• journal_title：Geology
• Contributor：R. David Matthews
• Publisher：Geological Society of America
• Date：1983-
• Format：text/html
• Language：en
• Identifier：10.1130/0091-7613(1983)11<327:FFTASD>2.0.CO;2
• journal_abbrev：Geology
• issn：0091-7613
• volume：11
• issue：6
• firstpage：327

The inconspicuous fossil Foerstia marks a time zone within the black shale sequences of Late Devonian age of the eastern United States. It is best known from locations in Ohio, but it has been reported from Ontario to Tennessee and provides a basis for stratigraphic correlation between the Illinois and Appalachian Basins. The discovery of Foerstia in Michigan aids correlation of Michigan Basin sequences to those of the Appalachian and Illinois Basins. A cored zone some 1.5 m thick contains several foerstian remains within Unit 2 in a well located in eastern Michigan. Unit 2 correlates with the Middle Huron Member of the Ohio Shale, and Units 1A, 1B, and 1C in the Antrim correlate with the Lower Huron. Units 3, 4, and 5 and 6 correspond, respectively, to the Upper Huron, Chagrin, and Cleveland. Unit 4 may contain a Three Lick Bed equivalent. A new division of Antrim at the stratigraphic position of Foerstia should be considered.