Half Dome, a granite monolith in Yosemite National Park and part of the Sierra Nevada batholith.

A batholith (from Greek bathos, depth + lithos, rock) is a large emplacement of igneous intrusive (also called plutonic) rock that forms from cooled magma deep in the Earth's crust. Batholiths are almost always made mostly of felsic or intermediate rock-types, such as granite, quartz monzonite, or diorite (see also granite dome). Image of Half Dome in Yosemite National Park. ... Image of Half Dome in Yosemite National Park. ... Yosemite National Park (pronounced Yo-SEM-it-ee, IPA: ) is a national park located largely in Mariposa and Tuolumne Counties, California, United States. ... Glacier-sliced Half Dome, Yosemite, a classic granite dome of the Sierra Nevada Batholith The Sierra Nevada Batholith is a large batholith in the Sierra Nevada mountain range, USA, and is a continuous granitic formation that forms much of the Sierra Nevada mountain range of California. ... Igneous rocks are formed when molten rock (magma) cools and solidifies, with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks. ... Pluton redirects here. ... Magma is molten rock located beneath the surface of the Earth (or any other terrestrial planet), and which often collects in a magma chamber. ... Earth cutaway from core to exosphere. ... Felsic is a term used in geology to refer to silicate minerals, magmas, and rocks which are enriched in the lighter elements such as silica, oxygen, aluminium, sodium, and potassium. ... Close-up of granite from Yosemite National Park, valley of the Merced River Quarrying granite for the Mormon Temple, Utah Territory. ... Quartz monzonite is a felsic igneous rock that has an approximately equal proportion of orthoclase and plagioclase feldspars. ... Categories: Mineral stubs | Igneous rocks ... A granite dome is a dome of granite, formed by exfoliation. ...

Although they may appear uniform, batholiths are in fact structures with complex histories and compositions. They are composed of multiple masses, or plutons, bodies of igneous rock of irregular dimensions (typically at least several kilometers) that can be distinguished from adjacent igneous rock by some combination of criteria including age, composition, texture, or mappable structures. Individual plutons are crystallized from magma that traveled toward the surface from a zone of partial melting near the base of the Earth's crust.

Traditionally, these plutons have been considered to form by ascent of relatively buoyant magma in large masses called plutonic diapirs. Because the diapirs are liquefied and very hot, they tend to rise through the surrounding country rock, pushing it aside and partially melting it. Most diapirs do not reach the surface to form volcanoes, but instead slow down, cool and usually solidify 5 to 30 kilometers underground as plutons (hence the use of the word pluton; in reference to the Roman god of the underworld Pluto). It has also been proposed that plutons commonly are formed not by diapiric ascent of large magma diapirs, but rather by aggregation of smaller volumes of magma that ascended as dikes. In physics, buoyancy is the upward force on an object produced by the surrounding fluid (i. ... A lava lamp illustrates the basic principle of diapirism. ... Country rock is a geological term meaning the rock native to an area. ... For other uses, see Volcano (disambiguation). ... Ancient Rome was a civilization that grew from a small agricultural community founded on the Italian Peninsula circa the 9th century BC to a massive empire straddling the Mediterranean Sea. ... Pluto is an alternate name for the Greek god Hades, but was more often used in Roman mythology in their presentation of the god of the underworld. ...

A batholith is formed when many plutons converge together to form a huge expanse of granitic rock. Some batholiths are mammoth, paralleling past and present subduction zones and other heat sources for hundreds of kilometers in continental crust. One such batholith is the Sierra Nevada Batholith, which is a continuous granitic formation that forms much of the Sierra Nevada in California. An even larger batholith, found predominantly in the Coast Mountains of western Canada, extends for 1,800 kilometers and reaches into southeastern Alaska. The Juan de Fuca plate sinks below the North America plate at the Cascadia subduction zone. ... The thickness of the Earths crust (km). ... Glacier-sliced Half Dome, Yosemite, a classic granite dome of the Sierra Nevada Batholith The Sierra Nevada Batholith is a large batholith in the Sierra Nevada mountain range, USA, and is a continuous granitic formation that forms much of the Sierra Nevada mountain range of California. ... This article is about the mountain range in the Western United States. ... Official language(s) English Capital Sacramento Largest city Los Angeles Area  Ranked 3rd  - Total 158,302 sq mi (410,000 km²)  - Width 250 miles (400 km)  - Length 770 miles (1,240 km)  - % water 4. ... The Coast Mountains are the westernmost range of the Pacific Cordillera, running along the south western shore of the North American continent, extending south from the Alaska Panhandle and covering most of coastal British Columbia. ... Official language(s) English[1] Capital Juneau Largest city Anchorage Area  Ranked 1st  - Total 663,267 sq mi (1,717,855 km²)  - Width 808 miles (1,300 km)  - Length 1,479 miles (2,380 km)  - % water 13. ...

