what are sedimentary rocks

Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. They are one of the three main types of rocks, along with igneous and metamorphic rocks. Sedimentary rocks can be formed from the compression of ocean sediments, deposits that accumulate on the Earth's surface, or the solidification of preexisting unconsolidated sediments. They are often laid down in layers called beds or strata and contain important information about the history of the Earth, including fossils and clues about the original rock. There are three main groups of sedimentary rocks: clastic, biologic, and chemical