The Mono Basin is an

endorheic 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 ...

drainage basin A drainage basin is an area of land where all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, ...

located east of

Yosemite National Park Yosemite National Park ( ) is an American national park in California, surrounded on the southeast by Sierra National Forest and on the northwest by Stanislaus National Forest. The park is managed by the National Park Service and covers an ...

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 ...

and

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 ...

. It is bordered to the west by 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 primar ...

, to the east by the Cowtrack Mountains, to the north by the

Bodie Hills The Bodie Hills are a low mountain range in Mono County, California, in the United States. The Bodie Hills are between Bridgeport and the Nevada border, where they become the Bodie Mountains in Mineral County, Nevada. The Sierra Nevada lies to t ...

, and to the south by the north ridge of the Long Valley Caldera.Mono Basin, Mono County, California
/ref> Estimates of the size of the basin range from 634 to 801 square miles, and the basin's elevation ranges from around 6,380 feet (level of

Mono Lake Mono Lake ( ) is a saline soda lake in Mono County, California, formed at least 760,000 years ago as a terminal lake in an endorheic basin. The lack of an outlet causes high levels of salts to accumulate in the lake which make its water a ...

as of 1986) to 13,061 feet atop

Mount Dana Mount Dana is a mountain in the U.S. state of California. Its summit marks the eastern boundary of Yosemite National Park and the western boundary of the Ansel Adams Wilderness. At an elevation of , it is the second highest mountain in Yosemit ...

near the

Sierra Crest The Sierra Crest is a roughly generally north-to-south ridgeline that demarcates the broad west and narrow east slopes of the Sierra Nevada and that extends as far east as the Sierra's topographic front (e.g., Diamond Mountains and Sierran e ...

. Notable features in the basin include

and the Mono-Inyo Craters, as well as the town of Lee Vining.

Geology

Geologically the basin is a

structural basin A structural basin is a large-scale structural formation of rock strata formed by tectonic warping of previously flat-lying strata. They are geological depressions, the inverse of domes. Elongated structural basins are also known as syncline ...

that is bordered to the west by the frontal fault of the Sierra Nevada. The basin is part of the

Walker Lane The Walker Lane is a geologic trough roughly aligned with the California/Nevada border southward to where Death Valley intersects the Garlock Fault, a major left lateral, or sinistral, strike-slip fault. The north-northwest end of the Walker L ...

, an area where much of the deformation between the

North American Plate The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of , it is the Earth's second largest tectonic plate, behind the Paci ...

and the

Pacific Plate The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At , it is the largest tectonic plate. The plate first came into existence 190 million years ago, at the triple junction between the Farallon, Phoenix, and I ...

occurs. The basin was created by geological forces over the last five million years by crustal stretching 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 ...

and associated

volcanism Volcanism, vulcanism or volcanicity is the phenomenon of eruption of molten rock (magma) onto the surface of the Earth or a solid-surface planet or moon, where lava, pyroclastics, and volcanic gases erupt through a break in the surface called a ...

and faulting at the base of the

. Five million years ago, the Sierra Nevada was an eroded set of rolling hills and Mono Basin and Owens Valley did not yet exist. From 4.5 to 2.6 million years ago, large volumes of

basalt Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90 ...

were erupted around what is now Cowtrack Mountain (east and south of Mono Basin); eventually covering and reaching a maximum thickness of . Later volcanism in the area occurred 3.8 million to 250,000 years ago. This activity was northwest of Mono Basin and included the formation of Aurora Crater, Beauty Peak, Cedar Hill (later an island in the highest stands of Mono Lake), and Mount Hicks. The area remains volcanically active today, with Paoha Island forming from volcanic activity 350 years ago.

Footnotes

References

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External links

Mono Lake Committee
{{Authority control Landforms of the Sierra Nevada (United States) Valleys of Mono County, California Valleys of California

Geology

See also

Footnotes

References

External links