Ishawooa Sheet. Geology Sheet XV. Monograph XXXII. Yellowstone National Park. U.S. Geological Survey. Charles D. Walcott, Director. 1904. Julius Bien & Co. Lith. N.Y. A. H. Thompson, Geographer. Triangulation and Topography by Frank Tweedy. Surveyed in 1893. Geology by Arnold Hague, Geologist in charge, Assisted by Thomas A. Jaggar Jr., Surveyed in 1893 and 1897.