1. Lithofacies and stratigraphic nomenclature of part of the Upper Ordovician section of Kentucky [cartographic material] Yale Public content 1979. 2014-09-10T17:26:37Z. 2021-06-01T21:36:14Z. Weir, Gordon W. (Gordon Whitney), 1922-2011. U.S. Geological Survey. English. Public. Kentucky and Kentucky. Ordovician and From 425 to 500 million years ago.