Percy has found a clastic sedimentary rock.
Clastic sedimentary rocks are rocks that are composed of pebbles, rock or sand particles of pre-existing rocks. These type of rocks are formed by weathering processes when pre-existing rocks are exposed to water, wind or ice. The rocks are broken down and moved to some basin where they become trapped and become compacted and cemented to form sedimentary rocks. Clastic sedimentary rocks are classified based on the grain size of the sediment and the types of rock particles that constitute the sediment. They include; conglomerate, shale, breccia and sandstone.