1. Arizona (Coconino County), Bright Angel quadrangle Maps Stanford University Public content Geological Survey (U.S.), Douglas, Edward Morehouse, 1855-1932, and Matthes, François, 1874-1948. U.S. Geological Survey ; E.M. Douglas, geographer in charge ; topography by Franc̜ois E. Matthes. Surveyed in 1902-1903. "Contour interval 50 feet....