prepared by National Park Service, Denver Service Center, for the Southwestern Pennsylvania Heritage Preservation Commission, United States Department of the Interior
[Geological Survey of Pennsylvania ; J.P. Lesley, state geologist, anthracite district ; Charles A. Ashburner, geologist in charge ; A.W. Sheafer and Frank A. Hill, assistant geologists]
Date
1882
Series
Report of progress (Geological Survey of Pennsylvania) ; AA