R.B. Marshall, Chief Geographer. Geo. R. Davis, Geographer in charge. Topography by N.E. Ballmer, W.G. Carson, E.G. Hamilton, and N.A. Huth. Control by R.C. Seitz and C.F. Urquhart. Surveyed in 1918. Surveyed in cooperation with the War Department and the State of California. Polyconic projection. North American datum. 5000 yard grid based upon U.S. zone system, G. [Vertical] datum is mean sea level.