When rocks break down they turn into smaller pieces of rocks and minerals. Weathering or erosion causes this. Wind erosion is when a rock is almost always in the wind and is slowly being ground away. Weathering is mostly a chemical reaction, helped by water.

The rock particles are called sediment. Sediment is eventually carried to a new lower place, often riverbeds or oceans. The sediments are separated into layers and become buried and compacted. Eventually the particles are cemented together and are known as sedimentary rocks.

Some examples of sedimentary rocks are breccia, pudding stone, shale, and limestone.