The Chocolate Mountains of

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

are located in

Imperial Imperial is that which relates to an empire, emperor, or imperialism. Imperial or The Imperial may also refer to: Places United States * Imperial, California * Imperial, Missouri * Imperial, Nebraska * Imperial, Pennsylvania * Imperial, Texas ...

and Riverside counties in the

Colorado Desert California's Colorado Desert is a part of the larger Sonoran Desert. It encompasses approximately , including the heavily irrigated Coachella and Imperial valleys. It is home to many unique flora and fauna. Geography and geology The Colorado D ...

Southern California Southern California (commonly shortened to SoCal) is a geographic and cultural region that generally comprises the southern portion of the U.S. state of California. It includes the Los Angeles metropolitan area, the second most populous urban ...

. The mountains stretch more than 60 miles (100 km) in a northwest to southeast direction, and are located east of the

Salton Sea The Salton Sea is a shallow, landlocked, highly saline body of water in Riverside and Imperial counties at the southern end of the U.S. state of California. It lies on the San Andreas Fault within the Salton Trough that stretches to the Gul ...

and south and west of the

Chuckwalla Mountains The Chuckwalla Mountains are a mountain range in the transition zone between the Colorado Desert—Sonoran Desert and the Mojave Desert, climatically and vegetationally, in Riverside County of southern California. Geography The range spans abo ...

and the

Colorado River The Colorado River ( es, Río Colorado) is one of the principal rivers (along with the Rio Grande) in the Southwestern United States and northern Mexico. The river drains an expansive, arid watershed that encompasses parts of seven U.S. s ...

. To the northwest lie the Orocopia Mountains.

Geography

The Chocolate Mountains form the northeast boundary of the

Salton Trough The Salton Trough is an active tectonic pull-apart basin, or graben. It lies within the Imperial, Riverside, and San Diego counties of southeastern California, United States and extends south of the Mexico–United States border into the sta ...

extending as a narrow range some southeast from the Orocopia Mountains to the

valley.Singer, Eugene, ''Geology of the Imperial Valley''
/ref> The mountains are located about west of the Chocolate Mountains of

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...

, but the two ranges are not connected. The range reaches an elevation of 2,475 feet (754 m) at Mount Barrow, and serves as a

drainage divide A drainage divide, water divide, ridgeline, watershed, water parting or height of land is elevated terrain that separates neighboring drainage basins. On rugged land, the divide lies along topographical ridges, and may be in the form of a singl ...

for the

Salton Watershed Salton or Saltoun may refer to: Places * East Saltoun and West Saltoun, Scotland * Salton, North Yorkshire, England * Salton City, California * Salton Sea * Salton Sink * Salton Trough The Salton Trough is an active tectonic pull-apart basin, o ...

to the west. The mountains receive very little rainfall in a normal year, typically 4-6 inches (100 to 150 mm). The predominant natural plants are of the

creosote bush ''Larrea tridentata'', called creosote bush and greasewood as a plant, chaparral as a medicinal herb, and ''gobernadora'' (Spanish for "governess") in Mexico, due to its ability to secure more water by inhibiting the growth of nearby plants. In S ...

–white bursage community, and the mean annual temperature is about to .

Geology

The range is composed of Precambrian basement rocks and Orocopia Schist with

Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretace ...

granite intrusions. The range may have been formed by the collision of a microcontinental fragment with mainland Southern California during the Late Cretaceous. The collision is indicated by a

thrust fault A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks. Thrust geometry and nomenclature Reverse faults A thrust fault is a type of reverse fault that has a dip of 45 degrees or less. If ...

which emplaced

Proterozoic The Proterozoic () is a geological eon spanning the time interval from 2500 to 538.8million years ago. It is the most recent part of the Precambrian "supereon". It is also the longest eon of the Earth's geologic time scale, and it is subdivided i ...

and

rocks of

continental crust Continental crust is the layer of igneous, sedimentary, and metamorphic rocks that forms the geological continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called '' sial'' be ...

on top of the late Mesozoic Orocopia Schist which in turn was composed of oceanic sedimentary and volcanic rocks. The range was host to numerous small

gold Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile ...

workings in the 19th century with one, the Mesquite Mine to the east, continuing to be active into the 20th century.

History

The Bradshaw Trail passed by the side of the mountains, the first "euroamerican" route to the

from

Riverside, California Riverside is a city in and the county seat of Riverside County, California, United States, in the Inland Empire metropolitan area. It is named for its location beside the Santa Ana River. It is the most populous city in the Inland Empire an ...

