The Salton Trough is an active

tectonic Tectonics (; ) are the processes that control the structure and properties of the Earth's crust and its evolution through time. These include the processes of mountain building, the growth and behavior of the strong, old cores of continents ...

pull-apart basin, or

graben In geology, a graben () is a depressed block of the crust of a planet or moon, bordered by parallel normal faults. Etymology ''Graben'' is a loan word from German, meaning 'ditch' or 'trench'. The word was first used in the geologic contex ...

. It lies within the

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, Texa ...

Riverside Riverside may refer to: Places Australia * Riverside, Tasmania, a suburb of Launceston, Tasmania Canada * Riverside (electoral district), in the Yukon * Riverside, Calgary, a neighbourhood in Alberta * Riverside, Manitoba, a former rural m ...

, and

San Diego San Diego ( , ; ) is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the List of United States cities by population, eigh ...

counties of southeastern

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

and extends south of the

Mexico–United States border The Mexico–United States border ( es, frontera Estados Unidos–México) is an international border separating Mexico and the United States, extending from the Pacific Ocean in the west to the Gulf of Mexico in the east. The border traver ...

into the state of

Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

. The northwestern end of the trough starts at the

San Gorgonio Pass The San Gorgonio Pass, or Banning Pass, is a elevation gap on the rim of the Great Basin between the San Bernardino Mountains to the north and the San Jacinto Mountains to the south. The pass was formed by the San Andreas Fault, a major trans ...

in Riverside County, and extends southeast to the

Gulf of California The Gulf of California ( es, Golfo de California), also known as the Sea of Cortés (''Mar de Cortés'') or Sea of Cortez, or less commonly as the Vermilion Sea (''Mar Bermejo''), is a marginal sea of the Pacific Ocean that separates the Baja Ca ...

. Major geographical features located in the trough include the

Coachella Valley , map_image = Wpdms shdrlfi020l coachella valley.jpg , map_caption = Coachella Valley , location = California, United States , coordinates = , width = , boundaries = Salton Sea (southeast), Santa Rosa Mountains (southwest), San Jacint ...

, 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 Gulf o ...

, and the

Imperial Valley , photo = Salton Sea from Space.jpg , photo_caption = The Imperial Valley below the Salton Sea. The US-Mexican border runs diagonally across the lower left of the image. , map_image = Newriverwatershed-1-.jpg , map_caption = Map of Imperial ...

, in the United States, and the western side of the

Mexicali Valley Mexicali (; ) is the capital city of the Mexican state of Baja California. The city, seat of the Mexicali Municipality, has a population of 689,775, according to the 2010 census, while the Calexico–Mexicali metropolitan area is home to 1,000, ...

, and the

Colorado River Delta The Colorado River Delta is the region where the Colorado River flows into the Gulf of California (also known as the Sea of Cortez) in eastern Mexicali Municipality in the north of the state of Baja California in northwesternmost Mexico. The ...

in Mexico. The Salton Trough is a result of crustal stretching and sinking caused by the combined actions of the

San Andreas Fault The San Andreas Fault is a continental transform fault that extends roughly through California. It forms the tectonics, tectonic boundary between the Pacific Plate and the North American Plate, and its motion is Fault (geology)#Strike-slip fau ...

and the

East Pacific Rise The East Pacific Rise is a mid-ocean rise (termed an oceanic rise and not a mid-ocean ridge due to its higher rate of spreading that results in less elevation increase and more regular terrain), a divergent tectonic plate boundary located along ...

, particularly the

Gulf of California Rift Zone The Gulf of California Rift Zone (GCRZ) is the northernmost extension of the East Pacific Rise which extends some from the mouth of the Gulf of California to the southern terminus of the San Andreas Fault at the Salton Sink. The GCRZ is an incipi ...

(GCRZ), the northernmost portion of the East Pacific Rise. The GCRZ and the San Andreas Fault both terminate near the south end of the Salton Sea, in an area called the

Brawley Seismic Zone The Brawley Seismic Zone (BSZ), also known as the Brawley fault zone, is a predominantly extensional tectonic zone that connects the southern terminus of the San Andreas Fault with the Imperial Fault in Southern California. The BSZ is named for ...

