Rocks and the Rock Cycle Igneous, Sedimentary, Metamorphic

The Rock Cycle As you may recall the rock cycle is the changing of rocks from one kind to another over long periods of time. But what are these igneous, sedimentary, and metamorphic rocks anyway?

Igneous Rocks Extrusive – rocks formed from lava exposed to the Earth’s surface (example: basalt) Extrusive rock cools quickly

Igneous Rocks Intrusive – rocks formed deep within the Earth (example: granite) Intrusive rock cools slowly

Sedimentary Rocks Clastic – rocks made from fragments of previously existing rock (example: conglomerate)

Organic – rocks made from material that was once living (example: limestone, coal) Sedimentary Rocks

Chemical – rocks made when a sea or lake dries up leaving large amounts of minerals to be deposited (example: gypsum, rocksalt) Sedimentary Rocks

Metamorphic Rocks Foliated – rocks with parallel layers or bands (example: slate, schist, gneiss)

Unfoliated – rocks not banded into layers (example: marble, quartzite) Metamorphic Rocks