Sedimentary rocks are made up of sediments.why?
Answers
Clastics are broken rocks. Clastic rocks are formed from fragments of other rocks. The common sedimentary rocks formed either in deep basins or from sand dunes are not normally considered clastics due to the small grain size.
In the western U.S. we have braided-stream deposits washing down from bare rock. Those contain a mixture of grain sizes from clay to boulders and in shapes from sharp and broken to round cobbles. Such deposits can become cemented by groundwater minerals and look much like a piece of broken concrete with exposed sand and gravel of different sizes.
There are fault clastics, also called fault breccia. Whether the native rock was igneous, sedimentary or metamorphic, the fractured-to-powdered rock in the fault can be re-cemented by minerals in groundwater. On inspection, that rock appears sedimentary but is considered to be the same category as the native rock.
Explanation:
Sedimentary rocks are formed when sediment is deposited out of air, ice, wind, gravity, or water flows carrying the particles in suspension. This sedimentis often formed when weathering and erosion break down a rock into loose material in a source area.