The three types of rocks
IgneousIgneous rock forms from the cooling of magma or lava. Extrusive igneous rocks are formed from the lava flowing out of a volcano and make rocks like pumice. Intrusive igneous rocks are from magma slowly cooled inside the earth's crust and include rocks like granite.
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SedementarySedimentary rocks occur when particles layer together and compact with organic matter then cement together. This process can occur near or on the surface and can occur underwater. Sandstone and limestone are two prime examples of sedimentary rocks.
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MetamorphicMetamorphic rock occurs when any rock type, including other metamorphic rocks, are subjected to different heat and pressure. This process happens deep within the Earth's crust under higher temperatures and pressures. Metamorphic rocks account for about 27% of the rocks in the crust.
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