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.
© RM 2009. Helicon Publishing is division of RM.