Sedimentary rocks are formed by erosion. Sediments are moved from one place to another. Sediments are deposited in layers, with the older ones on the bottom. The layers become compacted and cemented together to form rocks. Sedimentary Rocks are formed at or near the Earth’s surface. There are two types of Sedimentary Rocks; Clastic Rocks: made of fragments of rock cemented together e.g. Breccia. And Non-Clastic: Minerals crystallize out of solution to become rock e.g. limestone. Or are formed from remains of plants and animals; e.g. coal.