs. Chacoan relics outside the current park's boundaries have been threatened by development: an example was the proposed competitive leasing of federal lands in the San Juan Basin for surface coal mining beginning in 1983. As ample coal deposits abut the park, this strip mining threatened the web of ancient Chacoan roads. The year-long "Chaco Roads Project" thus documented the roads, which were later protected from mining.
Sites
The Chacoans built their complexes along a 9 mi (14 km) stretch of canyon floor, with the walls of some structures aligned cardinally and others aligned with the 18.6-year cycle of minimum and maximum moonrise and moonset. Nine Great Houses are positioned along the north side of Chaco Wash, at the base of massive sandstone mesas. Other Great Houses are found on mesa tops or in nearby washes and drainage areas. There are fourteen recognized Great Houses, which are grouped below according to geographic positioning with respect to the canyon.Central canyon
The central portion of the canyon contains the largest Chacoan complexes. The most studied is Pueblo BonitoPueblo Bonito
Pueblo Bonito, the largest and best known Great House in Chaco Culture National Historical Park, northern New Mexico, was built by ancestral Pueblo people and occupied between AD 828 and 1126....
; covering almost 2 acre (0.809372 ha) and comprising at least 650 rooms, it is the largest Great House; in parts of the complex, the structure was four stories high. The builders' use of core-and-veneer architecture and multi-story construction necessitated massive masonry walls up to 3 feet (91.4 cm) thick. Pueblo Bonito is divided into two sections by a wall precisely aligned to run north-south, bisecting the central plaza. A Great Kiva was placed on either side of the wall, creating a symmetrical pattern common to many Chacoan Great Houses. The scale of the complex, upon completion, rivaled that of the Colosseum.
Nearby is Pueblo del Arroyo
Pueblo del Arroyo
Pueblo del Arroyo is a Chacoan Anasazi great house and notable archaeological site located in Chaco Canyon, a canyon in the U.S. state of New Mexico. Founded between 1050 and 1075 AD and completed in the early 12th century, it is located near Pueblo Bonito at a drainage outlet known as South Gap....
. Founded between AD 1050 and 1075, completed in the early 12th century, it sits at a drainage outlet known as South Gap. Casa Rinconada, isolated from the other central sites, sits to the south side of Chaco Wash, adjacent to a Chacoan road leading to a set of steep stairs that reached the top of Chacra Mesa. Its sole kiva stands alone, with no residential or support structures whatever; it did once had a 39 feet (11.9 m) passageway leading from the underground kiva to several above-ground levels. Chetro Ketl
Chetro Ketl
Chetro Ketl is a Chacoan Anasazi great house and notable archaeological site located in Chaco Canyon, a canyon in the U.S. state of New Mexico. In the cliffs behind the ruins there are ancient stairways that lead to prehistoric roadways that connect to Pueblo Bonito...
, located near Pueblo Bonito, bears the typical 'D'-shape of many other central complexes, but is slightly smaller. Begun between AD 1020 and 1050, its 450–550 rooms shared one Great Kiva. Experts estimate that it took 29,135man-hours to erect Chetro Ketl alone; Hewett estimated that it took the wood of 5,000 trees and 50 million stone blocks.
Kin Kletso
Kin Kletso
Kin Kletso is a Chacoan Anasazi great house and notable archaeological site located in Chaco Culture National Historical Park, located 25 miles southwest of Nageezi, New Mexico, U.S....
("Yellow House") was a medium-sized complex located 0.5 miles (804.7 m) west of Pueblo Bonito. It shows strong evidence of construction and occupation by Pueblo peoples from the northern San Juan Basin. Its rectangular shape and design is related to the Pueblo II
Pueblo II Era
The Pueblo II Era, AD 900 to 1150, was the second pueblo period of the Ancient Pueblo People of the Four Corners region of the American southwest. During this period people lived in dwellings made of stone and mortar, enjoyed communal activities in kivas, built towers and water conversing dams,...
cultural group, rather than the Pueblo III style or its Chacoan variant. It contains 55 rooms, four ground-floor kivas, and a two-story cylindrical tower that may have functioned as a kiva or religious center. Evidence of an obsidian
Obsidian
Obsidian is a naturally occurring volcanic glass formed as an extrusive igneous rock.It is produced when felsic lava extruded from a volcano cools rapidly with minimum crystal growth...
-processing industry was discovered near the village, which was erected between AD 1125 and 1130.
Pueblo Alto
Pueblo Alto is a Chacoan Anasazi great house and archaeological site located in Chaco Canyon, northwestern New Mexico, United States. The complex, comprising 89 rooms in a single-story layout, is located on a mesa top near the middle of Chaco Canyon; 0.6 miles from Pueblo Bonito, it was...
is a Great House of 89 rooms located on a mesa top near the middle of Chaco Canyon, and is 0.6 mile (0.965604 km) from Pueblo Bonito; it was begun between AD 1020 and 1050 during a wider building boom throughout the canyon. Its location made the community visible to most of the inhabitants of the San Juan Basin; indeed, it was only 2.3 miles (3.7 km) north of Tsin Kletsin, on the opposite side of the canyon. The community was the center of a bead- and turquoise
Turquoise
Turquoise is an opaque, blue-to-green mineral that is a hydrous phosphate of copper and aluminium, with the chemical formula CuAl648·4. It is rare and valuable in finer grades and has been prized as a gem and ornamental stone for thousands of years owing to its unique hue...
-processing industry that influenced the development of all villages in the canyon; chert
Chert
Chert is a fine-grained silica-rich microcrystalline, cryptocrystalline or microfibrous sedimentary rock that may contain small fossils. It varies greatly in color , but most often manifests as gray, brown, grayish brown and light green to rusty red; its color is an expression of trace elements...
tool production was common. Research at the site conducted by archaeologist Tom Windes suggests only a handful of families, perhaps as few as five to twenty, lived in the complex; this may imply that Pueblo Alto served a primarily non-residential role. Another Great House, Nuevo Alto
Nuevo Alto
Nuevo Alto is a Chacoan Anasazi great house and notable archaeological site located in Chaco Canyon, a canyon in the U.S. state of New Mexico. It was built on the north mesa near Pueblo Alto, and was founded in the late 12th century, a time when the Chacoan population was declining in the canyon;...
, was built on the north mesa near Pueblo Alto; it was founded in the late 12th century, a time when the Chacoan population was declining.
Outliers
In Chaco's northern reaches lies another cluster of Great Houses; among the largest are Casa ChiquitaCasa Chiquita
Casa Chiquita is a Chacoan Anasazi great house and archaeological site located in Chaco Canyon, northwestern New Mexico, United States. Located near the old north entrance to the Canyon, its layout features a smaller profile with a square block of rooms surrounding a central elevated round room....
("Small House"), a village built in the AD 1080s, when, in a period of ample rainfall, Chacoan culture was expanding. Its layout featured a smaller, squarer profile; it also lacked the open plazas and separate kivas of its predecessors. Larger, squarer blocks of stone were used in the masonry; kivas were designed in the northern Mesa Verdean tradition. Two miles down the canyon is Peñasco Blanco
Peñasco Blanco
Peñasco Blanco is a Chacoan Anasazi great house and notable archaeological site located in Chaco Canyon, a canyon in San Juan County, New Mexico, United States.. It is an arc-shaped compound built atop the canyon's southern rim; it was constructed in five distinct stages between 900 AD and 1125 AD...
("White Bluff"), an arc-shaped compound built atop the canyon's southern rim in five distinct stages between AD 900 and 1125. A cliff painting (the "Supernova Platograph") nearby may record the sighting of the SN 1054
SN 1054
SN 1054 is a supernova that was first observed as a new "star" in the sky on July 4, 1054 AD, hence its name, and that lasted for a period of around two years. The event was recorded in multiple Chinese and Japanese documents and in one document from the Arab world...
supernova on July 5, 1054.
Hungo Pavi
Hungo Pavi
Hungo Pavi is a Chacoan Anasazi great house and archaeological site located in Chaco Canyon, northwestern New Mexico, United States. A set of ruins located just 1 mile from the ruins of Una Vida, Hungo Pavi measured 872 feet in circumference. Initial explorations revealed 72...
, located 1 mi (1.6 km) from Una Vida, measured 872 feet (265.8 m) in circumference. Initial probes revealed 72 ground-level rooms, with structures reaching four stories in height; one large circular kiva has been identified. Kin Nahasbas
Kin Nahasbas
Kin Nahasbas is a Chacoan Anasazi great house and archaeological site located in Chaco Canyon, 25 miles southwest of Nageezi, New Mexico, United States. Built in either the 9th or 10th centuries, it was major pueblo located slightly north of the Una Vida complex, which is positioned at the foot of...
, built in either the 9th or 10th century, is sited slightly north of Una Vida, positioned at the foot of the north mesa. Limited excavation of it has taken place. Tsin Kletzin
Tsin Kletzin
Tsin Kletzin or Tsin Kletsin is a Chacoan Anasazi archaeological site located on top of South Mesa in Chaco Culture National Historical Park, northwestern New Mexico, United States. It is located 3.2 kilometers south of Pueblo Bonito. Tree-ring dating placed the construction around 1110-1115 A.D...
("Charcoal Place"), a compound located on the Chacra Mesa and positioned above Casa Rinconada
Casa Rinconada
Casa Rinconada is a Chacoan Anasazi archaeological site located atop a ridge adjacent to a small rincon across from Pueblo Bonito in Chaco Culture National Historical Park, northwestern New Mexico, United States....
, is 2.3 miles (3.7 km) due south of Pueblo Alto, on the opposite side of the canyon. Nearby is Weritos Dam, a massive earthen structure that scientists believe provided Tsin Kletzin with all of its domestic water. The dam worked by retaining stormwater runoff in a reservoir. Massive amounts of silt accumulated during flash floods would have forced the residents to regularly rebuild the dam and dredge the catchment area.
Deeper in the canyon, Una Vida
Una Vida
Una Vida is an archaeological site located in Chaco Canyon, San Juan County, New Mexico, United States. Its construction began around 900 AD and it is one of the three earliest Chacoan Anasazi great houses; it...
("One Life") is one of the three oldest Great Houses; construction began around AD 900. Comprising at least two stories and 124 rooms, it shares an arc or "D"-shaped design with its contemporaries, Peñasco Blanco and Pueblo Bonito, but has a unique "dog leg" addition made necessary by topography. It is located in one of the canyon's major side drainages, near Gallo Wash, and was massively expanded after 930. Wijiji
Wijiji
Wijiji is a Chacoan Anasazi great house and notable archaeological site located in Chaco Canyon, a canyon in the U.S. state of New Mexico. Comprising just over 100 rooms, it is the smallest of the Chacoan great houses. Built between 1110 AD and 1115 AD, it was the last Chacoan great house to be...
