Index map
A giant incomplete bulls-eye is centered on the state of Michigan. Extending into Illinois, Ohio, Indiana, Wisconsin, and Ontario, this annular pattern outlines the Michigan Basin, a bowl-shaped structure of uncertain origin that contains over 4 km of inward-dipping Paleozoic strata and a veneer of Jurassic sedimentary rocks. This mysterious basin is located in the tectonically less active interior of the continent, between the Appalachians and the Rocky Mountains. It subsided rapidly from Cambrian to Silurian time as it filled with shallow-water marine sediments, some of which host deposits of petroleum, coal, and salt. |
