The surface of the Earth is constantly changing. This relentless march of sediments to the sea determines the temporary nature of water storage dams, which will eventually fill with sediments and become useless as reservoirs.
Sediments are earth materials that are deposited in particulate, unconsolidated form.
Sand and mud are examples of sediments. The most abundant sediments come from the weathering and chemical breakdown of continental rocks. Buried with the sediments are skeletons of the animals that lived during that time. For example, older particles will be more rounded due to weathering. Because certain kinds of animals and plants lived only during certain time periods, the types of fossils found in sediments allow scientists to determine the approximate date at which they were deposited.