Although Major John Wesley Powell was not the first geologist to view the canyon lands, his two daring boat trips down the Green and Colorado Rivers in 1869 and 1871 made history by bringing to light the first descriptions of the geography and geology of what was then the largest remaining uncharted wilderness in the United States. Many landmarks along the canyons in the park were named by Powell and his men during those explorations. J. S. Newberry is thought to have been the first geologist to view the canyon lands—at least he seems to have been the first one whose observations were recorded (1861), but the more comprehensive findings of Powell (1875) were the ones that made history. The 100th anniversary of Major Powell’s pioneer exploration of the Green and Colorado Rivers was commemorated in 1969 by a national centennial sponsored jointly by the U.S. Department of the Interior, the Smithsonian Institution, the National Geographic Society, and many other organizations. This touched off many magazine and newspaper articles, several commemorative programs and dedications, and several publications of lasting interest. Noteworthy among the latter is U.S. Geological Survey Professional Paper 669 entitled “The Colorado River Region and John Wesley Powell.” Of its four separate parts, two are of special interest to our Canyonlands story: part A, “John Wesley Powell: Pioneer Statesman of Federal Science,” by Rabbitt (1969) and part C, “Geologic History of the Colorado River,” by Hunt (1969). An interesting history of the National Park Service by Everhart (1972) was published as part of the national park centennial effort. The Powell Society, Ltd., of Denver, Colo., was founded mainly to publish four “River Runners’ Guides to the Canyons of the Green and Colorado Rivers, with Emphasis on Geologic Features,” covering five reaches of the two rivers from Flaming Gorge Dam, Utah, to Grand Canyon, Ariz. One of these by Mutschler (1969) covers Labyrinth, Stillwater, and Cataract Canyons, all in Canyonlands National Park. Another guidebook by Baars and Molenaar (1971) covers the Colorado River from about Potash, Utah, to the confluence with the Green, and Cataract Canyon. It is difficult to realize that thousands of people annually now boat down the canyons Powell dared to explore without knowledge of the dangers that lay ahead.