Types of Rocks

Posted by on Monday, July 25, 2016

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The three main types, or classes, of rock are sedimentary, metamorphic, and igneous and the differences among them have to do with how they are formed.

Sedimentary rocks are types of rock that are formed by the deposition and subsequent cementation of that material at the Earth's surface and within bodies of water.

A metamorphic rock is a result of a transformation of a pre-existing rock. The original rock is subjected to very high heat and pressure, which cause obvious physical and/or chemical changes. 

Igneous rocks form when the magma or molten rock pours out onto the earth's surface or erupts at the earth's surface from a volcano . Extrusive rocks are also called volcanic rocks. 



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