Glacial Lake Missoula and the Channeled Scabland: Missoula, Montana to Portland, Oregon, July 20 - 26, 1989

Published by the American Geophysical Union as part of the Field Trip Guidebooks Series, Volume 310. This field guide describes the geology of Pleistocene glacial Lake Missoula and the Channeled Scabland of the northwestern United States. Catastrophic floods created by outbursts from this glacially dammed lake created the largest known floods on this planet. The route of this trip, shown in Figure 1, follows the path of the water from Missoula, Montana, through glacial Lake Missoula, on past the area of ice dams in Idaho, down some of the major scabland channel systems and slackwater basins in Washington, and through the Columbia River Gorge to Portland, Oregon. In 1933, the Sixteenth Session of the International Geological Congress included an excursion into the Channeled Scabland that was prepared by J Harlen Bretz of the University of Chicago. Professor Bretz's work on the Channeled Scabland covered over 40 years. Now, we meet in 1989 on the same subject to see the evidence and vindication of his work, and to examine new research on this important event in Quaternary geology.