Each type of sedimentary rock matched with its composition;
1. Clastic - Weathered rock particles
2. Organic - Dead creatures
3. Chemical - Mineral crystals
Clastic sedimentary rocks are rocks that are formed from fragments (clasts) of pre-existing rocks. The rock particles that constitute clastic rocks are broken down by weathering processes due to their exposure to weathering agents such as water and wind. Examples are shale, breccia and sandstone.
Organic sedimentary rocks are rocks that are composed of accumulated decayed remains of organisms (plants and animals). Examples are coal and oil shale.
Chemical sedimentary rocks are rocks that are composed of mineral crystals. They form as sediments when mineral constituents settles down in a solution. Examples are halite and gypsum.