Databas of USGS Map I-1970, [electronic resource] : map showing the thickness and character of Quaternary sediments in the glaciated United States east of the Rocky Mountains / by D.R. Soller, P.H. Packard, and C.P. Garrity.
Imprint
[Denver, CO] : U.S. Dept. of the Interior, U.S. Geological Survey, 2012.