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Deposition is the process by which wind or water sediment settles out in layers. Furthermore, over time, the remains of living things may harden in this sediment and change into fossils. After sediment is deposited the processes of compaction and cementation change the fragments into sedimentary rock. Compaction. At first, the fragments of rock lie loosely together. But gradually, over many, many years these thick layers build up. This build up becomes heavy and presses down on the layers beneath it. Compaction is the pressing down of layers forcing the sediments to fit closer together. Over millions of years, this process can squeeze fragments tightly together. The layers often remain visible in the rock and may be used to identify sedimentary rock. Cementation
Weathering breaks down the mountainâs surface into tiny pieces called sediment. Over time, the forces of weathering (wind, water, rain, ice, waves, chemicals, gravity, and organisms) wear down and eventually level the mountain by breaking up or dissolving its rock into smaller and smaller pieces. The next step in the process is erosion. Erosion is the carrying away, movement, or removal of weathered rock, dirt, and other bits of earth from one place to another by wind and water in various forms. One of the more forceful agents of erosion is running water, which picks up and transports weathered material.