1. Geologic cross section C-C' through the Appalachian basin from Erie County, north-central Ohio, to the Valley and Ridge Province, Bedford County, south-central Pennsylvania [cartographic material] Yale Public content 2012. 2012-07-11T14:05:56Z. 2013-03-18T22:05:30Z. Ryder, Robert T. U.S. Dept. of the Interior, U.S. Geological Survey ; For sale by U.S. Geological Survey, Information Services. English. Public. Appalachian Basin and Appalachian Basin.