A sedimentary rock that forms when quartz-rich sand along a coast or river or in a desert is buried under layers of more sand and other sediments.

A metamorphic rock characterized by distinct layers of mineral grains (usually micas). Many schists were once shaley sediments that were buried, heated, then put under immense pressure.

One of the three main types of rocks on earth. They form when sediments lithify, or turn into rock.

A sedimentary rock that forms when mud or clay turns to stone.

A layer or series of layers of sediment deposited in a body of still water.