("Greasewood
Greasewood
Greasewood, Sarcobatus, is a genus of one or two species of flowering plants. Traditionally it has been treated in the family Chenopodiaceae, but the APG II system, of 2003, places it in the family Sarcobataceae....
"), comprising just over one hundred rooms, is the smallest of the Great Houses. Built between AD 1110 and 1115, it was the last Chacoan Great House to be constructed. Somewhat isolated within the narrow wash, it is positioned 1 mi (1.6 km) from neighboring Una Vida. Directly north are communities even more remote: Salmon Ruins
Salmon Ruins
Salmon Ruins is a site in the far northwest of the American state of New Mexico hosting a Chacoan Anasazi great house built between approximately 1088 CE and 1100 CE. The complex contained around 150 ground-level rooms arranged into a D-shaped profile; up to 100 second-floor rooms are estimated to...
and Aztec Ruins, sited on the San Juan and Animas River
Animas River
Animas River is a river in the western United States, a tributary of the San Juan River, part of the Colorado River System. The Spanish named the river "Rio de las Animas Perdidas", "River of the Lost Souls". It is also the last free-flowing river in Colorado. The river's free-flowing status...
s near Farmington, were built during a thirty-year wet period commencing in AD 1100. Some 60 mi (97 km) directly south of Chaco Canyon, on the Great South Road, lies another cluster of outlying communities. The largest, Kin Nizhoni, stands atop a 7000 feet (2,133.6 m) mesa surrounded by marshy bottomlands.
"Great Houses"
Immense complexes known as "Great Houses" embodied worship at Chaco. The Chacoans used masonry techniques unique for their time, and their building constructions lasted decades and even centuries. As architectural forms evolved and centuries passed, the houses kept several core traits. Most apparent is their sheer bulk; complexes averaged more than 200 rooms each, and some enclosed up to 700 rooms. Individual rooms were substantial in size, with higher ceilings than Anasazi works of preceding periods. They were well-planned: vast sections or wings erected were finished in a single stage, rather than in increments. Houses generally faced the south, and plaza areas were almost always girt with edifices of sealed-off rooms or high walls. Houses often stood four or five stories tall, with single-story rooms facing the plaza; room blocks were terraced to allow the tallest sections to compose the pueblo's rear edifice. Rooms were often organized into suites, with front rooms larger than rear, interior, and storage rooms or areas.Ceremonial structures known as kiva
Kiva
A kiva is a room used by modern Puebloans for religious rituals, many of them associated with the kachina belief system. Among the modern Hopi and most other Pueblo peoples, kivas are square-walled and underground, and are used for spiritual ceremonies....
s were built in proportion to the number of rooms in a pueblo. One small kiva was built for roughly every 29 rooms. Nine complexes each hosted an oversized Great Kiva, each up to 63 feet (19.2 m) in diameter. "T"-shaped doorways and stone lintels marked all Chacoan kivas. Though simple and compound walls were often used, Great Houses were primarily constructed of core-and-veneer walls: two parallel load-bearing walls comprising dressed, flat sandstone blocks bound in clay mortar were erected. Gaps between walls were packed with rubble, forming the wall's core. Walls were then covered in a veneer of small sandstone pieces, which were pressed into a layer of binding mud. These surfacing stones were often placed in distinctive patterns. The Chacoan structures altogether required the wood of 200,000 coniferous trees, mostly hauled—on foot—from mountain ranges up to 70 miles (112.7 km) away.
Uses
The meticulously designed buildings composing the larger Chacoan complexes did not emerge until around AD 1030. The Chacoans melded pre-planned architectural designs, astronomical alignments, geometry, landscaping, and engineering into ancient urban centers of unique public architecture. Researchers have concluded that the complex may have had a relatively small residential population, with larger groups assembling only temporarily for annual ceremonies. Smaller sites, apparently more residential in character, are scattered near the Great Houses in and around Chaco. The canyon itself runs along one of the lunar alignment lines, suggesting the location was originally chosen for its astronomical significance. If nothing else, this allowed alignment with several other key structures in the canyon.
Around this time, the extended Ancestral Puebloan (Anasazi) community experienced a population and construction boom. Throughout the 10th century, Chacoan building techniques spread from the canyon to neighboring regions. By AD 1115 at least 70 outlying pueblos of Chacoan provenance had been built within the 25000 square miles (64,749.7 km²) composing the San Juan Basin. Experts speculate the function of these compounds, some large enough to be considered Great Houses in their own right. Some suggest they may have been more than agricultural communities, perhaps functioning as trading posts or ceremonial sites.
Thirty such outliers spread across 65000 square miles (168,349.2 km²) are connected to the central canyon and to one another by an enigmatic web of six Chacoan road systems. Extending up to 60 miles (96.6 km) in generally straight routes, they appear to have been extensively surveyed and engineered. Their depressed and scraped caliche
Caliche (Mineral)
Caliche is a sedimentary rock, a hardened deposit of calcium carbonate. This calcium carbonate cements together other materials, including gravel, sand, clay, and silt. It is found in aridisol and mollisol soil orders...
beds reach 30 feet (9.1 m) wide; earthen berms or rocks, at times composing low walls, delimit their edges. When necessary, the roads deploy steep stone stairways and rock ramps to surmount cliffs and other obstacles. Though their purpose may never be certain, archaeologist Harold Gladwin
Harold S. Gladwin
Harold Sterling Gladwin was an American archaeologist, anthropologist and stockbroker born in New York City.-Introduction:Harold Sterling Gladwin was an early twentieth century archaeologist that specialized in...
noted that nearby Navajo believe that the Anasazi built the roads to transport timber; archaeologist Neil Judd
Neil Judd
Neil Merton Judd was an American archaeologist who studied under the pioneering archaeologist of the American Southwest, Edgar Lee Hewett. He was curator of archaeology at the erstwhile United States National Museum, which later became part of the Smithsonian Institution...
offered a similar hypothesis.
"Sun Dagger"
Several parties have advanced the following contested theory: that at least twelve of the fourteen principal Chacoan complexes were sited and aligned in coordination, and that each was oriented along axes that mirrored the passing of the SunSun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
and Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
at visually pivotal times. Chaco's suspected role as a regional center of pilgrimage, where priestly elites staged the ritual smashing of pots—which over time built up at least one hillock composed solely of shards—is thought to underscore this pattern. Two whorl-shaped etchings near the top of Fajada Butte compose the "Sun Dagger" petroglyph, itself tucked behind the eponymous rock panels of the "Three-Slab Site". They are symbolically focal.
It consists of two spirals: one principal and one ancillary. The latter left-hand spiral captured both spring and fall equinoxes; its artifice was revealed by a descending spear of light, itself filtered through the slabs, that shined upon it and split it in two. The former and larger whorl to its right was lit by the titular "sun dagger", which bisected it through another interplay of slab and sun. It struck it, brilliantly, as the summer sun attains its solstice midday peak. The Chacoans were said to be marking, as artist, "Sun Dagger" discoverer, and leading proponent Anna Sofaer puts it, "the middle of time". Each turn of the 9.25-turn large spiral was found to mark one year in the 18.6-year "lunar excursion cycle" of the rising mid-winter full moon. This record is kept by a slab-cast lunar shadow whose edge strikes in succession each ring. As the full "minimum moon" closest to the winter solstice rises, the shadow's edge precisely strikes the center of the larger spiral; it steps outward year by year, ring by ring, until it strikes the outermost edge of it during the full "maximum moon", again in mid-winter.
Fajada Butte bears five other petroglyphs—including a carving of a "rattlesnake", other spirals, and a rectangle—that are conspicuously lit by contrasts between sunbeams and shadows during equinoxes or solstices. Public access to the butte was curtailed when, in 1989, erosion from modern foot traffic was found to be responsible for one of the three screening slabs at the "Sun Dagger" site shifting out of its ancient position; the assemblage of stones has thus lost some of its former spatial and temporal precision as a solar and lunar calendar. In 1990 the screens were stabilized and placed under observation, but the wayward slab was not moved back into its original orientation.
Alignments
The first Great House known to evince fastidious proportioning and alignment was Casa Rinconada: the twinned "T"-shaped portals of its 10 m (33 ft)-radius great kiva were north-south collinear, and axes joining opposing windows passed within 10 cm (4 in) of its center. The Great Houses of Pueblo Bonito and Chetro Ketl were found by the "Solstice Project" and the U.S. National Geodetic SurveyU.S. National Geodetic Survey
National Geodetic Survey, formerly called the U.S. Coast and Geodetic Survey , is a United States federal agency that defines and manages a national coordinate system, providing the foundation for transportation and communication; mapping and charting; and a large number of applications of science...
to be sited along a precisely east-west line, an axis that captures the passage of the equinox
Equinox
An equinox occurs twice a year, when the tilt of the Earth's axis is inclined neither away from nor towards the Sun, the center of the Sun being in the same plane as the Earth's equator...
sun. The lines perpendicularly bisecting their principal walls are aligned north-south, implying a possible intent to mirror the equinox midday. Pueblo Alto and Tsin Kletsin are also north-south aligned. These two axes form an inverted cross when viewed from above; its northbound reach is extended another 35 mi (56 km) past Pueblo Alto by the ramrod-straight "Great North Road", a pilgrimage route which modern-day Pueblo Indians believe to be an allusion to myths surrounding their arrival from the distant north.
Two shared-latitude but diametrically opposed complexes located some 15 mi (24 km) from the core buildings of the central canyon, Pueblo Pintado and Kin Bineola, each lie on a path from the central canyon that is collinear with the passage and setting of the full mid-winter "minimum moon", which recurs every 18.6 years. Two other complexes less distant from Pueblo Bonito, Una Vida and Peñasco Blanco, share an axis collinear with the passage of the full "maximum moon". The terms "minimum" and "maximum" refer to the azimuthal extreme points in the lunar excursion cycle, or the swings in direction relative to true north that the setting full moon exhibits. It takes roughly 9.25 years for the rising or setting full moon nearest to winter solstice
Solstice
A solstice is an astronomical event that happens twice each year when the Sun's apparent position in the sky, as viewed from Earth, reaches its northernmost or southernmost extremes...
to proceed from its maximum azimuthal north, or "maximum extremum", to its southernmost azimuth, known as "minimum extremum".
