My deep appreciation goes to Bates Wilson, former superintendent of Canyonlands National Park, and to Joe Carithers, former assistant superintendent, for their splendid cooperation in supplying data and information and for making available four-wheel-drive vehicles. I also wish to thank Chuck Budge, former chief ranger; Dave May, assistant chief ranger; Joe Miller, former maintenance engineer; Bob Kerr, new superintendent; Maxine Newell, park historian and member of the staff at Arches National Park; Jerry Banta, park ranger at Arches; and Dave Minor, district ranger for the Needles district, for their many favors. I am grateful to several colleagues and friends for the loan of photographs, for geologic help and data, and for reviewing this report. I am also deeply grateful to my wife Ruth for accompanying me on all the field work and for her help and encouragement. Selected references Baars, D. L., and Molenaar, C. M., 1971, Geology of Canyonlands and Cataract Canyon: [Durango, Colo.] Four Corners Geol. Soc., 6th Field Conf., Cataract Canyon River exped., 99 p. Baker, A. A., 1933, Geology and oil possibilities of the Moab district, Grand and San Juan Counties, Utah: U.S. Geol. Survey Bull. 841, 95 p. ____ 1946, Geology of the Green River Desert-Cataract Canyon region, Emery, Wayne, and Garfield Counties, Utah: U.S. Geol. Survey Bull. 951, 122 p. Baker, Pearl, 1971, The Wild Bunch at Robbers Roost: New York, Toronto, London, Abelard-Schuman, 224 p. Bishop, Captain Francis Marion, 1947, Bishop’s Journal edited by Charles Kelley, _in_ Biographical sketches and original documents of the second Powell expedition of 1871-72: Utah State Hist. Soc., Utah Hist. Quart., v. 15, p. 159-238. Crampton, C. G., 1964, Standing up country, the canyon lands of Utah and Arizona: New York, Alfred A. Knopf (Utah Univ. Press, in association with Amon Carter Mus. Western Art), 191 p. Dellenbaugh, F. S., 1902, The romance of the Colorado River: New York, G. P. Putnam’s Sons, 399 p. [reprinted 1962 by Rio Grande Press, Chicago, III.] ____ 1962, A canyon voyage: The narrative of the second Powell Expedition down the Green-Colorado River from Wyoming, and the explorations on land, in the years 1871 and 1872: New Haven and London, Yale Univ. Press, Foreword by William H. Goetzmann, 277 p. Everhart, W. C., 1972, The National Park Service, Praeger Library of U.S. Government Departments and Agencies No. 13: New York, London, Praeger Publishers, Inc., 276 p. Findley, Rowe, 1971. Canyonlands—realm of rock and the far horizon: Nat Geog. Mag., July, p. 71-91. Follansbee, Robert, 1929, Upper Colorado River and its utilization: U.S. Geol. Survey Water-Supply Paper 617, 394 p. Gilluly, James, Waters, A.