Rocks

Types of Rocks

• There are three main types of rocks; igneous, sedimentary, and metamorphic.
• Crystallization, erosion and sedimentation, and metamorphism transform one type of rock into another type of rock or change sediments into rock.
• The rock cycle describes the transformations of one type of rock to another.

Igneous Rocks

• Igneous rocks form either when they cool very slowly deep within the Earth or when magma cools rapidly at the Earth's surface.
• Composition of the magma will determine the minerals that will crystallize forming different types of igneous rocks.

Sedimentary Rocks

• Weathering and erosion produce sediments. Once these sediments are deposited, they can become sedimentary rocks.
• Sediments must be compacted and cemented to make sedimentary rock. This process is called lithification.

Metamorphic Rocks

• Metamorphic rocks form when heat and pressure transform an existing rock into a new rock.
• Contact metamorphism occurs when hot magma transforms rock that it contacts.
• Regional metamorphism transforms large areas of existing rocks under the tremendous heat and pressure created by tectonic forces.