Sedimentary rocks are layered. Some form when particles of rocks and minerals settle out of water or air. Others form when minerals precipitate directly out of water. Sedimentary rocks are identified by their minerals and texture.
As the sediments pile up, water is driven out by the weight of the overlying pile, and minerals precipitate around the sediment particles, cementing them into rock. This process is called lithification.
Limestone is one of the most widespread sedimentary rocks.
Shale is made up clay and silt, particles that are finer than sand.
Sandstone is made of sand, which accumulates in rivers and along ocean shores where water moves fast enough to remove the finer particles.