Rocks What is a rock? a. Naturally occurring b. Solid Made of two or more minerals. Composed mostly of these eight elements: Oxygen-O; Silicon-Si; Aluminum-Al; Iron-Fe; Calcium-Ca; Sodium-Na; Potassium-K; Magnesium-Mg d. Their classification is based on how they were formed.

Rock Types by Formation a. Igneous Temperatures in lower crust and upper mantle melt rock into magma. Approximately 1400 degrees C. This liquid is less dense than solid rock so it rises. As the magma rises, magma cools and hardens to form igneous rocks.

Rock Types by Formation b. Sedimentary (most common) Sediments, small pieces of rock, shells and other organic material are carried by wind or water and deposited. As layers of sediment deposit on top of each other they are compacted and cemented into sedimentary rock.

Rock Types by Formation c. Metamorphic a result of changes that occur to existing rocks. Changes are caused by high heat, pressure, or by chemical reactions.

The rock cycle shows how the three rock types relate to each other.

weathering, crystallization, metamorphism Rock Cycle There are 4 processes of rock formation that are the links between the rock types, sediment and magma. weathering, crystallization, lithification metamorphism

Weathering is the gradual wearing down of all rock types once they are exposed at the surface.

is the cooling of magma to form an igneous rock. Crystallization is the cooling of magma to form an igneous rock.

Lithification is the transformation of loose sediment into a rock by a slight heating and/or cementation.

Metamorphism occurs when a rock is subjected to heat and pressure, transforming a rock. This can occur on any rock, even a metamorphic rock.