The Devonian shales of the eastern United States are a potential source for tremendous volumes of liquid and gaseous hydrocarbons. The Antrim Shale of Michigan is a part of this extensive body of rock. As part of the Shale Characterization Program, stratigraphic cross sections showing the Antrim Shale and associated formations have been constructed for various parts of the Michigan Basin. The principal formations include the Antrim Shale of Devonian age, the Ellsworth Shale which correlates primarily with the Antrim Shale but whose uppermost part appears to correlate with parts of certain formations of Mississippian age, and the Bedford Shale, Berea Sandstone and Sunbury Shale of eastern Michigan. The Bedford Shale immediately overlies the Antrim in eastern Michigan. Regional cross sections are constructed from gamma ray logs as illustration of the stratigraphic associations of these Devonian and Mississippian formations in the Michigan Basin. Data from gamma ray logs and records of 99 individual wells distributed throughout the Southern Peninsula of Michigan were used to construct six cross sections, and a network of intersecting cross sections which illustrates depths, thicknesses, and the stratigraphic relationship of the subject formations in various sectors of the Basin.