THE "GRAND EXCURSION" OF THE 5TH INTERNATIONAL GEOLOGICAL CONGRESS [1891]: CELEBRATING GEOLOGICAL EXPLORATION IN THE AMERICAN WEST

The first International Geological Congress (IGC) ever to be convened in North America (5th IGC: Washington, D. C., 1891) allowed American geologists to present results of pioneering mapping in the American West to an international community in a field setting. A 25-day "grand excursion" by rail and stage coach across the Great Plains and Rocky Mountains to Yellowstone and the Grand Canyon for 88 participants was organized by Samuel Franklin Emmons who had earlier served with the 40th Parallel Survey and who for the trip reviewed the geology of Idaho, northern Utah, western Colorado and the Great Plains. Among other trip leaders were G. H. Williams (Appalachian geology), J. P. Iddings (Montana geology), Arnold Hague (Yellowstone National Park), G. K. Gilbert (Basin-Range faulting, history of pluvial Lake Bonneville and Niagara Falls region), J. W. Powell (Grand Canyon region) and Whitman Cross (Colorado geology). Such broad exposure to American geology was complemented by Congress symposia of universal relevance: "Time correlation of clastic rocks-physical and biotic methods", "Genetic classification of Pleistocene deposits" and "General geological color schemes for maps". The stature of the U. S. Geological Survey in this golden age of geology was reflected in the large proportion of its members among Congress participants (a third), organizers and trip leaders.