Aspen District Sheet.
Aspen District Sheet. Geology Sheet VI . U. S. Geological Survey, Charles D. Walcott, Director. Monograph XXXI. A.H. Thompson, Geographer. Morris Bien, Topographer in charge. Triangulation by Morris Bien. Topography by F.F. Grove. Surveyed in 1891. S.F. Emmons, Geologist in charge. Geology by J.E. Spurr. Assistant, G.W. Tower. Julius Bien & Co. Lith. N.Y. (1898)
David RumseySpurr, Josiah Edward
1898
1898
United States Geological Survey
1:31 000