The Michigan basin is a relatively simple, circular basin, up to 17,000 feet deep, centered in the Lower Peninsula of Michigan. The stratigraphic section consists primarily of clastic and carbonate rocks of Cambrian to Pennsylvanian age. Petroleum production from the Michigan basin dates back to 1885, and, as of 1984, cumulative production totaled over 958 million barrels of oil and almost 2.3 trillion cubic feet of natural gas. The discovered fields and remaining prospects can be divided into eight plays for purposes of description and assessment: (1) the Mississippian-Pennsylvanian gas play, (2) the Antrim Shale play, (3) the Devonian anticlinal play, (4) the Niagaran reef play, (5) the Trenton-Black River play, (6) the Prairie du Chien play, (7) the Cambrian play, and (8) the Precambrian rift play.