laccolith

[lak-uh-lith]
noun Geology.
a mass of igneous rock formed from magma that did not find its way to the surface but spread laterally into a lenticular body, forcing overlying strata to bulge upward.
Also, laccolite [lak-uh-lahyt] .


Origin:
1875–80; < Greek lákko(s) pond + -lith

laccolithic, laccolitic [lak-uh-lit-ik] , adjective
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World English Dictionary
laccolith or laccolite (ˈlækəlɪθ, ˈlækəˌlaɪt)
 
n
See lopolith a dome-shaped body of igneous rock between two layers of older sedimentary rock: formed by the intrusion of magma, forcing the overlying strata into the shape of a dome
 
[C19: from Greek lakkos cistern + -lith]
 
laccolite or laccolite
 
n
 
[C19: from Greek lakkos cistern + -lith]
 
lacco'lithic or laccolite
 
adj
 
laccolitic or laccolite
 
adj

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American Heritage
Science Dictionary
laccolith   (lāk'ə-lĭth')  Pronunciation Key 
A body of igneous rock intruded between layers of sedimentary rock, resulting in uplift. Laccoliths are usually plano-convex in cross-section, having a flat bottom and a convex top, and are roughly circular in plan. They are usually connected to a dike and are typically up to 8 km (5 mi) in diameter and tens to hundreds of meters thick. See illustration at batholith.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Encyclopedia Britannica
Encyclopedia

laccolith

in geology, any of a type of igneous intrusion that has split apart two strata, resulting in a domelike structure; the floor of the structure is usually horizontal. A laccolith is often smaller than a stock, which is another type of igneous intrusion, and usually is less than 16 km (10 miles) in diameter; the thickness of laccoliths ranges from hundreds of metres to a few thousand metres. They can be contrasted with sills, which are sheetlike intrusions oriented parallel to the bedding of the enclosing rock: a laccolith's ratio of diameter to thickness should be less than 10; a larger ratio would make the body a sill. Acidic rocks are more common than basic rocks in laccoliths. Although the lower portions of laccoliths are seldom visible, they usually are interpreted as having a relatively small feeder from a magma source below. A well-known example of a laccolith is found in the Henry Mountains, Utah.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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Example sentences
The hardened magma that forms this type of dome is called laccolith.
The range is an exposed laccolith, but the lake is in the area of uplifted sedimentary rocks rather than exposed igneous rocks.
At the extreme right the sedimentary rocks are upturned on the flanks of the laccolith.
Related Words
Image for Laccolith
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