Scientific Investigations Map 2994

Stratigraphic Framework of Cambrian and Ordovician Rocks in the Appalachian Basin from Sequatchie County, Tennessee, through Eastern Kentucky, to Mingo County, West Virginia

By Robert T. Ryder, Robert D. Crangle, Jr., John E. Repetski, and Anita G. Harris

This report is available online in PDF format: SIM 2994 (Opens the PDF file in a new window. ) (30.4 MB)

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Cross section H-H' is the seventh in a series of restored cross sections constructed by the lead author to show the stratigraphic framework of Cambrian and Ordovician rocks in the Appalachian basin from Pennsylvania to Tennessee. The sections show complexly intertongued carbonate and siliciclastic lithofacies, marked thickness variations, key marker horizons, unconformities, stratigraphic nomenclature of the Cambrian and Ordovician sequence, and major faults that offset Proterozoic basement and overlying lower Paleozoic rocks. Several of the drill holes along the cross section have yielded a variety of whole and (or) fragmented conodont elements. The identifiable conodonts are used to differentiate strata of Late Cambrian, Early Ordovician, and Middle Ordovician age, and their conodont color alteration index (CAI) values are used to establish the thermal maturity of the sequence. Previous cross sections in this series are G-G', F-F', E-E', D-D', C-C', and B-B'. Many of these cross sections (B-B', C-C', D-D', and G-G') have been improved with the addition of gamma-ray log traces, converted to digital images, and made accessible on the Web.

Suggested citation:

Ryder, R.T., Crangle, R.D., Jr., Repetski, J.E., and Harris, A.G., 2008, Stratigraphic framework of Cambrian and Ordovician rocks in the Appalachian basin from Sequatchie County, Tennessee, through eastern Kentucky, to Mingo County, West Virginia: U.S. Geological Survey Scientific Investigations Map 2994, 1 sheet. (Also available online at


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