John K. Hillers 1872 Boulders [U.S. topographical and geological survey of the valley of the Colorado River of the west, by J.W. Powell and A.H. Thompson. No. 189]
Stereoview Library of Congress, Prints and Photographs Division Reproduction Number: LC-DIG-stereo-1s00755 (digital file from original photo, front) LC-DIG-stereo-2s00755 (digital file from original photo, back)