Reasons for the alignments have been offered:
See also
- Ah-Shi-Sle-Pah Wilderness Study AreaAh-Shi-Sle-Pah Wilderness Study AreaAh-Shi-Sle-Pah Wilderness Study Area is located in San Juan County, New Mexico between Chaco Canyon and the De-Na-Zin Wilderness. The Wilderness Study Area has multicolored badlands, sandstone hoodoos, petrified wood and dinosaur bones, similar to those found in the nearby Bisti Badlands and...
- List of archaeoastronomical sites by country
- List of dwellings of Pueblo peoples
Sources
}}}}
Chaco Culture National Historical Park is a United States National Historical Park
National Historic Sites (United States)
National Historic Sites are protected areas of national historic significance in the United States. A National Historic Site usually contains a single historical feature directly associated with its subject...
hosting the densest and most exceptional concentration of pueblo
Pueblo
Pueblo is a term used to describe modern communities of Native Americans in the Southwestern United States of America. The first Spanish explorers of the Southwest used this term to describe the communities housed in apartment-like structures built of stone, adobe mud, and other local material...
s in the American Southwest
Southwestern United States
The Southwestern United States is a region defined in different ways by different sources. Broad definitions include nearly a quarter of the United States, including Arizona, California, Colorado, Nevada, New Mexico, Oklahoma, Texas and Utah...
. The park is located in northwestern New Mexico, between Albuquerque
Albuquerque, New Mexico
Albuquerque is the largest city in the state of New Mexico, United States. It is the county seat of Bernalillo County and is situated in the central part of the state, straddling the Rio Grande. The city population was 545,852 as of the 2010 Census and ranks as the 32nd-largest city in the U.S. As...
and Farmington
Farmington, New Mexico
Farmington is a city in San Juan County in the U.S. state of New Mexico. As of the 2010 U.S. Census the city had a total population of 45,877 people. Farmington makes up one of the four Metropolitan Statistical Areas in New Mexico. The U.S...
, in a remote canyon cut by the Chaco Wash
Chaco Wash
The Chaco Wash is an arroyo cutting through Chaco Canyon, which is located in northwestern New Mexico on the Colorado Plateau. Another arroyo known as Escavada Wash is a tributary that feeds in from the northeast, near the western end of Chaco Canyon. Chaco Wash flows northwest to become the...
. Containing the most sweeping collection of ancient ruins north of Mexico, the park preserves one of the United States' most important pre-Columbian
Pre-Columbian
The pre-Columbian era incorporates all period subdivisions in the history and prehistory of the Americas before the appearance of significant European influences on the American continents, spanning the time of the original settlement in the Upper Paleolithic period to European colonization during...
cultural and historical areas.
Between AD 900 and 1150, Chaco Canyon was a major center of culture for the Ancient Pueblo Peoples
Ancient Pueblo Peoples
Ancient Pueblo People or Ancestral Pueblo peoples were an ancient Native American culture centered on the present-day Four Corners area of the United States, comprising southern Utah, northern Arizona, northwest New Mexico, and southern Colorado...
. Chacoans quarried sandstone blocks and hauled timber from great distances, assembling fifteen major complexes which remained the largest buildings in North America until the 19th century. Evidence of archaeoastronomy
Archaeoastronomy
Archaeoastronomy is the study of how people in the past "have understood the phenomena in the sky how they used phenomena in the sky and what role the sky played in their cultures." Clive Ruggles argues it is misleading to consider archaeoastronomy to be the study of ancient astronomy, as modern...
at Chaco has been proposed, with the "Sun Dagger" petroglyph at Fajada Butte
Fajada Butte
Fajada Butte is in Chaco Culture National Historical Park, in northwest New Mexico.Fajada Butte rises 135 meters above the canyon floor. Although there is no water source on the butte, there are ruins of small cliff dwellings in the higher regions of the butte...
a popular example. Many Chacoan buildings may have been aligned to capture the solar and lunar cycles, requiring generations of astronomical observations and centuries of skillfully coordinated construction. Climate change is thought to have led to the emigration of Chacoans and the eventual abandonment of the canyon, beginning with a fifty-year drought commencing in 1130.
Composing a UNESCO
UNESCO
The United Nations Educational, Scientific and Cultural Organization is a specialized agency of the United Nations...
World Heritage Site
World Heritage Site
A UNESCO World Heritage Site is a place that is listed by the UNESCO as of special cultural or physical significance...
located in the arid and sparsely populated Four Corners region, the Chacoan cultural sites are fragile; fears of erosion caused by tourists have led to the closure of Fajada Butte to the public. The sites are considered sacred ancestral homelands by the Hopi
Hopi
The Hopi are a federally recognized tribe of indigenous Native American people, who primarily live on the Hopi Reservation in northeastern Arizona. The Hopi area according to the 2000 census has a population of 6,946 people. Their Hopi language is one of the 30 of the Uto-Aztecan language...
and Pueblo people
Pueblo people
The Pueblo people are a Native American people in the Southwestern United States. Their traditional economy is based on agriculture and trade. When first encountered by the Spanish in the 16th century, they were living in villages that the Spanish called pueblos, meaning "towns". Of the 21...
, who maintain oral accounts of their historical migration from Chaco and their spiritual relationship to the land. Though park preservation efforts can conflict with native religious beliefs, tribal representatives work closely with the National Park Service to share their knowledge and respect the heritage of the Chacoan culture.
Geography
Chaco Canyon lies within the San Juan BasinSan Juan Basin
The San Juan Basin is a geologic structural basin in the Four Corners region of the Southwestern United States; its main portion covers around , encompassing much of northwestern New Mexico, southwest Colorado, and parts of Arizona and Utah....
, atop the vast Colorado Plateau
Colorado Plateau
The Colorado Plateau, also called the Colorado Plateau Province, is a physiographic region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. The province covers an area of 337,000 km2 within western Colorado, northwestern New Mexico,...
, surrounded by the Chuska Mountains
Chuska mountains
The Chuska Mountains are an elongate range on the Colorado Plateau and within the Navajo Nation. The range is about 80 by 15 km , and it trends north-northwest and is crossed by the state line between Arizona and New Mexico. The highlands are a dissected plateau, with an average elevation of...
in the west, the San Juan Mountains
San Juan Mountains
The San Juan Mountains are a high and rugged mountain range in the Rocky Mountains in southwestern Colorado. The area is highly mineralized and figured in the gold and silver mining industry of early Colorado. Major towns, all old mining camps, include Creede, Lake City, Silverton, Ouray, and...
to the north, and the San Pedro Mountains in the east. Ancient Chacoans drew upon dense forests of oak
Oak
An oak is a tree or shrub in the genus Quercus , of which about 600 species exist. "Oak" may also appear in the names of species in related genera, notably Lithocarpus...
, piñon
Pinyon pine
The pinyon pine group grows in the southwestern United States and in Mexico. The trees yield edible pinyon nuts, which were a staple of the Native Americans, and are still widely eaten...
, ponderosa pine
Ponderosa Pine
Pinus ponderosa, commonly known as the Ponderosa Pine, Bull Pine, Blackjack Pine, or Western Yellow Pine, is a widespread and variable pine native to western North America. It was first described by David Douglas in 1826, from eastern Washington near present-day Spokane...
, and juniper
Juniper
Junipers are coniferous plants in the genus Juniperus of the cypress family Cupressaceae. Depending on taxonomic viewpoint, there are between 50-67 species of juniper, widely distributed throughout the northern hemisphere, from the Arctic, south to tropical Africa in the Old World, and to the...
to obtain timber and other resources. The canyon itself, located within lowlands circumscribed by dune fields, ridges, and mountains, is aligned along a roughly northwest-to-southeast axis and is rimmed by flat massifs known as mesa
Mesa
A mesa or table mountain is an elevated area of land with a flat top and sides that are usually steep cliffs. It takes its name from its characteristic table-top shape....
s. Large gaps between the southwestern cliff faces—side canyons known as rincons—were critical in funneling rain-bearing storms into the canyon and boosting local precipitation levels. The principal Chacoan complexes, such as Pueblo Bonito
Pueblo Bonito
Pueblo Bonito, the largest and best known Great House in Chaco Culture National Historical Park, northern New Mexico, was built by ancestral Pueblo people and occupied between AD 828 and 1126....
, Nuevo Alto
Nuevo Alto
Nuevo Alto is a Chacoan Anasazi great house and notable archaeological site located in Chaco Canyon, a canyon in the U.S. state of New Mexico. It was built on the north mesa near Pueblo Alto, and was founded in the late 12th century, a time when the Chacoan population was declining in the canyon;...
, and Kin Kletso
Kin Kletso
Kin Kletso is a Chacoan Anasazi great house and notable archaeological site located in Chaco Culture National Historical Park, located 25 miles southwest of Nageezi, New Mexico, U.S....
, have elevations of 6200 foot.
The alluvial
Alluvium
Alluvium is loose, unconsolidated soil or sediments, eroded, deposited, and reshaped by water in some form in a non-marine setting. Alluvium is typically made up of a variety of materials, including fine particles of silt and clay and larger particles of sand and gravel...
canyon floor slopes downward to the northeast at a gentle grade of 30 feet (9.1 m) per mile (6meters per kilometer); it is bisected by the Chaco Wash
Chaco Wash
The Chaco Wash is an arroyo cutting through Chaco Canyon, which is located in northwestern New Mexico on the Colorado Plateau. Another arroyo known as Escavada Wash is a tributary that feeds in from the northeast, near the western end of Chaco Canyon. Chaco Wash flows northwest to become the...
, an arroyo
Arroyo (creek)
An arroyo , a Spanish word translated as brook, and also called a wash is usually a dry creek or stream bed—gulch that temporarily or seasonally fills and flows after sufficient rain. Wadi is a similar term in Africa. In Spain, a rambla has a similar meaning to arroyo.-Types and processes:Arroyos...
that rarely bears water. The canyon's main aquifer
Aquifer
An aquifer is a wet underground layer of water-bearing permeable rock or unconsolidated materials from which groundwater can be usefully extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology...
s were too deep to be of use to ancient Chacoans: only several smaller and shallower sources supported the small springs that sustained them. Aside from occasional storm runoff coursing through arroyos, substantial surface water—springs, pools, wells—is virtually non-existent.
Geology
After the PangaeaPangaea
Pangaea, Pangæa, or Pangea is hypothesized as a supercontinent that existed during the Paleozoic and Mesozoic eras about 250 million years ago, before the component continents were separated into their current configuration....
n supercontinent sundered during the Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
period, the region became part of a shifting transition zone between a shallow inland sea—the Western Interior Seaway
Western Interior Seaway
The Western Interior Seaway, also called the Cretaceous Seaway, the Niobraran Sea, and the North American Inland Sea, was a huge inland sea that split the continent of North America into two halves, Laramidia and Appalachia, during most of the mid- and late-Cretaceous Period...
