Clastic rocks are sedimentary rocks composed of fragments, or clasts, of pre-existing minerals and rocks. These fragments are transported by water, wind, or ice and deposited in different environments, where they are lithified into rock. Clastic rocks, such as sandstone, shale, and conglomerate, are key in reconstructing past environments and understanding sedimentary processes.
Source Boggs, S. (2009). Petrology of Sedimentary Rocks. Cambridge University Press.