Shale is a sedimentary rock with complex compositions, but all of them have thin-shale or lamellar joints. It is mainly composed of clay deposited by pressure and temperature, but mixed with quartz, feldspar clastic and other chemical substances. Tiny particles of shale formed by hardening clay materials are easily broken up and are easily divided into obvious rock formations. Clay rock. The composition is complex. Besides clay minerals, there are also many detrital minerals and authigenic minerals. Having a sheet or lamellar bedding. It is easy to split into pieces with hard objects. It is formed by compaction, dehydration and recrystallization of clay materials. Shale is weak in weathering resistance, and it often causes erosion and low mountains and valleys on the terrain. Shale is impervious to water and often becomes an aquifer in the distribution of groundwater.