—and a band of plains and low hills to the west. A sandy and swampy coastline oscillated east and west, alternately submerging and uncovering the area atop the present Colorado Plateau that Chaco Canyon now occupies.
As the Chaco Wash flowed across the upper strata of what is now the 400 feet (121.9 m) Chacra Mesa
Chacra Mesa
The Chacra Mesa is a high mesa massif composing the southwestern flank of Chaco Canyon, a region that is notable for its rich collection of ancient Chacoan Anasazi archaeological sites....
, it cut into it, gouging out a broad canyon over the course of millions of years. The mesa comprises sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
and shale
Shale
Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...
formations dating from the Late Cretaceous
Late Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
, which are of the Mesa Verde formation
Geologic formation
A formation or geological formation is the fundamental unit of lithostratigraphy. A formation consists of a certain number of rock strata that have a comparable lithology, facies or other similar properties...
. The canyon bottomlands were further eroded, exposing Menefee Shale
Menefee Shale
The Menefee Shale is a geological stratum underlying the Chaco Wash, which is located in the northwestern portion of the U.S. state of New Mexico, in what is now Chaco Culture National Historical Park...
bedrock
Bedrock
In stratigraphy, bedrock is the native consolidated rock underlying the surface of a terrestrial planet, usually the Earth. Above the bedrock is usually an area of broken and weathered unconsolidated rock in the basal subsoil...
; this was subsequently buried under roughly 125 feet (38.1 m) of sediment
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
. The canyon and mesa lie within the "Chaco Core", distinct from the wider Chaco Plateau, the latter a flat region of grassland with infrequent stands of timber. As the Continental Divide
Continental Divide
The Continental Divide of the Americas, or merely the Continental Gulf of Division or Great Divide, is the name given to the principal, and largely mountainous, hydrological divide of the Americas that separates the watersheds that drain into the Pacific Ocean from those river systems that drain...
is only 15.5 miles (25 km) east of the canyon, geological characteristics and different patterns of drainage differentiate these two regions both from each other and from the nearby Chaco Slope
Chaco Slope
The Chaco Slope is a geographical region located in the northwestern portion of the U.S. state of New Mexico. It borders the Chaco Core, which contains both Chacra Mesa and Chaco Canyon. The canyon itself is noted for its Chacoan Anasazi ruins...
, the Gobernador Slope
Gobernador Slope
The Gobernador Slope is a geographical region located in the northwestern portion of the U.S. state of New Mexico. It is near both Chacra Mesa and Chaco Canyon, which are noted for their Chacoan Anasazi ruins. The Chaco Slope is differentiated from the neighboring Chuska Valley, Chaco Core and...
, and the Chuska Valley
Chuska Valley
The Chuska Valley is a geographical region located in the northwestern portion of the U.S. state of New Mexico. Sitting atop the Colorado Plateau in the Four Corners region of the desert Southwest, it is near both Chacra Mesa and Chaco Canyon, which are noted for their Chacoan Anasazi ruins...
.
Climate
An arid region of high xeric scrublandDeserts and xeric shrublands
Deserts and xeric shrublands is a biome characterized by, relating to, or requiring only a small amount of moisture.-Definition and occurrence:...
and desert steppe, the canyon and wider basin average 8 inches (203.2 mm) of rainfall annually; the park averages 9.1 inches (231.1 mm). Chaco Canyon lies on the leeward side of extensive mountain ranges to the south and west, resulting in a rainshadow effect that fosters the prevailing lack of moisture in the region. The region sees four distinct seasons. Rainfall is most likely between July and September; May and June are the driest months. Orographic precipitation, which results from moisture wrung out of storm systems ascending the mountain ranges around Chaco Canyon, is responsible for most of the summer and winter precipitation; rainfall increases with higher elevation. Occasional aberrant northward excursions of the intertropical convergence zone
Intertropical Convergence Zone
The Intertropical Convergence Zone , known by sailors as The Doldrums, is the area encircling the earth near the equator where winds originating in the northern and southern hemispheres come together....
may boost precipitation in some years.
Chaco endures remarkable climatic extremes: temperatures range between -38 F, and may swing 60°F (33°C) in one day. The region averages less than 150frost-free days per year, and the local climate swings wildly from years of plentiful rainfall to prolonged drought. The heavy influence of the El Niño-Southern Oscillation
El Niño-Southern Oscillation
El Niño/La Niña-Southern Oscillation, or ENSO, is a quasiperiodic climate pattern that occurs across the tropical Pacific Ocean roughly every five years...
contributes to the canyon's fickle climate.
Flora and fauna
Chacoan flora typifies that of North American high deserts: sagebrushArtemisia tridentata
Artemisia tridentata is a shrub or small tree from the family Asteraceae. Some botanists treat it in the segregate genus Seriphidium, as S. tridentatum W. A. Weber, but this is not widely followed...
and several species of cactus
Cactus
A cactus is a member of the plant family Cactaceae. Their distinctive appearance is a result of adaptations to conserve water in dry and/or hot environments. In most species, the stem has evolved to become photosynthetic and succulent, while the leaves have evolved into spines...
are interspersed with dry scrub forests of piñon
Pinyon pine
The pinyon pine group grows in the southwestern United States and in Mexico. The trees yield edible pinyon nuts, which were a staple of the Native Americans, and are still widely eaten...
and juniper
Juniper
Junipers are coniferous plants in the genus Juniperus of the cypress family Cupressaceae. Depending on taxonomic viewpoint, there are between 50-67 species of juniper, widely distributed throughout the northern hemisphere, from the Arctic, south to tropical Africa in the Old World, and to the...
, the latter primarily on the mesa tops. The canyon is far drier than other parts of New Mexico located at similar latitudes and elevations, and it lacks the temperate coniferous forests
Temperate coniferous forests
Temperate coniferous forest is a terrestrial biome found in temperate regions of the world with warm summers and cool winters and adequate rainfall to sustain a forest. In most temperate coniferous forests, evergreen conifers predominate, while some are a mix of conifers and broadleaf evergreen...
plentiful to the east. The prevailing sparseness of plants and wildlife was echoed in ancient times, when overpopulation, expanding cultivation, overhunting, habitat destruction, and drought may have led the Chacoans to strip the canyon of wild plants and game. It has been suggested that even during wet periods the canyon was able to sustain only 2,000 people.
Among Chacoan mammals are the plentiful coyote
Coyote
The coyote , also known as the American jackal or the prairie wolf, is a species of canine found throughout North and Central America, ranging from Panama in the south, north through Mexico, the United States and Canada...
(Canis latrans); mule deer
Mule Deer
The mule deer is a deer indigenous to western North America. The Mule Deer gets its name from its large mule-like ears. There are believed to be several subspecies, including the black-tailed deer...
, elk
Elk
The Elk is the large deer, also called Cervus canadensis or wapiti, of North America and eastern Asia.Elk may also refer to:Other antlered mammals:...
, and pronghorn
Pronghorn
The pronghorn is a species of artiodactyl mammal endemic to interior western and central North America. Though not an antelope, it is often known colloquially in North America as the prong buck, pronghorn antelope, or simply antelope, as it closely resembles the true antelopes of the Old World and...
also live within the canyon, though they are rarely encountered by visitors. Important smaller carnivores include bobcat
Bobcat
The bobcat is a North American mammal of the cat family Felidae, appearing during the Irvingtonian stage of around 1.8 million years ago . With twelve recognized subspecies, it ranges from southern Canada to northern Mexico, including most of the continental United States...
s, badger
Badger
Badgers are short-legged omnivores in the weasel family, Mustelidae. There are nine species of badger, in three subfamilies : Melinae , Mellivorinae , and Taxideinae...
s, fox
Fox
Fox is a common name for many species of omnivorous mammals belonging to the Canidae family. Foxes are small to medium-sized canids , characterized by possessing a long narrow snout, and a bushy tail .Members of about 37 species are referred to as foxes, of which only 12 species actually belong to...
es, and two species of skunk
Skunk
Skunks are mammals best known for their ability to secrete a liquid with a strong, foul odor. General appearance varies from species to species, from black-and-white to brown or cream colored. Skunks belong to the family Mephitidae and to the order Carnivora...
. The park hosts abundant populations of rodents, including several prairie dog
Prairie dog
Prairie dogs are burrowing rodents native to the grasslands of North America. There are five different species of prairie dogs: black-tailed, white-tailed, Gunnison's, Utah and Mexican prairie dogs. They are a type of ground squirrel, found in the United States, Canada and Mexico...
towns. Small colonies of bat
Bat
Bats are mammals of the order Chiroptera "hand" and pteron "wing") whose forelimbs form webbed wings, making them the only mammals naturally capable of true and sustained flight. By contrast, other mammals said to fly, such as flying squirrels, gliding possums, and colugos, glide rather than fly,...
s, are present during the summer. The local shortage of water means that relatively few bird species are present; these include roadrunners
Geococcyx
The roadrunners are two species of bird in the genus Geococcyx of the cuckoo family, Cuculidae, native to North and Central America...
, large hawk
Hawk
The term hawk can be used in several ways:* In strict usage in Australia and Africa, to mean any of the species in the subfamily Accipitrinae, which comprises the genera Accipiter, Micronisus, Melierax, Urotriorchis and Megatriorchis. The large and widespread Accipiter genus includes goshawks,...
s (such as Cooper's hawk
Cooper's Hawk
Cooper's Hawk is a medium-sized hawk native to the North American continent and found from Canada to Mexico. As in many birds of prey, the male is smaller than the female...
s and American kestrel
American Kestrel
The American Kestrel , sometimes colloquially known as the Sparrow Hawk, is a small falcon, and the only kestrel found in the Americas. It is the most common falcon in North America, and is found in a wide variety of habitats. At long, it is also the smallest falcon in North America...
s), owl
Owl
Owls are a group of birds that belong to the order Strigiformes, constituting 200 bird of prey species. Most are solitary and nocturnal, with some exceptions . Owls hunt mostly small mammals, insects, and other birds, although a few species specialize in hunting fish...
s, vulture
Vulture
Vulture is the name given to two groups of convergently evolved scavenging birds, the New World Vultures including the well-known Californian and Andean Condors, and the Old World Vultures including the birds which are seen scavenging on carcasses of dead animals on African plains...
s, and raven
Raven
Raven is the common name given to several larger-bodied members of the genus Corvus—but in Europe and North America the Common Raven is normally implied...
s, though they are less abundant in the canyon than in the wetter mountain ranges to the east. Sizeable populations of smaller birds, including warblers
New World warbler
The New World warblers or wood-warblers are a group of small, often colorful, passerine birds restricted to the New World. They are not related to the Old World warblers or the Australian warblers....