. The Brawley seismic zone is an active spreading center that connects the San Andreas Fault system with the

Imperial Fault Zone The Imperial Fault Zone is a system of geological faults located in Imperial County in the Southern California region, and adjacent Baja California state in Mexico. It cuts across the border between the United States and Mexico. Geology The Im ...

to the south. The Salton Trough is also referred to as a

sedimentary basin Sedimentary basins are region-scale depressions of the Earth's crust where subsidence has occurred and a thick sequence of sediments have accumulated to form a large three-dimensional body of sedimentary rock. They form when long-term subsidence ...

because the basin has filled with sedimentary deposits as quickly as the basin has been sinking. In some areas, the sediment is more than deep. Sources of the sediment are the mountainous areas that surround the trough, 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 drainage basin, watershed that encompasses parts of ...

, which in the past fed

Lake Cahuilla Lake Cahuilla ( ; also known as Lake LeConte and Blake Sea) was a prehistoric lake in California and northern Mexico. Located in the Coachella and Imperial valleys, it covered surface areas of to a height of above sea level during the Holoce ...

, a large inland freshwater lake, that disappeared after the Colorado River changed course to the Gulf of California.

Facts about the Salton Trough

*At below sea level, the

Salton Sink The Salton Sink is the low point of an endorheic basin, a closed drainage system with no outflows to other bodies of water, in the Colorado Desert sub-region of the Sonoran Desert. The sink falls within the larger Salton Trough and separates the ...

is the topographic low area within the Salton Trough, and is the second-lowest point, after

Death Valley Death Valley is a desert valley in Eastern California, in the northern Mojave Desert, bordering the Great Basin Desert. During summer, it is the Highest temperature recorded on Earth, hottest place on Earth. Death Valley's Badwater Basin is the ...

, on the

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

n continent. At the

, which fills the lowest part of the Salton Sink, is the lowest lake in North America. *The Salton Trough is commonly subject to migrating earthquake swarms. *The

Salton Buttes The Salton Buttes are a group of volcanoes in California, on the Salton Sea. They consist of a -long row of five lava domes, named Mullet Island, North Red Hill, Obsidian Butte, Rock Hill and South Red Hill. They are closely associated with a ...

, located within the Salton Sea, are

rhyolite Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral ...

lava dome In volcanology, a lava dome is a circular mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano. Dome-building eruptions are common, particularly in convergent plate boundary settings. Around 6% of eruptions on ...

s within the basin which were active 10,300 (± 1000) years BP. *Within the field of

Physical Geography Physical geography (also known as physiography) is one of the three main branches of geography. Physical geography is the branch of natural science which deals with the processes and patterns in the natural environment such as the atmosphere, h ...

the Salton Trough is classified as a distinct section of the

Basin and Range province The Basin and Range Province is a vast physiographic region covering much of the inland Western United States and northwestern Mexico. It is defined by unique basin and range topography, characterized by abrupt changes in elevation, alternating ...

within the Intermontane Plateaus division of the American Landmass. * The

Niland Geyser Niland Geyser (nicknamed the "Slow One" and formally designated W9) is a moving mud pot or mud spring outside Niland, California in the Salton Trough in an area of geological instability due to the San Andreas fault, formed due to carbon dioxide be ...

is one of dozens of mud pots and mud volcanoes in the Salton Trough, but is the only one in the world known to have moved significantly, affecting the

Union Pacific Railroad The Union Pacific Railroad , legally Union Pacific Railroad Company and often called simply Union Pacific, is a freight-hauling railroad that operates 8,300 locomotives over routes in 23 U.S. states west of Chicago and New Orleans. Union Paci ...

, California State Route 111, and other infrastructure since 2018.

References

Pull-apart basins Colorado Desert Geologic provinces of California Geology of Imperial County, California Geology of Riverside County, California Geology of San Diego County, California Geological depressions in the United States Physiographic sections Physiographic regions of the United States *Trough Geography of Baja California {{US-geology-stub