Research topic: shale

shale sedimentary rock formed by the consolidation of mud or clay, having the property of splitting into thin layers parallel to its bedding planes. Shale tends to be fissile, i.e., it tends to split along planar surfaces between the layers of stratified rock. Shales comprise an estimated 55% of all sedimentary rocks. The composition of shale varies widely. Shales with very high silica content may have been formed when large quantities of diatoms and volcanic ash were present in the original sediment. Large numbers of fossils in shales may give them a high calcium content; such shales... Read more