Geologic map of Morrill County, Nebraska / U.S. Department of the Interior, U.S. Geological Survey ; by James B. Swineheart and Robert F. Diffendal, Jr. ; prepared in cooperation with the University of Nebraska--Lincoln, Institute of Agriculture and Natural Resources, Conservation and Survey Division
Miscellaneous investigations series ; map I-2496 Miscellaneous investigations series (Geological Survey (U.S.)) ; map I-2496.
1 map : color ; 100 x 98 cm, on sheet 104 x 137 cm., folded in envelope 30 x 24 cm.
Relief shown by contours and spot heights. "With a section on New ⁴⁰Ar/³⁹ Ar laser fusion ash dates from the Wildcat Ridge, Nebraska by C.C. Swisher, III." Includes text, bibliography, 1 table, and index and location maps.