Devils Tower, an igneous intrusion exposed when the surrounding softer rock eroded away.

In geology, an intrusion is a body of igneous rock that has crystallized from a molten magma below the surface of the Earth. Bodies of magma that solidify underground before they reach the surface of the earth are called plutons, named for Pluto, the Roman god of the underworld. Correspondingly, rocks of this kind are also referred to as igneous plutonic rocks or igneous intrusive rocks. This is to be contrasted with extrusive rocks. The rock surrounding a pluton is called country rock. Devils Tower, Wyoming. ... Devils Tower, Wyoming. ... Devils Tower is a monolith (more technically, an igneous intrusion) located near Hulett and Sundance in eastern Wyoming, above the Belle Fourche River. ... World geologic provinces Oceanic crust  0-20 Ma  20-65 Ma  >65 Ma Geologic provinces  Shield  Platform  Orogen  Basin  Large igneous province  Extended crust Geology (from Greek γη- (ge-, the earth) and λογος (logos, word, reason))[1] is the science and study of the solid matter of a celestial body, its composition... Volcanic rock on North America Plutonic rock on North America Igneous rocks are formed when 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. ... Quartz crystal In chemistry and mineralogy, a crystal is a solid in which the constituent atoms, molecules, or ions are packed in a regularly ordered, repeating pattern extending in all three spatial dimensions. ... Magma is molten rock located beneath the surface of the Earth (or any other rocky planet), and which often collects in a magma chamber. ... Earth (IPA: , often referred to as the Earth, Terra, the World or Planet Earth) is the third planet in the solar system in terms of distance from the Sun, and the fifth largest. ... Pluton redirects here. ... 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. ... Roman mythology, the mythological beliefs of the people of Ancient Rome, can be considered as having two parts. ... // In the study of mythology and religion, the underworld is a generic term approximately equivalent to the lay term afterlife, referring to any place to which newly dead souls go. ... Extrusive refers to a mode of igneous rock formation, in which hot magma from inside the Earth flows out (extrudes) onto the surface. ... Country rock is a geological term meaning the rock native to an area. ...

Varieties

Intrusive rocks include all varieties of igneous rocks from coarse-grained, phaneritic granites of large batholiths to very fine grained, aphanitic, rhyolites in volcanic necks or feeder pipes. In composition, intrusive rocks also include the entire sequence of igneous rock types from the dense and dark ultramafic peridotites to the very light-colored and low-density alkali granites and syenites. A well-known example of an igneous intrusion is Devil's Tower in Wyoming, USA. Quarrying granite for the Mormon Temple, Utah Territory. ... Half Dome A batholith is a large emplacement of igneous intrusive (also called plutonic) rock that forms from cooled magma deep in the Earths crust. ... Rhyolite This page is about a volcanic rock. ... Volcano 1. ... Peridotite Peridotite is a dense, coarse-grained rock, consisting mostly of the minerals olivine and pyroxene. ... Syenite Syenite is a coarse-grained intrusive igneous rock of the same general composition as granite but with the quartz either absent or present in relatively small amounts. ... Devils Tower is a monolith (more technically, an igneous intrusion) located near Hulett and Sundance in eastern Wyoming, above the Belle Fourche River. ... Official language(s) English Capital Cheyenne Largest city Cheyenne Area  Ranked 10th  - Total 97,818 sq mi (253,348 km²)  - Width 280 miles (450 km)  - Length 360 miles (580 km)  - % water 0. ...

Plutonic Sugarloaf Mountain in Rio de Janeiro.

Image File history File links Download high resolution version (2226x1484, 476 KB)This is a personal photo I took on my vacation in Rio. ... Image File history File links Download high resolution version (2226x1484, 476 KB)This is a personal photo I took on my vacation in Rio. ... Sugarloaf as seen from the hilltop neighborhood of Santa Teresa Sugarloaf Mountain (in Portuguese, Pão de Açúcar) is a peak situated in Rio de Janeiro, Brazil, from the mouth of Guanabara Bay on a peninsula that sticks out into the Atlantic Ocean. ... Location of Rio de Janeiro Coordinates: Country Brazil Region Southeast State Rio de Janeiro Mayor Cesar Maia (PFL) Area    - City 1,260 km² Population    - City (2005) 5,613,000 [1]  - Density 4,781/km²  - Metro 11,620,000 [2] Time zone UTC-3 (UTC-3) Website: www. ...

Structural types

Intrusive rocks also exist in a wide range of forms from mountain range sized batholiths to thin vein-like fracture fillings of aplite. Intrusive structures are often classified according to whether or not they are parallel to the bedding planes or foliation of the country rock: if the intrusion is parallel, the body is concordant, while if it cuts across the country rock, it is discordant. Structural types include: Aplite is a fine to very fine-grained sugary-textured rock of granite composition. ... In mathematics, a foliation is a geometric device used to study manifolds. ...

• batholith: large irregular intrusions.
• stock: smaller irregular discordant intrusions.
• dike: a relatively narrow tabular discordant body, often with near-vertical attitude.
• sill: a relatively thin tabular concordant body intruded along bedding planes, often near-horizontal when emplaced, but may be intruded into tilted beds or the entire package may be tilted by later deformation.
• pipe or volcanic neck: circular or tube shaped nearly vertical body which may have been a feeder vent for a volcano.
• laccolith: concordant body with essentially flat base and dome shaped upper surface, usually has a feeder pipe below.
• lopolith: concordant body with a relatively flat to sagging top and a shallow covex base (spoon-shaped), may have a feeder dike or pipe below.
• phacolith: a concordant lense shaped pluton that typically occupies the crest of an anticline or the trough of a syncline.

Half Dome A batholith is a large emplacement of igneous intrusive (also called plutonic) rock that forms from cooled magma deep in the Earths crust. ... 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. ... This article is about volcanoes in geology. ... A laccolith is an igneous intrusion (or concordant pluton) that has been injected between two layers of sedimentary rock. ... A phacolith is a pluton parallel to the bedding plane or foliation of folded country rock. ... Anticline with syncline visible at far right- USGS In structural geology, an anticline is a Fold (geology) that is convex to the youngest beds—youngest sediments are on back of hand, older under the palm. ... In geology, a syncline is a type of fold that involves an upward slope to either side. ...

See also

• Diapir
• Mud volcano
• Pluton
• Ultramafic intrusion