Sedimentary Rocks
Sedimentary rocks are made out of sediment and/or a chemical reaction. Sediment is a mixture of dead plants, animals, rocks, sand and minerals. Sediment is washed downstream where it settles to the bottom of rivers, lakes, and oceans. The first layer of sediment is deposited and then other layers keep coming to form more layers. Layers and layers of sediment gather until the weight of each layer forms a rock. This is called compaction. Minerals in some rocks dissolve as water soaks in. Minerals that dissolve form a natural cement and then sticks the larger pieces of sediment. This is called cementation.