Military closures

The mountain range is occupied by the

Chocolate Mountain Aerial Gunnery Range The Chocolate Mountain Aerial Gunnery Range (CMAGR) is a bombing range operated by the US Marine Corps located in southern California. United States. Range description The range is a

, an aerial and gunnery practice area used by the

United States Navy The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...

and

Marines Marines, or naval infantry, are typically a military force trained to operate in littoral zones in support of naval operations. Historically, tasks undertaken by marines have included helping maintain discipline and order aboard the ship (refl ...

. A large part of the Chocolate Mountains lies within the gunnery range, and is closed to the public.

Wilderness areas

Little Picacho Wilderness

At the southeastern end of the Chocolate Mountains range are two important wilderness areas. The first is the

Little Picacho Wilderness The Little Picacho Wilderness is a wilderness area under the jurisdiction of the Bureau of Land Management. The wilderness is found in a southeast extension of the Chocolate Mountains adjacent to the Colorado River, in the southeastern part of ...

, a 38,170 acre (154.5 km²) region of geological features and habitat protection under the direction of the

Bureau of Land Management The Bureau of Land Management (BLM) is an agency within the United States Department of the Interior responsible for administering federal lands. Headquartered in Washington DC, and with oversight over , it governs one eighth of the country's ...

. The preserve has within its boundaries the southern portion of the Chocolate Mountains. Elevations within this area range from 200 to . The topography, characterized by jutting spires and steep ridges, is quite dramatic. Ravines laced within the range gradually broaden into sandy, tree-lined washes. Slopes and plains are devoid of vegetation, instead covered with a desert pavement of angular cobbles. These rusty dark orange and brown colored cobbles stand out against the nearly white bottoms of the washes. It is also called the Little

Picacho Peak Wilderness Picacho Peak Wilderness is a U.S. wilderness area located on nearly of desert land in Imperial County, California, just west of the Arizona state line. The wilderness area is managed by the Bureau of Land Management The Bureau of Land Manag ...

Indian Pass Wilderness

The Indian Pass Wilderness Area is to the north with of open space. The

Indian Pass Wilderness The Indian Pass Wilderness is wilderness area under the administered by the Bureau of Land Management. The reserve is located in the very southeastern part of the Chocolate Mountains, in the southeastern part of California, just to the west of t ...

is a distinctive part of the Chocolate Mountains, a range which extends from south central Riverside County to the

near Yuma, Arizona. Quartz Peak is the highest point in the wilderness capped at . Jagged peaks and spires are sliced by mazes of twisting canyons which carry water from occasional desert cloudbursts into several tree-lined washes. One of these washes passes through the heart of the wilderness area, giving rise to the region's local name, "Julian Wash country." The area's proximity to the Colorado River and the Arizona Desert contribute to the presence of wildlife species not commonly found in the California Desert.Indian Pass
Retrieved June 22, 2010. At the southern end of the Chocolate Mountains at elevations from 200 to , the Indian Pass Wilderness preserve is located east of

Brawley, California Brawley (formerly, Braly) is a city in the Imperial Valley and within Imperial County, southern California, United States. The population was 24,953 at the 2010 census, up from 22,052 in 2000. The town has a significant cattle and feed indust ...

, and is also managed by the Bureau of Land Management. A herd of 25

desert bighorn sheep The desert bighorn sheep (''Ovis canadensis nelsoni'') is a subspecies of bighorn sheep (''Ovis canadensis'') that is native to the deserts of the United States' intermountain west and southwestern regions, as well as northwestern Mexico. The ...

reside in the wilderness area, along with "the Picacho feral horses," wild

burro The domestic donkey is a hoofed mammal in the family Equidae, the same family as the horse. It derives from the African wild ass, ''Equus africanus'', and may be classified either as a subspecies thereof, ''Equus africanus asinus'', or as a ...

s, and the native and endangered

desert tortoise The desert tortoise (''Gopherus agassizii''), is a species of tortoise in the Family (biology), family Testudinidae. The species is native to the Mojave Desert, Mojave and Sonoran Deserts of the southwestern United States and northwestern Mexic ...

and

spotted bat The spotted bat (''Euderma maculatum'') is a species of vesper bat and the only species of the genus ''Euderma''. Description The spotted bat was first described by zoologist Joel Asaph Allen from the American Museum of Natural History in 189 ...