1. Map of the structural geology of Letcher County, Kentucky Yale Public content 1926. 2018-05-09T18:23:25Z. 2018-09-05T19:39:44Z. Robinson, L. C., cartographer. Kentucky Geological Survey,Williams-Webb Co. English. cartographic image. Public. Kentucky, Letcher County, Letcher County (Ky.), and Letcher County.