The “grand excursion” of the Fifth International Geological Congress (1891) Celebrating geological exploration of the American West

The first International Geological Congress (IGC) ever to be convened in North America (5 th 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 stagecoach across the Great Plains and Rocky Mountains to Yellowstone and the Grand Canyon for some 90 participants was organized by Samuel F. Emmons who had earlier served with the Fortieth Parallel Survey. Other trip leaders were G. H. Williams and I. C. White (Appalachian geology), J. P. Iddings (Montana geology), Arnold Hague (Yellowstone National Park), G. K. Gilbert (Basin and Range faulting, history of pluvial Lake Bonneville, and Niagara Falls region), J. W. Powell (Grand Canyon region), and C. W. Cross (Colorado geology). The stature of the U.S. Geological Survey in this golden age of geology was reflected in the large proportion of its members among IGC field-trip leaders and/or guidebook contributors.