How are sediment and sedimentary rock formed?
Sediment forms at Earth’s surface by weathering in place forming residual soil but most often it is transported by a moving fluid such as stream water to eventually be deposited as layers in shallow marine environment. For example, large amounts of sand and gravel accumulate at shorelines while finer silt and clay are deposited in shallow water and limy mud and shells in reef environments. As sediments are buried by successively younger sediment layers, they are transformed to rock layers by pressure, drying, and cementation to form the sedimentary rocks, gravelly sandstone, shale, and limestone respectively. Sedimentary rocks contain features that reveal Earth history and fossils that preserve a record of over three billion years of life.
