GLG 101 Igneous Rocks Checkpoint

GLG 101 Igneous Rocks Checkpoint - intrusive igneous rock...

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Igneous Rocks Checkpoint An igneous rock is from the three main rock groups and is formed from the cooling of lava or magma. Igneous rocks originate from the magma that flows out of a volcano onto the Earth’s surface which then becomes lava. The magma that does not make it to the surface also forms an igneous rock. Two types or categories of igneous rock are extrusive and intrusive. Extrusive igneous rock is formed outside the Earth’s core, whereas intrusive igneous rock is formed within the Earth’s surface. An extrusive rock that is formed at the crust of the Earth’s surface becomes solid and cools quicker than the intrusive rock. Therefore, extrusive rock is typically fine grained. The
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Unformatted text preview: intrusive igneous rock cools very slowly and is formed within the crust of the Earth. An intrusive rock can be identified by its size and shape whereas the extrusive rocks need to be examined through a microscope to be properly identified. Typical types of intrusive rock include batholiths, stocks, laccoliths, sills and dikes. Intrusive and extrusive rock forms various types of everyday features when they are cooled. For example, granite is a popular version of intrusive rock. One can also find intrusive rock at your local cemetery because that is what the headstones are made out of. Extrusive rock can be found in the form of pumice, basalt and obsidian glass....
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This note was uploaded on 01/30/2011 for the course GLG 101 taught by Professor Brewer during the Fall '10 term at University of Phoenix.

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