Clastic rock
A sedimentary rock made of fragments of preexisting rocks or minerals that have been transported, deposited, and lithified.
Sediment: Loose mineral grains, rock fragments, or organic material transported and deposited by natural processes. Clastic rocks begin as sediment before burial and lithification.
Weathering: The breakdown or alteration of rock at or near Earth's surface. Weathering supplies fragments that can become clastic sediment.
Conglomerate: A clastic sedimentary rock containing rounded gravel-sized clasts. Its rounded coarse fragments record transport before lithification.
Chemical sedimentary rock: A sedimentary rock formed when dissolved substances precipitate from water. It forms from precipitated material rather than transported rock fragments.
Grain size: A measure of the diameter of particles in a sediment or rock. Grain size separates clastic rocks into categories such as conglomerate, sandstone, and shale.
Erosion: The removal and transport of weathered material by water, wind, ice, or gravity. Erosion moves source-rock fragments toward sites of sediment deposition.
Breccia: A clastic sedimentary rock containing angular gravel-sized clasts. Its angular fragments contrast with the rounded clasts of conglomerate.
Biochemical sedimentary rock: A sedimentary rock formed from accumulated biological material or mineral remains produced by organisms. Its particles derive chiefly from organisms, unlike clasts eroded from older rocks.
Sorting: The degree to which sediment particles have similar sizes. Sorting records how transport and deposition selected grains in clastic rocks.
Sediment transport: The movement of sediment by flowing water, wind, ice, or gravity. Transport sorts and rounds the particles that later form clastic rock.