William Henry Jackson, “Green River, Canyon of Desolation, Sumner’s Amphitheater,” (1871); The National Archives and Records Administration
Green_River,_Canyon_of_Desolation._Sumner’s_Amphitheater_-_NARA_-_517174
William Henry Jackson, “Green River, Canyon of Desolation, Sumner’s Amphitheater,” (1871); The National Archives and Records Administration