The Rock Cycle

The rock cycle has only three types of rocks, igneous rock, sedimentary rock and metamorphic rock. Each of these rocks can form at the expense of the other. Igneous rocks are created when molten material such as magma (within the earth) or lava (on the surface) cools and hardens. The hot material crystallizes into different materials. The properties and sizes of the various crystals depend on the magmas composition and its rate of cooling. Examples of Igneous rock are Granite, Obsidian, Basalt, Pumice, Andesite, Diorite and Rhyolite. Sedimentary rocks are made up of sediments eroded from igneous rock, metaphoric rock, other sedimentary rocks, and even the remains of dead plants and animals. These materials are deposited in layers, or strata, and then are squeezed and compressed into rock. Most fossils are found in sedimentary ro...