1873 | Colorado Plateau - Historic Image from the 1873 Wheeler Survey
"Canyon of the Colorado River near the mouth of the San Juan River in Arizona. Photo by T.H. O'Sullivan.U.S. Geographical Surveys West of the One Hundredth Meridian (Wheeler Survey, 1873 Expedition)." The rocks exposed in the cliff in the foreground are marvelously cross-bedded. Look closely and on the right side of the picture you'll see the number 13 is inscribed. (Image courtesy of the US Geological Survey Photographic Library (http://libraryphoto.cr.usgs.gov/index.html).