There is also an important geographic usage of the term batholith. For a geographer, a batholith is an exposed area of mostly continuous plutonic rock that covers an area larger than 100 square kilometers. Areas smaller than 100 kilometers are called stocks. However, the majority of batholiths visible at the surface (via outcroppings) have areas far greater than 100 square kilometers. These areas are exposed to the surface through the process of erosion accelerated by continental uplift acting over many tens of millions to hundreds of millions of years. This process has removed several tens of kilometers of overlying rock in many areas, exposing the once deeply buried batholiths. Severe soil erosion in a wheat field near Washington State University, USA. For erosion as an operation of Mathematical morphology, see Erosion (morphology) Erosion is displacement of solids (soil, mud, rock and other particles) by the agents of ocean currents, wind, water, or ice by downward or down-slope movement... // Orogeny (Greek for mountain generating) is the process of mountain building, and may be studied as a tectonic structural event, as a geographical event and a chronological event, in that orogenic events cause distinctive structural phenomena and related tectonic activity, affect certain regions of rocks and crust and happen within...

Batholiths exposed at the surface are also subjected to huge pressure differences between their former homes deep in the earth and their new homes at or near the surface. As a result, their crystal structure expands slightly and over time. This manifests itself by a form of mass wasting called exfoliation. This form of erosion causes convex and relatively thin sheets of rock to slough off the exposed surfaces of batholiths (a process accelerated by frost wedging). The result is fairly clean and rounded rock faces. A famous example of the result of this process is Half Dome, which located in the world-famous Yosemite Valley (see picture). Enargite crystals In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ... Mass wasting, also known as mass movement or slope movement, is the geomorphic process by which soil, regolith, and rock move downslope under the force of gravity. ... Geological exfoliation of granite at Enchanted Rock State Natural Area, Texas, USA Exfoliation in geology is a weathering process, mainly caused by freeze-thaw cycles. ... Half Dome is a granite dome at the eastern end of Yosemite Valley, possibly the Valleys most familiar sight. ... Yosemite Valley with Half Dome in the distance. ...

See also

• Granite dome
• Laccolith
• Dike
• Sill
• Volcanic Neck
• Pluton

A granite dome is a dome of granite, formed by exfoliation. ... A laccolith is an igneous intrusion (or concordant pluton) that has been injected between two layers of sedimentary rock. ... A dike in geology refers to a tabular intrusive igneous body. ... In geology, a sill is a tabular, often horizontal mass of igneous rock that has been intruded laterally between older layers of sedimentary rock, beds of volcanic lava or tuff, or even along the direction of foliation in metamorphic rock. ... Volcanic plug near Rhumsiki, Far North Province, Cameroon A volcanic plug, also called a volcanic neck or lava neck, is a volcanic landform created when lava hardens within a vent on an active volcano. ... Devils Tower, an igneous intrusion exposed when the surrounding softer rock eroded away. ...

References

• Plummer, McGeary, Carlson, Physical Geology, Eight Edition (McGraw-Hill: Boston, 1999) pages 61-63 ISBN 0-697-37404-1

• Glazner, Bartley, Coleman, Gray, Taylor, Are plutons assembled over millions of years by amalgamation from small magma chambers?, GSA Today: Vol. 14, No. 4, pp. 4–11

External links

• Idaho Batholith
• The Cornubian Batholith