1892. 2011-05-23T20:06:43Z. 2015-10-21T14:59:48Z. Geological Survey (U.S.). U.S. Dept. of the Interior, Geological Survey. English. Public. Dickenson County (Va.), Floyd (Ky.), Kentucky, Knott (Ky.), Letcher (Ky.), Pike County (Ky.), Virginia, and Wise County (Va.).