Abert Rim
Encyclopedia
Abert Rim in Lake County
, Oregon
is one of the highest fault scarp
s in the United States. It rises 760 meters (2500 ft) above the valley floor, finishing with an 250-meter (800 ft) sheer-sided basalt
cap. It was formed during the Miocene
epoch. At that time basalt
ic flood lavas
covered much of eastern Oregon
. In subsequent faulting, great blocks were tilted and Abert Rim is at the western end of one of these blocks, while Lake Abert
lies on top of another. Stretching more than 48 kilometres (29.8 mi) from Lakeview
north to Alkali Lake, Abert Rim is also the longest exposed fault scarp
in North America.
Bighorn sheep
were transplanted to the rim in 1975 and 1977 from nearby Hart Mountain
, and are often spotted from the Abert Rim geologic point of interest sign located along Highway 395. Raptors, such as the Ferruginous Hawk
, are also common in the area.
The Chewaucan River
enters the lake from the south, however it has no outlet. The lake level varies depending on rainfall and it nearly completely dried up 140 years ago. It is one of the Great Basin
lakes.
The escarpment and lake were first mapped on December 20, 1843 by John C. Frémont
who named it after Colonel John James Abert
, his commanding officer.
The southern section of Abert Rim is a popular spot for hang gliding
because of the frequent thermal
s created by warm valley air rising up against the cliffs. The area is considered by many to be the hang gliding capital of the West. National hang gliding festivals are held each year in late June and during the Fourth of July.
Lake County, Oregon
Lake County is a county in the high desert south central region of the U.S. state of Oregon, so named for the many lakes found within its boundaries, including Lake Abert, Hart Lake Reservoir, and Goose Lake. While Lake is among Oregon's largest counties, it is sparsely populated with 7,895...
, Oregon
Oregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
is one of the highest fault scarp
Fault scarp
A fault scarp is the topographic expression of faulting attributed to the displacement of the land surface by movement along faults. They are exhibited either by differential movement and subsequent erosion along an old inactive geologic fault , or by a movement on a recent active fault...
s in the United States. It rises 760 meters (2500 ft) above the valley floor, finishing with an 250-meter (800 ft) sheer-sided basalt
Basalt
Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...
cap. It was formed during the Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
epoch. At that time basalt
Basalt
Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...
ic flood lavas
Flood basalt
A flood basalt or trap basalt is the result of a giant volcanic eruption or series of eruptions that coats large stretches of land or the ocean floor with basalt lava. Flood basalts have occurred on continental scales in prehistory, creating great plateaus and mountain ranges...
covered much of eastern Oregon
Eastern Oregon
Eastern Oregon is the eastern part of the U.S. state of Oregon. It is not an officially recognized geographic entity, thus the boundaries of the region vary according to context. It is sometimes understood to include only the eight easternmost counties in the state; in other contexts, it includes...
. In subsequent faulting, great blocks were tilted and Abert Rim is at the western end of one of these blocks, while Lake Abert
Lake Abert
Lake Abert is a large, shallow, alkali lake in Lake County, Oregon, United States. It is approximately long and wide at its widest point. It is located northwest of the small, unincorporated community of Valley Falls, Oregon. The lake was named in honor of Colonel John James Abert by explorer...
lies on top of another. Stretching more than 48 kilometres (29.8 mi) from Lakeview
Lakeview, Oregon
Lakeview is a city in Lake County, Oregon, United States. The population was 2,294 at the 2010 census. It is the county seat of Lake County. Although it is an incorporated city, the municipal government refers to the community as "The Town of Lakeview", and bills itself as "Tallest Town in Oregon"...
north to Alkali Lake, Abert Rim is also the longest exposed fault scarp
Fault scarp
A fault scarp is the topographic expression of faulting attributed to the displacement of the land surface by movement along faults. They are exhibited either by differential movement and subsequent erosion along an old inactive geologic fault , or by a movement on a recent active fault...
in North America.
Bighorn sheep
Bighorn Sheep
The bighorn sheep is a species of sheep in North America named for its large horns. These horns can weigh up to , while the sheep themselves weigh up to . Recent genetic testing indicates that there are three distinct subspecies of Ovis canadensis, one of which is endangered: Ovis canadensis sierrae...
were transplanted to the rim in 1975 and 1977 from nearby Hart Mountain
Hart Mountain
Hart Mountain is a fault-block mountain, in Lake County, Oregon, USA. It lies about to the east of Lakeview.It is sometimes confused with a mountain range, but is more properly described as one mountain. The two highest peaks are Warner Peak and Hart Peak.The top of the mountain is part of the...
, and are often spotted from the Abert Rim geologic point of interest sign located along Highway 395. Raptors, such as the Ferruginous Hawk
Ferruginous Hawk
The Ferruginous Hawk , Buteo regalis , is a large bird of prey. It is not a true hawk like sparrowhawks or goshawks, but rather belongs to the broad-winged buteo hawks, known as "buzzards" in Europe...
, are also common in the area.
The Chewaucan River
Chewaucan River
The Chewaucan River is part of the Great Basin drainage. It flows through the Fremont–Winema National Forests, Bureau of Land Management land, and private property in southern Oregon. Its watershed consists of of conifer forest, marsh, and rural pasture land...
enters the lake from the south, however it has no outlet. The lake level varies depending on rainfall and it nearly completely dried up 140 years ago. It is one of the Great Basin
Great Basin
The Great Basin is the largest area of contiguous endorheic watersheds in North America and is noted for its arid conditions and Basin and Range topography that varies from the North American low point at Badwater Basin to the highest point of the contiguous United States, less than away at the...
lakes.
The escarpment and lake were first mapped on December 20, 1843 by John C. Frémont
John C. Frémont
John Charles Frémont , was an American military officer, explorer, and the first candidate of the anti-slavery Republican Party for the office of President of the United States. During the 1840s, that era's penny press accorded Frémont the sobriquet The Pathfinder...
who named it after Colonel John James Abert
John James Abert
John James Abert was a United States soldier. He headed the Corps of Topographical Engineers for 32 years, during which time he organized the mapping of the American West....
, his commanding officer.
The southern section of Abert Rim is a popular spot for hang gliding
Hang gliding
Hang gliding is an air sport in which a pilot flies a light and unmotorized foot-launchable aircraft called a hang glider ....
because of the frequent thermal
Thermal
A thermal column is a column of rising air in the lower altitudes of the Earth's atmosphere. Thermals are created by the uneven heating of the Earth's surface from solar radiation, and are an example of convection. The sun warms the ground, which in turn warms the air directly above it...
s created by warm valley air rising up against the cliffs. The area is considered by many to be the hang gliding capital of the West. National hang gliding festivals are held each year in late June and during the Fourth of July.