How do the three types of sedimentary rocks form?
Clastic: your basic sedimentary rock. Clastic sedimentary rocks are accumulations of clasts: little pieces of broken up rock which have piled up and been “lithified” by compaction and cementation. Chemical: many of these form when standing water evaporates, leaving dissolved minerals behind. These are very common in arid lands, where seasonal “playa lakes” occur in closed depressions. Thick deposits of salt and gypsum can form due to repeated flooding and evaporation over long periods of time. Organic: any accumulation of sedimentary debris caused by organic processes. Many animals use calcium for shells, bones, and teeth. These bits of calcium can pile up on the seafloor and accumulate into a thick enough layer to form an “organic” sedimentary rock. http://jersey.uoregon.edu/~mstrick/geolo… if you want more info.
