sediment

Any loose material that has ‘settled’ after deposition from suspension in water, ice, or air, generally as the water current or wind speed decreases. Typical sediments are, in order of increasing coarseness: clay, mud, silt, sand, gravel, pebbles, cobbles, and boulders.

Sediments differ from sedimentary rocks, in which deposits are fused together in a solid mass of rock by a process called lithification (solidification). Pebbles are cemented into conglomerates; sands become sandstones; muds become mudstones or shales; peat is transformed into coal.