How was the Marcellus Shale formed?
Shale is rock formed from very fine grained to clay-like sediments that have been compressed over time. The Marcellus Shale is the basal unit of the Devonian Hamilton Group, which is famous in New York state for beautiful fossil preservation of marine organisms. The reason that the Marcellus Shale is rich in natural gas is because, when the shale was deposited as a mud, it was full of tiny pieces of organic material. The same heat and pressure that turned the mud into shale also ‘cooked’ the organic material, creating natural gas.
