Sedimentary rocks are formed by small rock pieces which are transported by rivers and laid down in layers. Chalk is a sedimentary rock. Metamorphic rocks are formed when another rock is under heat ...

Igneous rocks form out of cooling lava or magma. Sedimentary rocks develop from eroded grains of other rocks and organic matter. Metamorphic rocks are the third main classification. These started ...

Today, the Denali Fault rips apart some of the North American plate, but it was once a place where tectonic plates came ...