Sedimentary rocks are either made up of broken and eroded fragments of pre-existing rocks that have been transported to their site of deposition by the action of water, ice, wind or gravity (e.g. sandstone and mudstone) or formed by the accumulation of the remains or secretions of animals and plants (e.g. fossiliferous limestone and coal) or by the precipitation of minerals from solution (salt and other evaporite deposits). These three processes have resulted in the formation of detrital, biological and chemical sedimentary rocks, respectively.