Mono Basin | |
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![]() Mono Basin from near Conway Summit. | |
Floor elevation | 6,380 feet (1,940 m) |
Area | 631 to 801 square miles (1,630 to 2,070 km2) |
Depth | 6,680 feet (2,040 m) |
Geography | |
Location | Mono County, California, United States |
Borders on | W: Sierra Crest N: Bodie Hills E: Cowtrack Mountains S: Long Valley Caldera [1] |
Coordinates | 37°57′N118°57′W / 37.950°N 118.950°W [2] |
The Mono Basin is an endorheic drainage basin located east of Yosemite National Park in California and Nevada. [3] [4] It is bordered to the west by the Sierra Nevada, to the east by the Cowtrack Mountains, to the north by the Bodie Hills, and to the south by the north ridge of the Long Valley Caldera. [1]
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 as of 1986) to 13,061 feet atop Mount Dana near the Sierra Crest. [5] [6] [7]
Notable features in the basin include Mono Lake and the Mono-Inyo Craters, as well as the town of Lee Vining.
Geologically the basin is a structural basin that is bordered to the west by the frontal fault of the Sierra Nevada. The basin is part of the Walker Lane, an area where much of the deformation between the North American Plate and the Pacific Plate occurs. [8]
The basin was formed by geological forces over the last five million years: basin and range crustal stretching and associated volcanism and faulting at the base of the Sierra Nevada. [9] : 45
From 4.5 to 2.6 million years ago, large volumes of basalt were extruded around what is now Cowtrack Mountain (east and south of Mono Basin); eventually covering 300 square miles (780 km2) and reaching a maximum thickness of 600 feet (180 m). [9] : 45 Later volcanism in the area occurred 3.8 million to 250,000 years ago. [9] : 46 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.[ citation needed ]
Lake Russell was the prehistoric predecessor to Mono Lake, during the Pleistocene. Its shoreline reached the modern-day elevation of 2,280 metres (7,480 ft), about 330 metres (1,100 ft) higher than the present-day lake. As of 1.6 million years ago, Lake Russell discharged to the northeast, into the Walker River drainage. After the Long Valley Caldera eruption 760,000 years ago, Lake Russell discharged into Adobe Lake to the southeast, then into the Owens River, and eventually into Lake Manly in Death Valley. [10] Prominent shore lines of Lake Russell, called strandlines by geologists, can be seen west of Mono Lake. [11]
Mono Basin is currently geologically active. Volcanic activity is related to the Mono-Inyo Craters: the most recent eruption occurred 350 years ago, resulting in the formation of Paoha Island. [12] Panum Crater is an example of a combined rhyolite dome and cinder cone. [13]
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 alkaline.
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 20 mi (32 km) long (east-west), 11 mi (18 km) wide (north-south), and up to 3,000 ft (910 m) deep.
Mammoth Mountain is a lava dome complex partially located within the town of Mammoth Lakes, California, in the Inyo National Forest of Madera and Mono Counties. It is home to a large ski area primarily on the Mono County side.
Owens Valley is an arid valley of the Owens River in eastern California in the United States. It is located to the east of the Sierra Nevada, west of the White Mountains and Inyo Mountains, and north of the Mojave Desert. It sits on the west edge of the Great Basin. The mountain peaks on the West side reach above 14,000 feet (4,300 m) in elevation, while the floor of the Owens Valley is about 4,000 feet (1,200 m), making the valley the deepest in the United States. The Sierra Nevada casts the valley in a rain shadow, which makes Owens Valley "the Land of Little Rain". The bed of Owens Lake, now a predominantly dry endorheic alkali flat, sits on the southern end of the valley.
The Mono–Inyo Craters are a volcanic chain of craters, domes and lava flows in Mono County, Eastern California. The chain stretches 25 miles (40 km) from the northwest shore of Mono Lake to the south of Mammoth Mountain. The Mono Lake Volcanic Field forms the northernmost part of the chain and consists of two volcanic islands in the lake and one cinder cone volcano on its northwest shore. Most of the Mono Craters, which make up the bulk of the northern part of the Mono–Inyo chain, are phreatic volcanoes that have since been either plugged or over-topped by rhyolite domes and lava flows. The Inyo volcanic chain form much of the southern part of the chain and consist of phreatic explosion pits, and rhyolitic lava flows and domes. The southernmost part of the chain consists of fumaroles and explosion pits on Mammoth Mountain and a set of cinder cones south of the mountain; the latter are called the Red Cones.
