[Illustration: Dinosaur] Additional Reading Many reports covering various aspects of the area have been cited in the text by author and year, and these plus a few additional ones are listed below under “Selected References.” A few of general or special interest should be mentioned, however. Between 1926 and 1931 virtually the entire area now included in the park was mapped geologically in three classic reports—two by Baker (1933, 1946) and one by McKnight (1940). These men and their field assistants mapped the area by use of the plane table and telescopic alidade without benefit of modern topographic maps or aerial photographs, except for topographic maps of narrow stretches along the Green and Colorado Rivers made under the direction of Herron (1917). Only small sections could be reached by automobile, so nearly all the area was traversed using horses or by hiking. During the uranium boom of the early and middle 1950’s, the U.S. Geological Survey remapped the topography of most of the area at a scale of 1:24,000 and also remapped the geology of much of the area at this same scale. The southern part of the Needles district was mapped by Lewis and Campbell (1965). The geologic mapping west of the Green and Colorado Rivers was done by F. A. McKeown, P. P. Orkild, C. C. Hawley, and others; that east of the Colorado River and a little between the two rivers was done by E. N. Hinrichs and others. Only four of the geologic maps have been published (Hinrichs and others, 1967, 1968, 1971a, b), but all this work and the older reports were used by Williams (1964) in compiling the 1:250,000-scale geologic map of the Moab quadrangle, by Williams and Hackman (1971) in compiling a similar map of the Salina quadrangle, and by Haynes, Vogel, and Wyant (1972) in compiling a similar map of the Cortez quadrangle. These three maps show the geology of the entire park. The 1970 issue of the Naturalist in which the cited papers by Jennings, Newell, and Stokes appear also contains other papers on Canyonlands National Park, including one on the plants. Several early reports on the Green and Colorado Rivers and their potential utilization contain a wealth of information and many fine photographs—two reports on the Colorado River by La Rue (1916, 1925), one on the Green River by Wooley (1930), and one on the upper Colorado River (above the confluence) by Follansbee (1929). For those who wish to learn more about the science of geology, I suggest the textbook by Gilluly, Waters, and Woodford (1968). Acknowledgments