Rocks and the Rock Cycle
Layers of rocks can be faulted, folded and tilted by large forces within the Earth's crust. The study of these changes can give information about the strength and direction of the forces involved.
Sedimentary rocks - layers of rock fragments that were compressed and cemented together. They often contain fossils.
Igneous rocks - molten rock that cools and solidifies. They do not contain fossils.
Metamorphic rocks - existing rocks that are compressed and heated without melting. They have the same chemical composition as the rocks from which they were made.