, sparrow
Sparrow
The sparrows are a family of small passerine birds, Passeridae. They are also known as true sparrows, or Old World sparrows, names also used for a genus of the family, Passer...
s, and house finches
House Finch
The House Finch is a bird in the finch family Fringillidae, which is found in North America. This species and the other "American rosefinches" are usually placed in the rosefinch genus Carpodacus...
, are also common. Three species of hummingbird
Hummingbird
Hummingbirds are birds that comprise the family Trochilidae. They are among the smallest of birds, most species measuring in the 7.5–13 cm range. Indeed, the smallest extant bird species is a hummingbird, the 5-cm Bee Hummingbird. They can hover in mid-air by rapidly flapping their wings...
s are present: one is the tiny but highly pugnacious rufous hummingbird
Rufous Hummingbird
The Rufous Hummingbird is a small hummingbird, about 8 cm long with a long, straight and very slender bill. The female is slightly larger than the male.-Description:...
, which compete intensely with the more mild-tempered black-chinned hummingbird
Black-chinned Hummingbird
The Black-chinned Hummingbird is a small hummingbird.Adults are metallic green above and white below with green flanks. Their bill is long, straight and very slender. The adult male has a black face and chin, a glossy purple throat band and a dark forked tail...
s for breeding habitat in shrubs or trees located near water. Western (prairie) rattlesnakes
Crotalus oreganus
Crotalus oreganus is a venomous pitviper species found in North America in the western United States, parts of British Columbia and northwestern Mexico. Seven subspecies are currently recognized, including the nominate subspecies described here....
are occasionally seen in the backcountry, though various lizards and skink
Skink
Skinks are lizards belonging to the family Scincidae. Together with several other lizard families, including Lacertidae , they comprise the superfamily or infraorder Scincomorpha...
s are far more abundant.
Archaic–Early Basketmakers
The first people in the San Juan BasinSan Juan Basin
The San Juan Basin is a geologic structural basin in the Four Corners region of the Southwestern United States; its main portion covers around , encompassing much of northwestern New Mexico, southwest Colorado, and parts of Arizona and Utah....
were hunter-gatherers: the Archaic–Early Basketmaker
Archaic–Early Basketmaker Era
The Archaic–Early Basketmaker Era, 7000 - 1500 BC was an Archaic cultural period of ancestors to the Ancient Pueblo People. They were distinguished from other Archaic people of the Southwest by their basketry which was used to gather and store food...
people. These small bands descended from nomadic Clovis
Clovis culture
The Clovis culture is a prehistoric Paleo-Indian culture that first appears 11,500 RCYBP , at the end of the last glacial period, characterized by the manufacture of "Clovis points" and distinctive bone and ivory tools...
big-game hunters who arrived in the Southwest around 10,000 BC. More than 70 campsites from this period, carbon-dated to the period 7000–1500 BC and mostly consisting of stone chips and other leavings, were found in Atlatl Cave and elsewhere within Chaco Canyon, with at least one of the sites located on the canyon floor near an exposed arroyo. The Archaic–Early Basketmaker people were nomadic or semi-nomadic hunter-gatherer
Hunter-gatherer
A hunter-gatherer or forage society is one in which most or all food is obtained from wild plants and animals, in contrast to agricultural societies which rely mainly on domesticated species. Hunting and gathering was the ancestral subsistence mode of Homo, and all modern humans were...
s who over time began making baskets to store gathered plants. By the end of the period, some people cultivated food. Excavation of their campsites and rock shelters has revealed that they made tools, gathered wild plants, and killed and processed game. Slab-lined storage cisterns indicate a change from a wholly nomadic lifestyle.
Ancestral Puebloans
Late Basketmaker II Era
The Late Basketmaker II Era was a cultural period of Ancient Pueblo People when people began living in pit-houses, raised maize and squash, and were proficient basket makers and weavers...
, farmed lands around Shabik'eshchee Village and other pit-house
Pit-house
A pit-house is a dwelling dug into the ground which may also be layered with stone.These structures may be used as places to tell stories, dance, sing, celebrate, and store food. In archaeology, pit-houses are also termed sunken featured buildings and are found in numerous cultures around the world...
settlements at Chaco.
A small population of Basketmaker
Basketmaker (culture)
The Basketmaker culture of the Ancient Pueblo People began about 1500 BC and continued until about AD 500 with the beginning of the Pueblo I Era...
s remained in the Chaco Canyon area. The broad arc of their cultural elaboration culminated around 800, during the Pueblo I Era
Pueblo I Era
The Pueblo I Era, from AD 750 to 900, was the first period in which Ancient Pueblo People began living in pueblo structures and realized an evolution in architecture, artistic expression, and water conservation...
, when they were building crescent-shaped stone complexes, each comprising four to five residential suites abutting subterranean kiva
Kiva
A kiva is a room used by modern Puebloans for religious rituals, many of them associated with the kachina belief system. Among the modern Hopi and most other Pueblo peoples, kivas are square-walled and underground, and are used for spiritual ceremonies....
s, large enclosed areas reserved for rites. Such structures characterize the Early Pueblo People
Pecos Classification
The Pecos Classification is a division of all known Ancient Pueblo Peoples culture into chronological phases, based on changes in architecture, art, pottery, and cultural remains. The original classification dates back to consensus reached at a 1927 archæological conference held in Pecos, New...
. By 850, the Ancient Pueblo population—the "Anasazi", from a Ute
Ute Tribe
The Ute are an American Indian people now living primarily in Utah and Colorado. There are three Ute tribal reservations: Uintah-Ouray in northeastern Utah ; Southern Ute in Colorado ; and Ute Mountain which primarily lies in Colorado, but extends to Utah and New Mexico . The name of the state of...
term adopted by the Navajo
Navajo language
Navajo or Navaho is an Athabaskan language spoken in the southwestern United States. It is geographically and linguistically one of the Southern Athabaskan languages .Navajo has more speakers than any other Native American language north of the...
denoting the "ancient ones" or "enemy ancestors"—had rapidly expanded: groups resided in larger, denser pueblos. Strong evidence attests to a canyon-wide turquoise processing and trading industry dating from the 10th century. Around then, the first section of Pueblo Bonito
Pueblo Bonito
Pueblo Bonito, the largest and best known Great House in Chaco Culture National Historical Park, northern New Mexico, was built by ancestral Pueblo people and occupied between AD 828 and 1126....
was built: a curved row of 50 rooms near its present north wall.
The cohesive Chacoan system began unravelling around 1140, perhaps triggered by an extreme fifty-year drought that began in 1130; chronic climatic instability, including a series of severe droughts, again struck the region between 1250 and 1450. Poor water management lead to arroyo cutting; deforestation was extensive and economically devastating: timber for construction had to instead be hauled from outlying mountain ranges such as the Chuska Mountains
Chuska mountains
The Chuska Mountains are an elongate range on the Colorado Plateau and within the Navajo Nation. The range is about 80 by 15 km , and it trends north-northwest and is crossed by the state line between Arizona and New Mexico. The highlands are a dissected plateau, with an average elevation of...
, which are over 50 miles (80.5 km) to the west. Outlying communities began to depopulate and, by the end of the century, the buildings in the central canyon had been neatly sealed and abandoned.
Some scholars suggest that violence and warfare, perhaps involving cannibalism, impelled the evacuations. Hints of such include dismembered bodies—dating from Chacoan times—found at two sites within the central canyon. Yet Chacoan complexes showed little evidence of being defended or defensively sited high on cliff faces or atop mesas, and only several minor sites at Chaco evidence the large-scale burning that would suggest enemy raids. Archaeological and cultural evidence leads scientists to believe people from this region migrated south, east, and west into the valleys and drainages of the Little Colorado River
Little Colorado River
The Little Colorado River is a river in the U.S. state of Arizona, providing the principal drainage from the Painted Desert region. Together with its major tributary, the Puerco River, it drains an area of about in eastern Arizona and western New Mexico...
, the Rio Puerco, and the Rio Grande
Rio Grande
The Rio Grande is a river that flows from southwestern Colorado in the United States to the Gulf of Mexico. Along the way it forms part of the Mexico – United States border. Its length varies as its course changes...
. Anthropologist Joseph Tainter
Joseph Tainter
Joseph A. Tainter is a U.S. anthropologist and historian.Tainter studied anthropology at the University of California and Northwestern University, where he received his Ph.D. in 1975. He is currently a professor in the Department of Environment and Society at Utah State University...
deals at length with the structure and decline of Chaco civilization in his 1988 study The Collapse of Complex Societies.
Athabaskan succession
Numic-speaking peoples, such as the UteUte Tribe
The Ute are an American Indian people now living primarily in Utah and Colorado. There are three Ute tribal reservations: Uintah-Ouray in northeastern Utah ; Southern Ute in Colorado ; and Ute Mountain which primarily lies in Colorado, but extends to Utah and New Mexico . The name of the state of...
and Shoshone
Shoshone
The Shoshone or Shoshoni are a Native American tribe in the United States with three large divisions: the Northern, the Western and the Eastern....
, were present on the Colorado Plateau beginning in the 12th century. Nomadic Southern Athabaskan speaking peoples, such as the Apache
Apache
Apache is the collective term for several culturally related groups of Native Americans in the United States originally from the Southwest United States. These indigenous peoples of North America speak a Southern Athabaskan language, which is related linguistically to the languages of Athabaskan...
and Navajo
Navajo people
The Navajo of the Southwestern United States are the largest single federally recognized tribe of the United States of America. The Navajo Nation has 300,048 enrolled tribal members. The Navajo Nation constitutes an independent governmental body which manages the Navajo Indian reservation in the...
, succeeded the Pueblo people in this region by the 15th century; in the process, they acquired Chacoan customs and agricultural skills. Ute tribal groups also frequented the region, primarily during hunting and raiding expeditions. The modern Navajo Nation lies west of Chaco Canyon, and many Navajo live in surrounding areas. The arrival of the Spanish in the 17th century inaugurated an era of subjugation and rebellion, with the Chaco Canyon area absorbing Puebloan and Navajo refugees fleeing Spanish rule. In succession, as first Mexico, then the U.S., gained sovereignty over the canyon, military campaigns were launched against the region's remaining inhabitants.
