| John K. Hillers Walls of limestone [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. 203] 1872 Stereoview Library of Congress, Prints and Photographs Division Reproduction Number: LC-DIG-stereo-1s00763 (digital file from original photo, front) LC-DIG-stereo-2s00763 (digital file from original photo, back) LL/109096
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