GEOL 1601 Chapter : Sedimentary Rocks Are Formed By The Accumulation Of Sediments
Document Summary
Sedimentary rocks are formed by the accumulation of sediments. There are three basic types of sedimentary rocks. Clastic sedimentary rocks such as breccia, conglomerate, sandstone, siltstone, and shale are formed from mechanical weathering debris. Chemical sedimentary rocks, such as rock salt, iron ore, chert, flint, some dolomites, and some limestones, form when dissolved materials precipitate from solution. Organic sedimentary rocks such as coal, some dolomites, and some limestones, form from the accumulation of plant or animal debris. Photos and brief descriptions of some common sedimentary rock types are shown on this page. Coal is an organic sedimentary rock that forms mainly from plant debris. The plant debris usually accumulates in a swamp environment. Coal is combustible and is often mined for use as a fuel. Chert is a microcrystalline or cryptocrystalline sedimentary rock material composed of silicon dioxide (sio2). It occurs as nodules and concretionary masses, and less frequently as a layered deposit.
