Sediment is solid material that is moved and deposited in a new location. Sediment can consist of rocks and minerals, as well as the remains of plants and animals. It can be as small as a grain of sand or as large as a boulder.
Sediment moves from one place to another through the process of erosion. Erosion is the removal and transportation of rock or soil. Erosion can move sediment through water, ice, or wind.

Water can wash sediment, such as gravel or pebbles, down from a creek, into a river, and eventually to that river’s delta. Deltas, river banks, and the bottom of waterfalls are common areas where sediment accumulates.