page_title: Bedford Shale
section_title: Michigan
hierarchical_section_title: Bedford Shale / Geographic Extent / Michigan
caption_attribution_description: English: Portion of global paleogeographic reconstruction of the Earth in the middle Devonian period 385 million years ago, showing Eastern North America with key features labeled
context_page_description: The Bedford Shale is a shale geologic formation in the states of Ohio, Michigan, Pennsylvania, Kentucky, West Virginia, and Virginia in the United States.
context_section_description: In Michigan, the Bedford Shale is found in the southeast along shores of Lake Erie and Lake St. Clair; along the shore of Lake Huron north of Saginaw Bay; along the south shore of the Straits of Mackinac; north of 44 degrees latitude along the shore of Lake Michigan; and in the far southwest corner of the state. The Bedford Shale was first identified in Michigan in 1876 in the southeastern part of the state. Some sources say the shale is 50 to 100 feet (15 to 30 m) thick while others say it is generally about 60 feet (18 m) thick. It is almost 250 feet (76 m) thick in The Thumb of Michigan, and about 65 feet (20 m) thick in Southeast Michigan. The Bedford Shale becomes finer-grained and thins from Lake Erie/Lake St. Clair to the west, pinching out to extinction near the center of the Michigan Basin and merging with the upper part of the Ellsworth Shale. In south-central Michigan, the Bedford Shale grades into and intertongues with the Antrim Shale.
  There are no known outcrops of the Bedford Shale in Michigan, as it and the rocks above it are covered by Pleistocene glacial drift.
caption: Eastern North America in the Middle Devonian, showing the Michigan Basin of the Rheic Ocean.
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