Sedimentary rocks form through the compaction and cementation of sediments. There are three main types: clastic rocks like shale and sandstone form from fragments of pre-existing rocks; chemical rocks like rock salt form through precipitation from solution; and organic rocks like coal form from the remains of plants and animals. Clastic rocks specifically form through the weathering of parent rocks, transportation of fragments by wind/water, deposition, and cementation as minerals fill the spaces between fragments.