Riverside Mountains
Encyclopedia
The Riverside Mountains are a mountain range in Riverside County
, California
. The town of Vidal, California
is located in the West Riverside Mountains
.
, in the Lower Colorado River Valley
region. They are southeast of the Turtle Mountains
and north of the Big Maria Mountains
, and the Colorado River
borders its eastern perimeter. The high point of the range is 2252 feet (686 m).
. The Colorado River parallels this wilderness on its eastern edge.
The landscape varies from gently sloping bajadas
to steep, rugged interiors. Washes emerging from canyons divide the bajadas below. Numerous peaks in the Riverside Mountains give this small range a rough, craggy appearance. Two sensitive plant species, the foxtail cactus and California barrel cactus
; and a small herd of Burro deer
(Odocoileus hemionus eremicus) live in the Riverside range.
(MFTB). The Maria Fold and Thrust Belt underwent generally thick-skinned
(involving basement rocks) North-South trending crustal shortening in the Cretaceous
. The structures of the MFTB are exposed by to later generally East-West
trending large-scale crustal extension in the Miocene
, through what is known to geologists as the Colorado River Extensional Corridor. This North-South shortening is anomalous, as crustal shortening in the rest of the North American Cordillera
is oriented generally East-West because of the generally East-West compression that was due to the subduction of the Farallon plate
under western North America. Also unlike the rest of the North American Cordillera, deformation in the Maria Fold and Thrust Belt involved rocks of the North American Craton, most notably the Grand Canyon sequence
of sedimentary rocks.
and metamorphic core complex
system as a result of the Miocene
-age extension. The lower plate consists of a stack of metamorphosed units, which comprise Jurassic
metavolcanics, the metamorphosed Grand Canyon sequence, the metamorphosed McCoy Mountains
Formation and related Mesozoic
rocks, and the Precambrian
basement. The upper plate of the detachment fault consists of a small sedimentary basin
containing Tertiary
-age syntectonic (deposited during tectonic activity) volcanic units, conglomerates
, and other sedimentary rock
s.
Riverside County, California
Riverside County is a county in the U.S. state of California. One of 58 California counties, it covers in the southern part of the state, and stretches from Orange County to the Colorado River, which forms the state border with Arizona. The county derives its name from the city of Riverside,...
, California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
. The town of Vidal, California
Vidal, California
Vidal, California is a small Unincorporated community located in southeastern California, in San Bernardino County on U.S. Route 95, north of Blythe, California and south of Needles. The town is west of the townsite of Earp, California and west of Parker, Arizona on State Highway 62. The town...
is located in the West Riverside Mountains
West Riverside Mountains
The West Riverside Mountains are a mountain range in Riverside County, California....
.
Geography
The Riverside Mountains are in the Colorado DesertColorado Desert
California's Colorado Desert is a part of the larger Sonoran Desert, which extends across southwest North America. The Colorado Desert region encompasses approximately , reaching from the Mexican border in the south to the higher-elevation Mojave Desert in the north and from the Colorado River in...
, in the Lower Colorado River Valley
Lower Colorado River Valley
The Lower Colorado River Valley is the river region of the lower Colorado River of the southwestern United States in North America that rises in the Rocky Mountains and has its outlet at the Colorado River Delta in the northern Sea of Cortez in northwestern Mexico, between the states of Baja...
region. They are southeast of the Turtle Mountains
Turtle Mountains (California)
The Turtle Mountains, and Amat 'Achii'ar in the Mojave language, are located in San Bernardino County, California, in the southeastern part of the state.-Geography:The Turtle Mountains are southeast of Needles, California, west off of U.S...
and north of the Big Maria Mountains
Big Maria Mountains
The Big Maria Mountains are located in the southeastern part of the U.S. state of California, near the Colorado River and Arizona. The range lies between Blythe and Vidal, and west of U.S. Route 95 in California. The mountains are home to the Eagle Nest Mine and reach an elevation of 1,030 meters,...
, and the Colorado River
Colorado River
The Colorado River , is a river in the Southwestern United States and northwestern Mexico, approximately long, draining a part of the arid regions on the western slope of the Rocky Mountains. The watershed of the Colorado River covers in parts of seven U.S. states and two Mexican states...
borders its eastern perimeter. The high point of the range is 2252 feet (686 m).
Riverside Mountains Wilderness Area
The Riverside Mountains Wilderness Area is managed by the Bureau of Land ManagementBureau 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...
. The Colorado River parallels this wilderness on its eastern edge.
The landscape varies from gently sloping bajadas
Alluvial fan
An alluvial fan is a fan-shaped deposit formed where a fast flowing stream flattens, slows, and spreads typically at the exit of a canyon onto a flatter plain. A convergence of neighboring alluvial fans into a single apron of deposits against a slope is called a bajada, or compound alluvial...
to steep, rugged interiors. Washes emerging from canyons divide the bajadas below. Numerous peaks in the Riverside Mountains give this small range a rough, craggy appearance. Two sensitive plant species, the foxtail cactus and California barrel cactus
Barrel cactus
Barrel cacti are classified into the two genera Echinocactus and Ferocactus, both of which are found in the Southwest Desert of North America. Their pineapple-shaped fruits can be easily removed but are not recommended for eating. The barrel cactus may reach over a metre in height. Its ribs are...
