The Salton Sink is the low point of an

endorheic basin An endorheic basin (; also spelled endoreic basin or endorreic basin) is a drainage basin that normally retains water and allows no outflow to other external bodies of water, such as rivers or oceans, but drainage converges instead into lakes ...

, a closed drainage system with no outflows to other bodies of water, in the Colorado Desert sub-region of the

Sonoran Desert The Sonoran Desert ( es, Desierto de Sonora) is a desert in North America and ecoregion that covers the northwestern Mexican states of Sonora, Baja California, and Baja California Sur, as well as part of the southwestern United States (in Ariz ...

. The sink falls within the larger

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 stat ...

and separates the Coachella Valley from 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 ...

, which are also segments of the Salton Trough. The lowest point of the sink is below sea level, and since 1906 the Salton Sea has filled the lowest portion of the sink to a water depth of up to .

Geology

The Salton Sink is the topographic low area within the

, 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. The Salton Trough is a result of crustal stretching and sinking 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 tectonic boundary between the Pacific Plate and the North American Plate, and its motion is right-lateral strike-slip (horizonta ...

and the East Pacific Rise. The Brawley seismic zone forms the southeast end of the basin and connects the San Andreas Fault system with the Imperial Fault Zone to the south. 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 ...

are rhyolite lava domes within the basin which were active 10,300 (± 1000) years BP.

History

A large lake, Lake Cahuilla, existed in the area from about 20,500 to 3,000 years ago and left evidence as wave-cut benches on the higher portions of the Salton Buttes. A beach mark outlines the shoreline of ancient Lake Cahuilla where archeologists found rockfish traps and charred remains of razorback sucker and bonytail bones. High water lines suggest the basin has filled many times, creating a lake some in length and nearly deep. Its most recent incarnation is evidenced by fish traps found some below the high-water mark that were estimated to be between 300 and 1,000 years old. In recent times, the 1862 Colorado River flood waters reached the Salton Sink, filling it and creating a lake some long and wide. In 1884 and 1891 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 ...

had escapement flow into the Salton Sink. The 1891 flood created a lake that covered an area long and wide. A larger 1905 Colorado flood escaped into a diversion canal, forming the Alamo and New Rivers and creating the current Salton Sea in the sink's Coachella Valley.“A Sea in the Making in the Southland“ in ''The Salton Sea California's Overlooked Treasure''
/ref> A 1907 dam prevents flood escapements, but leakage still occurs to the Salton Sea.

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References

{{California Faults, state=collapsed Endorheic basins of the United States Geography of the Colorado Desert Geography of Imperial County, California Geography of Riverside County, California Coachella Valley Imperial Valley Salton Sea Salton Trough Geology of Imperial County, California Geology of Riverside County, California