The exposed geology of the Yosemite area includes primarily granitic rocks with some older metamorphic rock. The first rocks were laid down in Precambrian times, when the area around Yosemite National Park was on the edge of a very young North American continent. The sediment that formed the area first settled in the waters of a shallow sea, and compressive forces from a subduction zone in the mid-Paleozoic fused the seabed rocks and sediments, appending them to the continent. Heat generated from the subduction created island arcs of volcanoes that were also thrust into the area of the park. In time, the igneous and sedimentary rocks of the area were later heavily metamorphosed.
The Owens River is a river in eastern California in the United States, approximately 183 miles (295 km) long. It drains into and through the Owens Valley, an arid basin between the eastern slope of the Sierra Nevada and the western faces of the Inyo and White Mountains. The river terminates at the endorheic Owens Lake south of Lone Pine, at the bottom of a 2,600 sq mi (6,700 km2) watershed.
An active volcano is a volcano which is either erupting or is likely to erupt in the future. An active volcano which is not currently erupting is known as a dormant volcano.
The Coso Volcanic Field is located in Inyo County, California, at the western edge of the Basin and Range geologic province and northern region of the Mojave Desert. The Fossil Falls are part of the Coso Field, created by the prehistoric Owens River. They are within the Naval Air Weapons Station China Lake and northeast of Little Lake and U.S. Route 395.
Inyo National Forest is a United States National Forest covering parts of the eastern Sierra Nevada of California and the White Mountains of California and Nevada. The forest hosts several superlatives, including Mount Whitney, the highest point in the contiguous United States; Boundary Peak, the highest point in Nevada; and the Ancient Bristlecone Pine Forest, which protects the oldest living trees in the world. The forest, encompassing much of the Owens Valley, was established by Theodore Roosevelt as a way of sectioning off land to accommodate the Los Angeles Aqueduct project in 1907, making the Inyo National Forest one of the least wooded forests in the U.S. National Forest system.
Panum Crater is a volcanic cone that is part of the Mono–Inyo Craters, a chain of recent volcanic cones south of Mono Lake and east of the Sierra Nevada, in California, United States. Panum Crater is between 600 and 700 years old, and it exhibits all of the characteristics of the textbook rhyolitic lava dome.
Hot Creek, starting as Mammoth Creek, is a stream in Mono County of eastern California, in the Western United States. It is within the Inyo National Forest.
Glass Mountain, on the Inyo National Forest, is one of the tallest peaks in Mono County, California. The peak lies 20 miles (32 km) southeast of the shoreline of Mono Lake and is the highest point on the four-mile (6.4 km) long sinuous Glass Mountain Ridge.
The Red Cones are a pair of cinder cones near Devils Postpile National Monument, in eastern Madera County of central California. They are within the eastern Sierra Nevada and Inyo National Forest.
The California Volcano Observatory (CalVO) is the volcano observatory that monitors the volcanic and geologic activity of California and Nevada. It is a part of the Volcano Hazards Program of the United States Geological Survey, a scientific agency of the United States government.
The Mono Basin National Forest Scenic Area is a protected area in Eastern California that surrounds Mono Lake and the northern half of the Mono Craters volcanic field. It is administered by the Inyo National Forest as a unit of the National Forest Scenic Area program, under the U.S. Forest Service.
Mill Creek is a 14.5-mile-long (23.3 km) perennial stream that flows east from the Sierra Nevada Mountain Range into Mono Lake, in Mono County, California. It courses through Lundy Canyon and Lundy Lake, before passing through Mono City, California on its way to Mono Lake.
Lee Vining Creek is a 16.2-mile-long (26.1 km) stream in Mono County, California, flowing into the endorheic basin of Mono Lake. It is the second largest stream flowing into the lake, after Rush Creek.
Lake Corcoran is an ancient lake that covered the Central Valley of California.
Lake Russell is a former lake stage of Mono Lake. It was named in honour of Israel Russell, but is also known as Lake Mono in contrast to the present-day lake. This lake was larger than present-day Mono Lake and occasionally overflowed first into the East Walker River and later into the Owens River. During its existence, glaciers from the Sierra Nevada reached until its shore.