The images used in this website are scanned from original stereographs that were purchased as souvenirs 
          by Emma Sanor (from Minerva, Ohio) while visiting Yellowstone in 1916. 
          The stereographs are therefore older than that date (and have hence expired 
          their copyright). Stereo photography became extremely popular starting 
          in the early 1880's. The oldest date for any of these original images 
          was about 1884. Individual pages can be clicked on below. 
           
          For more information about Yellowstone National Park's 
            geology visit the U.S. Geological Survey's Yellowstone Volcano Observatory website at http://volcanoes.usgs.gov/yvo/. 
          Also visit the official National Park Service's website 
            for Yellowstone National Park at http://www.nps.gov/yell/. 
                  
                 Click here to see more 
                   geology tours of national parks. 
                
            The images used for this website were made from original stereographs (black and white stereo pairs) 
            that were scanned and manipulated into anaglyphs (3-D images) 
            with image processing software (Adobe PhotoShop). You will need red-and-cyan 
          stereo viewing glasses to get the 3-D visual effects.  
           
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