Excavation and protection
The trader Josiah GreggJosiah Gregg
Josiah Gregg was a merchant, explorer, naturalist, and author of the American Southwest and Northern Mexico regions. He is most famous for his book Commerce of the Prairies.-Early years:...
was the first to write about the ruins of Chaco Canyon, referring in 1832 to Pueblo Bonito as "built of fine-grit sandstone". In 1849, a U.S. Army detachment passed through and surveyed the ruins. The canyon was so remote, however, that it was scarcely visited over the next 50 years. After brief reconnaissance work by Smithsonian scholars in the 1870s, formal archaeological work began in 1896 when a party from the American Museum of Natural History
American Museum of Natural History
The American Museum of Natural History , located on the Upper West Side of Manhattan in New York City, United States, is one of the largest and most celebrated museums in the world...
—the "Hyde Exploring Expedition"—began excavating Pueblo Bonito. Spending five summers in the region, they sent over 60,000 artifacts back to New York and operated a series of trading posts.
In 1901 Richard Wetherill
Richard Wetherill
Richard Wetherill , a member of a prominent Colorado ranching family, was an amateur explorer in the discovery, research and excavation of sites associated with the Ancient Pueblo People...
, who had worked for the Hyde expedition, claimed a homestead
Homestead Act
A homestead act is one of three United States federal laws that gave an applicant freehold title to an area called a "homestead" – typically 160 acres of undeveloped federal land west of the Mississippi River....
of 161 acres (65.2 ha) that included Pueblo Bonito, Pueblo del Arroyo
Pueblo del Arroyo
Pueblo del Arroyo is a Chacoan Anasazi great house and notable archaeological site located in Chaco Canyon, a canyon in the U.S. state of New Mexico. Founded between 1050 and 1075 AD and completed in the early 12th century, it is located near Pueblo Bonito at a drainage outlet known as South Gap....
, and Chetro Ketl
Chetro Ketl
Chetro Ketl is a Chacoan Anasazi great house and notable archaeological site located in Chaco Canyon, a canyon in the U.S. state of New Mexico. In the cliffs behind the ruins there are ancient stairways that lead to prehistoric roadways that connect to Pueblo Bonito...
. While investigating Wetherill's land claim, federal land agent Samuel J. Holsinger detailed the physical setting of the canyon and the sites, noted prehistoric road segments and stairways above Chetro Ketl, and documented prehistoric dams and irrigation systems. His report went unpublished and unheeded. It urged the creation of a national park to safeguard Chacoan sites. The next year, Edgar Lee Hewett
Edgar Lee Hewett
Edgar Lee Hewett, D.Sc., was an archaeologist/anthropologist active in work on the Native American communities of New Mexico and the southwestern United States, and most famous for his role in bringing about the Antiquities Act, a pioneering piece of legislation for the conservation movement...
, president of New Mexico Normal University (later renamed New Mexico Highlands University
New Mexico Highlands University
New Mexico Highlands University is a public university located in Las Vegas, New Mexico.-History:The university was first established as New Mexico Normal School in 1893, with the prominent archaeologist Edgar Lee Hewett serving as its first president...
), mapped many Chacoan sites. Hewett and others helped enact the Federal Antiquities Act of 1906
Antiquities Act
The Antiquities Act of 1906, officially An Act for the Preservation of American Antiquities , is an act passed by the United States Congress and signed into law by Theodore Roosevelt on June 8, 1906, giving the President of the United States authority to, by executive order, restrict the use of...
, the first U.S. law to protect relics; it was, in effect, a direct consequence of Wetherill's controversial activities at Chaco. The Act also authorized the President to found national monuments
U.S. National Monument
A National Monument in the United States is a protected area that is similar to a National Park except that the President of the United States can quickly declare an area of the United States to be a National Monument without the approval of Congress. National monuments receive less funding and...
: on March 11, 1907, Theodore Roosevelt proclaimed Chaco Canyon National Monument. Wetherill relinquished his claims.
In 1920, the National Geographic Society
National Geographic Society
The National Geographic Society , headquartered in Washington, D.C. in the United States, is one of the largest non-profit scientific and educational institutions in the world. Its interests include geography, archaeology and natural science, the promotion of environmental and historical...
began an archaeological examination of Chaco Canyon, and appointed Neil Judd
Neil Judd
Neil Merton Judd was an American archaeologist who studied under the pioneering archaeologist of the American Southwest, Edgar Lee Hewett. He was curator of archaeology at the erstwhile United States National Museum, which later became part of the Smithsonian Institution...
, then 32, to head the project. After a reconnaissance trip that year, Judd proposed to excavate Pueblo Bonito
Pueblo Bonito
Pueblo Bonito, the largest and best known Great House in Chaco Culture National Historical Park, northern New Mexico, was built by ancestral Pueblo people and occupied between AD 828 and 1126....
, the largest ruin at Chaco. Beginning in 1921, Judd spent seven field seasons at Chaco. Living and working conditions were spartan at best. In his memoirs, Judd noted dryly that "Chaco Canyon has its limitations as a summer resort". By 1925, Judd's excavators had removed 100,000 short tons of overburden
Overburden
Overburden is the material that lies above an area of economic or scientific interest in mining and archaeology; most commonly the rock, soil, and ecosystem that lies above a coal seam or ore body. It is also known as 'waste' or 'spoil'...
, using a team of "35 or more Indians, ten white men, and eight or nine horses". One puzzling discovery was that Judd's team only found 69 hearths in the ruin; winters are cold at Chaco. Judd sent A. E. Douglass
A. E. Douglass
A. E. Douglass was an American astronomer. He discovered a correlation between tree rings and the sunspot cycle....
more than 90 specimens for tree-ring dating, then in its infancy. At that time, Douglass had only a "floating" chronology. it was not until 1929 that a Judd-led team found the "missing link". Most of the beams used at Chaco were cut between 1033 and 1092, the height of construction there.
In 1949, the University of New Mexico
University of New Mexico
The University of New Mexico at Albuquerque is a public research university located in Albuquerque, New Mexico, in the United States. It is the state's flagship research institution...
deeded over adjoining lands to form an expanded Chaco Canyon National Monument. In return, the university maintained scientific research rights to the area. By 1959, the National Park Service
National Park Service
The National Park Service is the U.S. federal agency that manages all national parks, many national monuments, and other conservation and historical properties with various title designations...
had constructed a park visitor center, staff housing, and campgrounds. As a historic property of the National Park Service, the National Monument was listed on the National Register of Historic Places
National Register of Historic Places
The National Register of Historic Places is the United States government's official list of districts, sites, buildings, structures, and objects deemed worthy of preservation...
on October 15, 1966. In 1971, researchers Robert Lister and James Judge established the "Chaco Center", a division for cultural research that functioned as a joint project between the University of New Mexico and the National Park Service. A number of multi-disciplinary research projects, archaeological surveys, and limited excavations began during this time. The Chaco Center extensively surveyed the Chacoan roads, well-constructed and heavily built thoroughfares radiating from the central canyon. The results from such research conducted at Pueblo Alto and other sites dramatically altered accepted academic interpretations of both the Chacoan culture and the Four Corners region of the American Southwest.
The richness of the cultural remains at park sites led to the expansion of the small National Monument into the Chaco Culture National Historical Park on December 19, 1980, when an additional 13000 acres (5,260.9 ha) were added to the protected area. In 1987, the park was designated a World Heritage Site
World Heritage Site
A UNESCO World Heritage Site is a place that is listed by the UNESCO as of special cultural or physical significance...
by UNESCO
UNESCO
The United Nations Educational, Scientific and Cultural Organization is a specialized agency of the United Nations...
. To safeguard Chacoan sites on adjacent Bureau of Land Management
Bureau of Land Management
The Bureau of Land Management is an agency within the United States Department of the Interior which administers America's public lands, totaling approximately , or one-eighth of the landmass of the country. The BLM also manages of subsurface mineral estate underlying federal, state and private...
and Navajo Nation
Navajo Nation
The Navajo Nation is a semi-autonomous Native American-governed territory covering , occupying all of northeastern Arizona, the southeastern portion of Utah, and northwestern New Mexico...
lands, the Park Service developed the multi-agency Chaco Culture Archaeological Protection Site program. These initiatives have detailed the presence of more than 2,400 archeological sites within the current park's boundaries; only a small percentage of these have been excavated.
Management
Chaco Culture National Historical Park is managed by the National Park ServiceNational Park Service
The National Park Service is the U.S. federal agency that manages all national parks, many national monuments, and other conservation and historical properties with various title designations...
, a federal agency within the Department of the Interior; neighboring federal lands hosting Chacoan roads are controlled by the Bureau of Land Management
Bureau of Land Management
The Bureau of Land Management is an agency within the United States Department of the Interior which administers America's public lands, totaling approximately , or one-eighth of the landmass of the country. The BLM also manages of subsurface mineral estate underlying federal, state and private...
. In the 2002–2003 fiscal year, the park's total annual operating budget was 1,434,000. The park has a visitor center, which features the "Chaco Collection Museum", an information desk, a theater, a book store, and a gift shop. Prior to the 1980s, archeological excavations within current park boundaries were intensive: compound walls were dismantled or demolished, and thousands of artifacts were extracted. Starting in 1981, a new approach, informed by traditional Hopi and Pueblo beliefs, stopped such intrusions. Remote sensing
Remote sensing
Remote sensing is the acquisition of information about an object or phenomenon, without making physical contact with the object. In modern usage, the term generally refers to the use of aerial sensor technologies to detect and classify objects on Earth by means of propagated signals Remote sensing...
, anthropological study of Indian oral traditions, and dendrochronology—which left Chacoan relics undisturbed—were touted. In this vein, the "Chaco American Indian Consultation Committee" was established in 1991 to give Navajo, Hopi, Pueblo, and other Indian representatives a voice in park oversight.
Current park policy mandates partial restoration of excavated sites. "Backfilling", or re-burying excavated sites with sand, is one such means. Other measures attempt to safeguard the area's ancient ambiance and mystique: the "Chaco Night Sky Program", which seeks to eliminate the impact of light pollution
Light pollution
Light pollution, also known as photopollution or luminous pollution, is excessive or obtrusive artificial light.The International Dark-Sky Association defines light pollution as:...
on the park's acclaimed night skies; under the program, some 14,000 visitors make use of the Chaco Observatory (inaugurated in 1998), park telescopes, and astronomy-related programs. Chacoan relics outside the current park's boundaries have been threatened by development: an example was the proposed competitive leasing of federal lands in the San Juan Basin for surface coal mining beginning in 1983. As ample coal deposits abut the park, this strip mining threatened the web of ancient Chacoan roads. The year-long "Chaco Roads Project" thus documented the roads, which were later protected from mining.
