The Sierra Nevada Batholith is a large

batholith A batholith () is a large mass of intrusive igneous rock (also called plutonic rock), larger than in area, that forms from cooled magma deep in Earth's crust. Batholiths are almost always made mostly of felsic or intermediate rock types, such ...

which forms the core of 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 ...

mountain range in

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 ...

, exposed at the surface as

granite Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergro ...

. The batholith is composed of many individual masses of rock called ''

plutons In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and com ...

'', which formed deep underground during separate episodes of

magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural sa ...

intrusion In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and com ...

, millions of years before the Sierra itself first began to rise. The extremely hot, relatively

buoyant Buoyancy (), or upthrust, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus the pr ...

plutons, also called ''plutonic

diapirs A diapir (; , ) is a type of igneous intrusion in which a more mobile and ductily deformable material is forced into brittle overlying rocks. Depending on the tectonic environment, diapirs can range from idealized mushroom-shaped Rayleigh–T ...

'', intruded through denser, native

country rock Country rock is a genre of music which fuses rock and country. It was developed by rock musicians who began to record country-flavored records in the late 1960s and early 1970s. These musicians recorded rock records using country themes, vocal s ...

and sediments, never reaching the surface. At the same time, some magma managed to reach the surface as volcanic lava flows, but most of it cooled and hardened below the surface and remained buried for millions of years. The batholith – the combined mass of subsurface plutons – became exposed as

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 k ...

forces initiated the formation of the

Basin and Range Basin and range topography is characterized by alternating parallel mountain ranges and valleys. It is a result of crustal extension due to mantle upwelling, gravitational collapse, crustal thickening, or relaxation of confining stresses. The e ...

geologic province, including the Sierra Nevada. As the mountains rose, the forces of

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distin ...

eventually wore down the material which had covered the batholith for millions of years. The exposed portions of the batholith became the granite peaks of the High Sierra, including

Mount Whitney Mount Whitney (Paiute: Tumanguya; ''Too-man-i-goo-yah'') is the highest mountain in the contiguous United States and the Sierra Nevada, with an elevation of . It is in East–Central California, on the boundary between California's Inyo and Tu ...

Half Dome Half Dome is a granite dome at the eastern end of Yosemite Valley in Yosemite National Park, California. It is a well-known rock formation in the park, named for its distinct shape. One side is a sheer face while the other three sides are smoo ...

and

El Capitan El Capitan ( es, El Capitán; "the Captain" or "the Chief") is a vertical Rock formations in the United States, rock formation in Yosemite National Park, on the north side of Yosemite Valley, near its western end. The El Capitan Granite, granit ...

. Most of the batholith, however, remains below the surface.

Origins

The Sierra batholith was formed when the

Farallon Plate The Farallon Plate was an ancient oceanic plate. It formed one of the three main plates of Panthalassa, alongside the Phoenix Plate and Izanagi Plate, which were connected by a triple junction. The Farallon Plate began subducting under the west ...

subducted Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the ...

below 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 Pacific ...

. The resultant molten rock rose through the Earth's crust over the span of 100 Ma, forming several

pluton In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and com ...

s, or a chain of volcanoes if the

reached the surface. Most of the granitic rocks formed between 105 and 85 Ma, during the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

, with pluton formation ending around about 70 Ma.

Erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distin ...

from 85 until 15 Ma removed the volcanic rocks and exposed the granitic core.

Reference

External links

* * {{Authority control Sierra Nevada (United States) Batholiths of North America Igneous petrology of California Mesozoic magmatism

Origins

See also

Reference

External links