2006. 2012-01-13T19:48:51Z. 2012-03-05T17:33:06Z. Ryder, Robert T. U.S. Geological Survey ; For sale by U.S. Geological Survey, Information Services. English. Public. Appalachian Basin, Ohio, West Virginia, Appalachian Basin., Ohio., and West Virginia. Silurian.
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1999. 2002-06-01T04:00:00Z. 2016-07-16T21:16:14Z. Geological Survey (U.S.). U.S. Geological Survey ; For sale by U.S. Geological Survey, Information Services. English. cartographic image. Public. Appalachian Basin, United States, and Appalachian Basin. Pennsylvanian and From 280 to 310 million years ago.