Lake Corcoran (also known as Lake Clyde, after

Clyde Wahrhaftig Clyde A. Wahrhaftig (December 1, 1919April 6, 1994) was an American geologist who worked for the United States Geological Survey and taught at the University of California at Berkeley. His research areas included Alaska, the Sierra Nevada, and th ...

, an American

geophysicist Geophysics () is a subject of natural science concerned with the physical processes and physical properties of the Earth and its surrounding space environment, and the use of quantitative methods for their analysis. The term ''geophysics'' som ...

) is an ancient lake that covered the Central Valley of

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 ...

The lake existed in the valleys of the

Sacramento River The Sacramento River ( es, Río Sacramento) is the principal river of Northern California in the United States and is the largest river in California. Rising in the Klamath Mountains, the river flows south for before reaching the Sacramento–S ...

and the

San Joaquin River The San Joaquin River (; es, Río San Joaquín) is the longest river of Central California. The long river starts in the high Sierra Nevada, and flows through the rich agricultural region of the northern San Joaquin Valley before reaching Suis ...

, at least as far north as the

Sutter Buttes The Sutter Buttes (Maidu: ''Histum Yani'' or ''Esto Yamani'', Wintun: ''Olonai-Tol'', Nisenan: ''Estom Yanim'') are a small circular complex of eroded volcanic lava domes which rise as buttes above the flat plains of the Sacramento Valley in Sut ...

. If so, it might have had a size comparable to

Lake Michigan Lake Michigan is one of the five Great Lakes of North America. It is the second-largest of the Great Lakes by volume () and the third-largest by surface area (), after Lake Superior and Lake Huron. To the east, its basin is conjoined with that o ...

. An alternate view presumes that the lake covered only the southern parts of the Central Valley. The total surface covered by the lake amounts to about .

Buena Vista Lake Buena Vista Lake was a fresh-water lake in Kern County, California, in the Tulare Lake Basin in the southern San Joaquin Valley, California. Buena Vista Lake was the second largest of several similar lakes in the Tulare Lake basin, and was fed ...

, Kern Lake and

Tulare Lake Tulare Lake () (Spanish: ''Laguna de Tache'', Yokuts: ''Pah-áh-su'') is a freshwater dry lake with residual wetlands and marshes in the southern San Joaquin Valley, California, United States. After Lake Cahuilla disappeared in the 17th century ...

are remnants of Lake Corcoran. The lake is the source of the Corcoran Clay, a

lacustrine A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much larger ...

unit Unit may refer to: Arts and entertainment * UNIT, a fictional military organization in the science fiction television series ''Doctor Who'' * Unit of action, a discrete piece of action (or beat) in a theatrical presentation Music * ''Unit'' (alb ...

of the Tulare and Turlock Lake formations. It also influenced

sedimentation Sedimentation is the deposition of sediments. It takes place when particles in suspension settle out of the fluid in which they are entrained and come to rest against a barrier. This is due to their motion through the fluid in response to the ...

off the coast of California. The lake existed between about 758,000 and 665,000 years ago. Clay deposition rates indicate that the lake lasted for 50,000 to 100,000 years, and it underwent about 15 dry-wet cycles. The

Lava Creek Tuff The Lava Creek Tuff is a tuff formation in Wyoming, Montana and Idaho, United States, created during the Lava Creek eruption around 630,000 years ago, which formed the Yellowstone Caldera. The Lava Creek Tuff is distributed in a radial pattern ar ...

Yellowstone Caldera The Yellowstone Caldera, sometimes referred to as the Yellowstone Supervolcano, is a volcanic caldera and supervolcano in Yellowstone National Park in the Western United States. The caldera and most of the park are located in the northwest corn ...

and the Bishop Tuff of the

Long Valley Caldera Long Valley Caldera is a depression in eastern California that is adjacent to Mammoth Mountain. The valley is one of the Earth's largest calderas, measuring about long (east-west), wide (north-south), and up to deep. Long Valley was formed 7 ...

were deposited in the Corcoran Clay. Before Lake Corcoran formed, the Central Valley was a

bay A bay is a recessed, coastal body of water that directly connects to a larger main body of water, such as an ocean, a lake, or another bay. A large bay is usually called a Gulf (geography), gulf, sea, sound (geography), sound, or bight (geogra ...

open to the south via a passage, until 2 million years ago when the bay was separated from the ocean, probably due to northwestward movement of the

Coast Ranges The Pacific Coast Ranges (officially gazetted as the Pacific Mountain System in the United States) are the series of mountain ranges that stretch along the West Coast of North America from Alaska south to Northern and Central Mexico. Although the ...

along 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 ...

. Subsequently, the valley was no longer a bay and alternately drained and filled with water. The factors contributing to the formation of Lake Corcoran are not fully understood but it appears that Great Valley drainage for most of the Miocene was to the south. The lake originally drained into

Monterey Bay Monterey Bay is a bay of the Pacific Ocean located on the coast of the U.S. state of California, south of the San Francisco Bay Area and its major city at the south of the bay, San Jose. San Francisco itself is further north along the coast, by a ...

or at times not at all.

Evaporation Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. High concentration of the evaporating substance in the surrounding gas significantly slows down evaporation, such as when humidi ...

from this lake was a source of water for the

Sierra Nevada The Sierra Nevada () is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primarily ...

and in lesser measure for 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 ...

behind it. This contributed to the formation of large

pluvial lake A pluvial lake is a body of water that accumulated in a basin because of a greater moisture availability resulting from changes in temperature and/or precipitation. These intervals of greater moisture availability are not always contemporaneous ...

s in

Nevada Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. N ...

. 600,000 years ago a new outlet formed in the present day

San Francisco Bay San Francisco Bay is a large tidal estuary in the U.S. state of California, and gives its name to the San Francisco Bay Area. It is dominated by the big cities of San Francisco, San Jose, and Oakland. San Francisco Bay drains water from a ...

, where it remains today. Sediments found south of San Francisco indicate that by 400,000 years ago the drainage was fully established. The overflow may have occurred at a time where

glacier A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its Ablation#Glaciology, ablation over many years, often Century, centuries. It acquires dis ...

s were melting and when shifts in the

jet stream Jet streams are fast flowing, narrow, meandering thermal wind, air currents in the Atmosphere of Earth, atmospheres of some planets, including Earth. On Earth, the main jet streams are located near the altitude of the tropopause and are west ...

during the marine oxygen isotope stage 6 caused increased precipitation in and runoff to the Central Valley. The overflow rapidly carved an outlet through

Carquinez Strait The Carquinez Strait (; Spanish: ''Estrecho de Carquinez'') is a narrow tidal strait in Northern California. It is part of the tidal estuary of the Sacramento and the San Joaquin rivers as they drain into the San Francisco Bay. The strait is lo ...

, probably catastrophically, and drained the lake. The Upper Turbidite Unit of the Monterey submarine fan may have formed soon after this outflow, when sediment from the former lake was carried out of its new outlet and down to

longshore drift Longshore drift from longshore current is a geological process that consists of the transportation of sediments (clay, silt, pebbles, sand, shingle) along a coast parallel to the shoreline, which is dependent on the angle incoming wave direction ...

References

Sources

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Corcoran Corcoran is an Irish surname, the original Irish language form being meaning 'descendant of Corcrán'. The name itself is derived from meaning 'purple'. History The name Corcoran is an anglicisation of the names of two Gaelic clans. The f ...

Pleistocene California Geography of the Sacramento Valley Geography of the San Joaquin Valley History of the San Joaquin Valley L Corcoran, California