The Antrim, Ellsworth, Bedford, Berea, and Sunbury Formations of Michigan were studied to determine Early Mississippian paleogeography and to develop techniques for studying thick shale sequences with variable properties both laterally and vertically. Variables assessed were color, thickness, lithologic ratio, and texture. Post-Antrim sediments, derived from separate source areas, produced the birdfoot Bedford-Berea delta from the northeast and a thick green shale, the Ellsworth Shale, from the northwest. Localization of rock types on opposite sides of the Michigan basin was not affected by a structural or topographic barrier, but by an environment in which all sedimentsdeposited were primarily or secondarily black. Maps and cross sections delineate rock types.

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