The Michigan basin, an almost circular and symmetrical structural basin, contains in the deepest part approximately 14,000 ft of Paleozoic sedimentary rocks. The autogeosyncline developed as a tectonic element in Late Silurian time, during which the middle third of the sedimentary section was deposited. The strata dip generally less than 1° toward the center of the basin, although locally there are gentle open folds and a few high-angle faults. The sedimentary formations can be classified into four generalized sequences--(1) the sandstone sequence of the Cambrian, (2) the carbonate-evaporite sequence of the Ordovician to Middle Devonian, (3) the shale-sandstone sequence of the Late Devonian to Mississippian, and (4) the coal-bearing sequence of the Pennsylvanian.

The Cambrian sandstones (Mount Simon) have the most favorable properties for high-volume liquid-waste disposal. They are suitably thick and reasonably shallow principally in southeastern Michigan near Detroit. The Mount Simon is a typical blanket feldspathic, quartzose sandstone; it is characterized by quartz and feldspar cement, present as grain overgrowths, and detrital and matrix carbonate minerals. Where measured, the porosity averages about 10 percent and the permeability about 30 md. The Cambrian sandstone beds are overlain by a thick, extensive shale layer (Utica) and salt beds (Salina), which are of secondary importance to liquid- and solid-waste disposal.