Rocks, like many things in this world, move in cycles. Although we don't think of rocks as changing, they do. All rocks on Earth are a part of a large process called the rock cycle. In this cycle, rocks are created and changed by different processes. There are three types of rocks: Igneous rocks, Sedimentary, and Metamorphic. Sedimentary rocks are rocks formed from materials, not hooked together, which were created from weathering and erosion of pre-existing rocks. Weathering is a process of breakdown of rocks at the Earth's surface by the action of wind, rain, and ice. Sedimentary Rocks are nothing more then a sediment cemented together to form a rock. Many times you can find these rocks at the beach, where bits of seashells have been stuck together to form a rock. Sedimentry rocks can be changed into metamorphic rocks. The change occurs when sedimentary rocks are exposed to extreme heat and pressure. The heat and pressure change the structure of the rock and make it metamorphic. This process can also happen with igneous rocks. Liquid (molten) rock material solidifies at depth or at the earth's surface to form igneous rocks. Igneous rocks are formed when molten material like magma or lava and cools and solidifies. Magma is molten silicate material generated by melting deep withing the Earth.

High temperatures are generated by radioactive decay and pressure is provided by the overlying pile of rock. The alteration is caused by heat, pressure, or chemically active fluids (also known as diagenisis.) These rocks are altered, but not melted.

This is the basic cycle that rocks go through. The graphic representing the rock cycle is intended to show the interrelationships among rocks and the roles of various geologic processes in transforming one rock type into another.

Metamorphic rocks are rocks formed by the alteration of pre-existing rocks deep within the Earth. Metamorphism is the deep subsurface process by which sedimentary (and igneous) rocks are changed by the action of temperature, pressure and fluids. New minerals grow and a metamorphic rock is the product of the change. When metamorphic rock is exposed to the extreme heat of Earth's interior it melts and creates magma. Uplift and exposure of rocks at the Earth's surface destabilizes these mineral structures. The minerals break down into smaller grains which are transported and deposited (either from solution or by lowering the hydraulic energy regime) as sediments. As the magma cools either inside the earth or when it comes to the surface it forms igneous rocks. This process is called crystalization and can occur above or below the Earth's surface. These igneous rocks then erode and deposit sediment which can later become sedimentary rock.

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