Keywords: stereoscopic stereophotography stereophotographs historical usgs history geology mapping black and white blackandwhite bnw stereograph blackandwhite monochrome outdoor mountain landscape black and white Grand Canyon National Park, Arizona. The Cinder Cone near the foot of Toroweap.U.S. Geographical and Geological Survey of the Rocky Mountain Region (Powell Survey) Grand Canyon National Park, Arizona. The Cinder Cone near the foot of Toroweap.U.S. Geographical and Geological Survey of the Rocky Mountain Region (Powell Survey) |