; and a small herd of Burro 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...
(Odocoileus hemionus eremicus) live in the Riverside range.
Maria Fold and Thrust Belt
The Riverside Mountains are one of several ranges that constitute the Maria Fold and Thrust BeltMaria Fold and Thrust Belt
The Maria fold and thrust belt is a portion of the North American Cordillera orogen in which geological structures accommodate roughly north-south to northwest-southeast vergent Mesozoic age crustal shortening. This lies in contrast to the remainder of the Cordillera, in which shortening is...
(MFTB). The Maria Fold and Thrust Belt underwent generally thick-skinned
Thick-skinned deformation
Thick-skinned deformation is a geological term which refers to crustal shortening that involves basement rocks and deep-seated faults. Crustal shortening occurs when the region is undergoing horizontal compression. This occurs in orogenesis, or mountain building, during which the crust is shortened...
(involving basement rocks) North-South trending crustal shortening in 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...
. The structures of the MFTB are exposed by to later generally East-West
East-West
-Side two:-Personnel:* Paul Butterfield — vocals, harmonica* Mike Bloomfield — electric guitar* Elvin Bishop — electric guitar, lead vocal on "Never Say No"* Mark Naftalin — piano, organ* Jerome Arnold — bass...
trending large-scale crustal extension in 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...
, through what is known to geologists as the Colorado River Extensional Corridor. This North-South shortening is anomalous, as crustal shortening in the rest of the North American Cordillera
North American Cordillera
The North American Cordillera is the North American portion of the American Cordillera which is a cordillera extending up and down the western side of the Americas. The North American Cordillera covers an extensive area of mountain ranges, intermontane basins, and plateaus in western North...
is oriented generally East-West because of the generally East-West compression that was due to the subduction of the Farallon plate
Farallon Plate
The Farallon Plate was an ancient oceanic plate, which began subducting under the west coast of the North American Plate— then located in modern Utah— as Pangaea broke apart during the Jurassic Period...
under western North America. Also unlike the rest of the North American Cordillera, deformation in the Maria Fold and Thrust Belt involved rocks of the North American Craton, most notably the Grand Canyon sequence
Geology of the Grand Canyon area
The geology of the Grand Canyon area exposes one of the most complete and studied sequences of rock on Earth. The nearly 40 major sedimentary rock layers exposed in the Grand Canyon and in the Grand Canyon National Park area range in age from about 200 million to nearly 2 billion years old...
of sedimentary rocks.
Rocks
The Riverside Mountains contain rocks from both the lower and upper plates of a large detachment faultDetachment fault
Detachment faulting is associated with large-scale extensional tectonics. Detachment faults often have very large displacements and juxtapose unmetamorphosed hanging walls against medium to high-grade metamorphic footwalls that are called metamorphic core complexes...
and metamorphic core complex
Metamorphic core complex
Metamorphic core complexes are exposures of deep crust exhumed in association with largely amagmatic extension. They form, and are exhumed, through relatively fast transport of middle and lower continental crust to the Earth's surface...
system as a result of 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...
-age extension. The lower plate consists of a stack of metamorphosed units, which comprise Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
metavolcanics, the metamorphosed Grand Canyon sequence, the metamorphosed McCoy Mountains
McCoy Mountains
The McCoy Mountains are located in southeastern California in the United States.-Geography:The range lies in a northwest-southeasterly direction east of the Palen Mountains and south of the Little Maria Mountains...
Formation and related Mesozoic
Mesozoic
The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...
rocks, and the Precambrian
Precambrian
The Precambrian is the name which describes the large span of time in Earth's history before the current Phanerozoic Eon, and is a Supereon divided into several eons of the geologic time scale...
basement. The upper plate of the detachment fault consists of a small sedimentary basin
Sedimentary basin
The term sedimentary basin is used to refer to any geographical feature exhibiting subsidence and consequent infilling by sedimentation. As the sediments are buried, they are subjected to increasing pressure and begin the process of lithification...
containing Tertiary
Tertiary
The Tertiary is a deprecated term for a geologic period 65 million to 2.6 million years ago. The Tertiary covered the time span between the superseded Secondary period and the Quaternary...
-age syntectonic (deposited during tectonic activity) volcanic units, conglomerates
Conglomerate (geology)
A conglomerate is a rock consisting of individual clasts within a finer-grained matrix that have become cemented together. Conglomerates are sedimentary rocks consisting of rounded fragments and are thus differentiated from breccias, which consist of angular clasts...
, and other sedimentary rock
Sedimentary rock
Sedimentary rock are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles to settle and accumulate or minerals to precipitate from a solution....
s.
See also
- Category: Flora of the California desert regions
- Category: Protected areas of the Colorado Desert
- Category: Wilderness Areas within the Lower Colorado River Valley
- Category: Bureau of Land Management areas in California