Sites
The Chacoans built their complexes along a 9 mi (14 km) stretch of canyon floor, with the walls of some structures aligned cardinally and others aligned with the 18.6-year cycle of minimum and maximum moonrise and moonset. Nine Great Houses are positioned along the north side of Chaco Wash, at the base of massive sandstone mesas. Other Great Houses are found on mesa tops or in nearby washes and drainage areas. There are fourteen recognized Great Houses, which are grouped below according to geographic positioning with respect to the canyon.Central canyon
The central portion of the canyon contains the largest Chacoan complexes. The most studied is Pueblo BonitoPueblo Bonito
Pueblo Bonito, the largest and best known Great House in Chaco Culture National Historical Park, northern New Mexico, was built by ancestral Pueblo people and occupied between AD 828 and 1126....
; covering almost 2 acre (0.809372 ha) and comprising at least 650 rooms, it is the largest Great House; in parts of the complex, the structure was four stories high. The builders' use of core-and-veneer architecture and multi-story construction necessitated massive masonry walls up to 3 feet (91.4 cm) thick. Pueblo Bonito is divided into two sections by a wall precisely aligned to run north-south, bisecting the central plaza. A Great Kiva was placed on either side of the wall, creating a symmetrical pattern common to many Chacoan Great Houses. The scale of the complex, upon completion, rivaled that of the Colosseum.
Nearby is Pueblo del Arroyo
Pueblo del Arroyo
Pueblo del Arroyo is a Chacoan Anasazi great house and notable archaeological site located in Chaco Canyon, a canyon in the U.S. state of New Mexico. Founded between 1050 and 1075 AD and completed in the early 12th century, it is located near Pueblo Bonito at a drainage outlet known as South Gap....
. Founded between AD 1050 and 1075, completed in the early 12th century, it sits at a drainage outlet known as South Gap. Casa Rinconada, isolated from the other central sites, sits to the south side of Chaco Wash, adjacent to a Chacoan road leading to a set of steep stairs that reached the top of Chacra Mesa. Its sole kiva stands alone, with no residential or support structures whatever; it did once had a 39 feet (11.9 m) passageway leading from the underground kiva to several above-ground levels. Chetro Ketl
Chetro Ketl
Chetro Ketl is a Chacoan Anasazi great house and notable archaeological site located in Chaco Canyon, a canyon in the U.S. state of New Mexico. In the cliffs behind the ruins there are ancient stairways that lead to prehistoric roadways that connect to Pueblo Bonito...
, located near Pueblo Bonito, bears the typical 'D'-shape of many other central complexes, but is slightly smaller. Begun between AD 1020 and 1050, its 450–550 rooms shared one Great Kiva. Experts estimate that it took 29,135man-hours to erect Chetro Ketl alone; Hewett estimated that it took the wood of 5,000 trees and 50 million stone blocks.
Kin Kletso
Kin Kletso
Kin Kletso is a Chacoan Anasazi great house and notable archaeological site located in Chaco Culture National Historical Park, located 25 miles southwest of Nageezi, New Mexico, U.S....
("Yellow House") was a medium-sized complex located 0.5 miles (804.7 m) west of Pueblo Bonito. It shows strong evidence of construction and occupation by Pueblo peoples from the northern San Juan Basin. Its rectangular shape and design is related to the Pueblo II
Pueblo II Era
The Pueblo II Era, AD 900 to 1150, was the second pueblo period of the Ancient Pueblo People of the Four Corners region of the American southwest. During this period people lived in dwellings made of stone and mortar, enjoyed communal activities in kivas, built towers and water conversing dams,...
cultural group, rather than the Pueblo III style or its Chacoan variant. It contains 55 rooms, four ground-floor kivas, and a two-story cylindrical tower that may have functioned as a kiva or religious center. Evidence of an obsidian
Obsidian
Obsidian is a naturally occurring volcanic glass formed as an extrusive igneous rock.It is produced when felsic lava extruded from a volcano cools rapidly with minimum crystal growth...
-processing industry was discovered near the village, which was erected between AD 1125 and 1130.
Pueblo Alto
Pueblo Alto is a Chacoan Anasazi great house and archaeological site located in Chaco Canyon, northwestern New Mexico, United States. The complex, comprising 89 rooms in a single-story layout, is located on a mesa top near the middle of Chaco Canyon; 0.6 miles from Pueblo Bonito, it was...
is a Great House of 89 rooms located on a mesa top near the middle of Chaco Canyon, and is 0.6 mile (0.965604 km) from Pueblo Bonito; it was begun between AD 1020 and 1050 during a wider building boom throughout the canyon. Its location made the community visible to most of the inhabitants of the San Juan Basin; indeed, it was only 2.3 miles (3.7 km) north of Tsin Kletsin, on the opposite side of the canyon. The community was the center of a bead- and turquoise
Turquoise
Turquoise is an opaque, blue-to-green mineral that is a hydrous phosphate of copper and aluminium, with the chemical formula CuAl648·4. It is rare and valuable in finer grades and has been prized as a gem and ornamental stone for thousands of years owing to its unique hue...
-processing industry that influenced the development of all villages in the canyon; chert
Chert
Chert is a fine-grained silica-rich microcrystalline, cryptocrystalline or microfibrous sedimentary rock that may contain small fossils. It varies greatly in color , but most often manifests as gray, brown, grayish brown and light green to rusty red; its color is an expression of trace elements...
tool production was common. Research at the site conducted by archaeologist Tom Windes suggests only a handful of families, perhaps as few as five to twenty, lived in the complex; this may imply that Pueblo Alto served a primarily non-residential role. Another Great House, Nuevo Alto
Nuevo Alto
Nuevo Alto is a Chacoan Anasazi great house and notable archaeological site located in Chaco Canyon, a canyon in the U.S. state of New Mexico. It was built on the north mesa near Pueblo Alto, and was founded in the late 12th century, a time when the Chacoan population was declining in the canyon;...
, was built on the north mesa near Pueblo Alto; it was founded in the late 12th century, a time when the Chacoan population was declining.
Outliers
In Chaco's northern reaches lies another cluster of Great Houses; among the largest are Casa ChiquitaCasa Chiquita
Casa Chiquita is a Chacoan Anasazi great house and archaeological site located in Chaco Canyon, northwestern New Mexico, United States. Located near the old north entrance to the Canyon, its layout features a smaller profile with a square block of rooms surrounding a central elevated round room....
("Small House"), a village built in the AD 1080s, when, in a period of ample rainfall, Chacoan culture was expanding. Its layout featured a smaller, squarer profile; it also lacked the open plazas and separate kivas of its predecessors. Larger, squarer blocks of stone were used in the masonry; kivas were designed in the northern Mesa Verdean tradition. Two miles down the canyon is Peñasco Blanco
Peñasco Blanco
Peñasco Blanco is a Chacoan Anasazi great house and notable archaeological site located in Chaco Canyon, a canyon in San Juan County, New Mexico, United States.. It is an arc-shaped compound built atop the canyon's southern rim; it was constructed in five distinct stages between 900 AD and 1125 AD...
("White Bluff"), an arc-shaped compound built atop the canyon's southern rim in five distinct stages between AD 900 and 1125. A cliff painting (the "Supernova Platograph") nearby may record the sighting of the SN 1054
SN 1054
SN 1054 is a supernova that was first observed as a new "star" in the sky on July 4, 1054 AD, hence its name, and that lasted for a period of around two years. The event was recorded in multiple Chinese and Japanese documents and in one document from the Arab world...
supernova on July 5, 1054.
Hungo Pavi
Hungo Pavi
Hungo Pavi is a Chacoan Anasazi great house and archaeological site located in Chaco Canyon, northwestern New Mexico, United States. A set of ruins located just 1 mile from the ruins of Una Vida, Hungo Pavi measured 872 feet in circumference. Initial explorations revealed 72...
, located 1 mi (1.6 km) from Una Vida, measured 872 feet (265.8 m) in circumference. Initial probes revealed 72 ground-level rooms, with structures reaching four stories in height; one large circular kiva has been identified. Kin Nahasbas
Kin Nahasbas
Kin Nahasbas is a Chacoan Anasazi great house and archaeological site located in Chaco Canyon, 25 miles southwest of Nageezi, New Mexico, United States. Built in either the 9th or 10th centuries, it was major pueblo located slightly north of the Una Vida complex, which is positioned at the foot of...
, built in either the 9th or 10th century, is sited slightly north of Una Vida, positioned at the foot of the north mesa. Limited excavation of it has taken place. Tsin Kletzin
Tsin Kletzin
Tsin Kletzin or Tsin Kletsin is a Chacoan Anasazi archaeological site located on top of South Mesa in Chaco Culture National Historical Park, northwestern New Mexico, United States. It is located 3.2 kilometers south of Pueblo Bonito. Tree-ring dating placed the construction around 1110-1115 A.D...
("Charcoal Place"), a compound located on the Chacra Mesa and positioned above Casa Rinconada
Casa Rinconada
Casa Rinconada is a Chacoan Anasazi archaeological site located atop a ridge adjacent to a small rincon across from Pueblo Bonito in Chaco Culture National Historical Park, northwestern New Mexico, United States....
, is 2.3 miles (3.7 km) due south of Pueblo Alto, on the opposite side of the canyon. Nearby is Weritos Dam, a massive earthen structure that scientists believe provided Tsin Kletzin with all of its domestic water. The dam worked by retaining stormwater runoff in a reservoir. Massive amounts of silt accumulated during flash floods would have forced the residents to regularly rebuild the dam and dredge the catchment area.
Deeper in the canyon, Una Vida
Una Vida
Una Vida is an archaeological site located in Chaco Canyon, San Juan County, New Mexico, United States. Its construction began around 900 AD and it is one of the three earliest Chacoan Anasazi great houses; it...
("One Life") is one of the three oldest Great Houses; construction began around AD 900. Comprising at least two stories and 124 rooms, it shares an arc or "D"-shaped design with its contemporaries, Peñasco Blanco and Pueblo Bonito, but has a unique "dog leg" addition made necessary by topography. It is located in one of the canyon's major side drainages, near Gallo Wash, and was massively expanded after 930. Wijiji
Wijiji
Wijiji is a Chacoan Anasazi great house and notable archaeological site located in Chaco Canyon, a canyon in the U.S. state of New Mexico. Comprising just over 100 rooms, it is the smallest of the Chacoan great houses. Built between 1110 AD and 1115 AD, it was the last Chacoan great house to be...
("Greasewood
Greasewood
Greasewood, Sarcobatus, is a genus of one or two species of flowering plants. Traditionally it has been treated in the family Chenopodiaceae, but the APG II system, of 2003, places it in the family Sarcobataceae....
