By: Christina Mathew

What is a Rock?

Rocks are composed of minerals. They are classified by how they were formed (their origin).There are three types of rocks: Igneous,Metamorphic and Sedimentary.

Examples of Igneous, Sedimentary and Metamorphic Rocks

Rock Cycle

The rock cycle is a model showing how rocks and sediments change overtime. External processes occur on earth's surface. An example is weathering and erosion. Internal processes occur within the earth. An example is any process that requires exposure to extreme heat and/or pressure.
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