"), comprising just over one hundred rooms, is the smallest of the Great Houses. Built between AD 1110 and 1115, it was the last Chacoan Great House to be constructed. Somewhat isolated within the narrow wash, it is positioned 1 mi (1.6 km) from neighboring Una Vida. Directly north are communities even more remote: Salmon Ruins
Salmon Ruins
Salmon Ruins is a site in the far northwest of the American state of New Mexico hosting a Chacoan Anasazi great house built between approximately 1088 CE and 1100 CE. The complex contained around 150 ground-level rooms arranged into a D-shaped profile; up to 100 second-floor rooms are estimated to...
and Aztec Ruins, sited on the San Juan and Animas River
Animas River
Animas River is a river in the western United States, a tributary of the San Juan River, part of the Colorado River System. The Spanish named the river "Rio de las Animas Perdidas", "River of the Lost Souls". It is also the last free-flowing river in Colorado. The river's free-flowing status...
s near Farmington, were built during a thirty-year wet period commencing in AD 1100. Some 60 mi (97 km) directly south of Chaco Canyon, on the Great South Road, lies another cluster of outlying communities. The largest, Kin Nizhoni, stands atop a 7000 feet (2,133.6 m) mesa surrounded by marshy bottomlands.
"Great Houses"
Immense complexes known as "Great Houses" embodied worship at Chaco. The Chacoans used masonry techniques unique for their time, and their building constructions lasted decades and even centuries. As architectural forms evolved and centuries passed, the houses kept several core traits. Most apparent is their sheer bulk; complexes averaged more than 200 rooms each, and some enclosed up to 700 rooms. Individual rooms were substantial in size, with higher ceilings than Anasazi works of preceding periods. They were well-planned: vast sections or wings erected were finished in a single stage, rather than in increments. Houses generally faced the south, and plaza areas were almost always girt with edifices of sealed-off rooms or high walls. Houses often stood four or five stories tall, with single-story rooms facing the plaza; room blocks were terraced to allow the tallest sections to compose the pueblo's rear edifice. Rooms were often organized into suites, with front rooms larger than rear, interior, and storage rooms or areas.Ceremonial structures known as kiva
Kiva
A kiva is a room used by modern Puebloans for religious rituals, many of them associated with the kachina belief system. Among the modern Hopi and most other Pueblo peoples, kivas are square-walled and underground, and are used for spiritual ceremonies....
s were built in proportion to the number of rooms in a pueblo. One small kiva was built for roughly every 29 rooms. Nine complexes each hosted an oversized Great Kiva, each up to 63 feet (19.2 m) in diameter. "T"-shaped doorways and stone lintels marked all Chacoan kivas. Though simple and compound walls were often used, Great Houses were primarily constructed of core-and-veneer walls: two parallel load-bearing walls comprising dressed, flat sandstone blocks bound in clay mortar were erected. Gaps between walls were packed with rubble, forming the wall's core. Walls were then covered in a veneer of small sandstone pieces, which were pressed into a layer of binding mud. These surfacing stones were often placed in distinctive patterns. The Chacoan structures altogether required the wood of 200,000 coniferous trees, mostly hauled—on foot—from mountain ranges up to 70 miles (112.7 km) away.
Uses
The meticulously designed buildings composing the larger Chacoan complexes did not emerge until around AD 1030. The Chacoans melded pre-planned architectural designs, astronomical alignments, geometry, landscaping, and engineering into ancient urban centers of unique public architecture. Researchers have concluded that the complex may have had a relatively small residential population, with larger groups assembling only temporarily for annual ceremonies. Smaller sites, apparently more residential in character, are scattered near the Great Houses in and around Chaco. The canyon itself runs along one of the lunar alignment lines, suggesting the location was originally chosen for its astronomical significance. If nothing else, this allowed alignment with several other key structures in the canyon.
Around this time, the extended Ancestral Puebloan (Anasazi) community experienced a population and construction boom. Throughout the 10th century, Chacoan building techniques spread from the canyon to neighboring regions. By AD 1115 at least 70 outlying pueblos of Chacoan provenance had been built within the 25000 square miles (64,749.7 km²) composing the San Juan Basin. Experts speculate the function of these compounds, some large enough to be considered Great Houses in their own right. Some suggest they may have been more than agricultural communities, perhaps functioning as trading posts or ceremonial sites.
Thirty such outliers spread across 65000 square miles (168,349.2 km²) are connected to the central canyon and to one another by an enigmatic web of six Chacoan road systems. Extending up to 60 miles (96.6 km) in generally straight routes, they appear to have been extensively surveyed and engineered. Their depressed and scraped caliche
Caliche (Mineral)
Caliche is a sedimentary rock, a hardened deposit of calcium carbonate. This calcium carbonate cements together other materials, including gravel, sand, clay, and silt. It is found in aridisol and mollisol soil orders...
beds reach 30 feet (9.1 m) wide; earthen berms or rocks, at times composing low walls, delimit their edges. When necessary, the roads deploy steep stone stairways and rock ramps to surmount cliffs and other obstacles. Though their purpose may never be certain, archaeologist Harold Gladwin
Harold S. Gladwin
Harold Sterling Gladwin was an American archaeologist, anthropologist and stockbroker born in New York City.-Introduction:Harold Sterling Gladwin was an early twentieth century archaeologist that specialized in...
noted that nearby Navajo believe that the Anasazi built the roads to transport timber; archaeologist Neil Judd
Neil Judd
Neil Merton Judd was an American archaeologist who studied under the pioneering archaeologist of the American Southwest, Edgar Lee Hewett. He was curator of archaeology at the erstwhile United States National Museum, which later became part of the Smithsonian Institution...
offered a similar hypothesis.
"Sun Dagger"
Several parties have advanced the following contested theory: that at least twelve of the fourteen principal Chacoan complexes were sited and aligned in coordination, and that each was oriented along axes that mirrored the passing of the SunSun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
and Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
at visually pivotal times. Chaco's suspected role as a regional center of pilgrimage, where priestly elites staged the ritual smashing of pots—which over time built up at least one hillock composed solely of shards—is thought to underscore this pattern. Two whorl-shaped etchings near the top of Fajada Butte compose the "Sun Dagger" petroglyph, itself tucked behind the eponymous rock panels of the "Three-Slab Site". They are symbolically focal.
It consists of two spirals: one principal and one ancillary. The latter left-hand spiral captured both spring and fall equinoxes; its artifice was revealed by a descending spear of light, itself filtered through the slabs, that shined upon it and split it in two. The former and larger whorl to its right was lit by the titular "sun dagger", which bisected it through another interplay of slab and sun. It struck it, brilliantly, as the summer sun attains its solstice midday peak. The Chacoans were said to be marking, as artist, "Sun Dagger" discoverer, and leading proponent Anna Sofaer puts it, "the middle of time". Each turn of the 9.25-turn large spiral was found to mark one year in the 18.6-year "lunar excursion cycle" of the rising mid-winter full moon. This record is kept by a slab-cast lunar shadow whose edge strikes in succession each ring. As the full "minimum moon" closest to the winter solstice rises, the shadow's edge precisely strikes the center of the larger spiral; it steps outward year by year, ring by ring, until it strikes the outermost edge of it during the full "maximum moon", again in mid-winter.
Fajada Butte bears five other petroglyphs—including a carving of a "rattlesnake", other spirals, and a rectangle—that are conspicuously lit by contrasts between sunbeams and shadows during equinoxes or solstices. Public access to the butte was curtailed when, in 1989, erosion from modern foot traffic was found to be responsible for one of the three screening slabs at the "Sun Dagger" site shifting out of its ancient position; the assemblage of stones has thus lost some of its former spatial and temporal precision as a solar and lunar calendar. In 1990 the screens were stabilized and placed under observation, but the wayward slab was not moved back into its original orientation.
Alignments
The first Great House known to evince fastidious proportioning and alignment was Casa Rinconada: the twinned "T"-shaped portals of its 10 m (33 ft)-radius great kiva were north-south collinear, and axes joining opposing windows passed within 10 cm (4 in) of its center. The Great Houses of Pueblo Bonito and Chetro Ketl were found by the "Solstice Project" and the U.S. National Geodetic SurveyU.S. National Geodetic Survey
National Geodetic Survey, formerly called the U.S. Coast and Geodetic Survey , is a United States federal agency that defines and manages a national coordinate system, providing the foundation for transportation and communication; mapping and charting; and a large number of applications of science...
to be sited along a precisely east-west line, an axis that captures the passage of the equinox
Equinox
An equinox occurs twice a year, when the tilt of the Earth's axis is inclined neither away from nor towards the Sun, the center of the Sun being in the same plane as the Earth's equator...
sun. The lines perpendicularly bisecting their principal walls are aligned north-south, implying a possible intent to mirror the equinox midday. Pueblo Alto and Tsin Kletsin are also north-south aligned. These two axes form an inverted cross when viewed from above; its northbound reach is extended another 35 mi (56 km) past Pueblo Alto by the ramrod-straight "Great North Road", a pilgrimage route which modern-day Pueblo Indians believe to be an allusion to myths surrounding their arrival from the distant north.
Two shared-latitude but diametrically opposed complexes located some 15 mi (24 km) from the core buildings of the central canyon, Pueblo Pintado and Kin Bineola, each lie on a path from the central canyon that is collinear with the passage and setting of the full mid-winter "minimum moon", which recurs every 18.6 years. Two other complexes less distant from Pueblo Bonito, Una Vida and Peñasco Blanco, share an axis collinear with the passage of the full "maximum moon". The terms "minimum" and "maximum" refer to the azimuthal extreme points in the lunar excursion cycle, or the swings in direction relative to true north that the setting full moon exhibits. It takes roughly 9.25 years for the rising or setting full moon nearest to winter solstice
Solstice
A solstice is an astronomical event that happens twice each year when the Sun's apparent position in the sky, as viewed from Earth, reaches its northernmost or southernmost extremes...
to proceed from its maximum azimuthal north, or "maximum extremum", to its southernmost azimuth, known as "minimum extremum".
Reasons for the alignments have been offered:
See also
- Ah-Shi-Sle-Pah Wilderness Study AreaAh-Shi-Sle-Pah Wilderness Study AreaAh-Shi-Sle-Pah Wilderness Study Area is located in San Juan County, New Mexico between Chaco Canyon and the De-Na-Zin Wilderness. The Wilderness Study Area has multicolored badlands, sandstone hoodoos, petrified wood and dinosaur bones, similar to those found in the nearby Bisti Badlands and...
- List of archaeoastronomical sites by country
- List of dwellings of Pueblo peoples
Further reading
External links
Official and academicImagery and travel
Other