Channeled Scablands

Drumheller Channels

The Channeled Scablands are a barren, relatively soil free landscape in eastern Washington, scoured clean by a flood unleashed when a large glacial lake drained. They are a geologically unique erosional feature in the U.S. state of Washington. They were created by the cataclysmic Missoula Floods that swept periodically across eastern Washington and down the Columbia River Plateau during the Pleistocene epoch. Geologist J Harlen Bretz coined the term in a series of papers in the 1920s. Debate over the origin of the Scablands raged for four decades and is one of the great debates in the history of earth science. The Scablands are also important to planetary scientists as perhaps the best terrestrial analog for the Martian outflow channels.

Geology

River valleys formed by erosion normally have a 'V' cross section, and glaciers leave a 'U' cross section. The Channeled Scablands have a rectangular cross section and are spread over immense areas of eastern Washington. They exhibit a unique drainage pattern that appears to have an entrance in the northeast and an exit in the southwest. The eroded channels also show an anastomosing, or braided, appearance. There are also immense potholes and ripple marks, much larger than those found on ordinary rivers. When first studied, no known theories could explain the origin of these features.

Bretz conducted research and published many papers during the 1920s describing the Channeled Scablands. His theories of how they were formed required short but immense floods (500 cubic miles of water), for which Bretz had no explanation. Bretz's theories met with vehement opposition from geologists of the day, who tried to explain the features with uniformitarian theories.

J.T. Pardee first suggested in 1925 to Bretz that the draining of a glacial lake could account for flows of the magnitude needed. Pardee continued his research over the next 30 years, collecting and analyzing evidence that eventually identified Lake Missoula as the source of the Missoula Floods and creator of the Channeled Scablands.

Pardee's and Bretz's theories were accepted only after decades of painstaking work and fierce scientific debate. Research on open channel hydraulics in the 1970s put Bretz's theories on solid scientific ground. In 1979 Bretz received the highest medal of the Geological Society of America, the Penrose Medal, to recognize that he had developed one of the great ideas in the earth sciences.

See also

• Coulee
• Glacial lake outburst flood
• Drumheller Channels National Natural Landmark
• Dry Falls
• Giant current ripples
• Diluvium
• Outflow channels
• Altai flood

References

• Bretz, J Harlen (1923), "The Channeled Scabland of the Columbia Plateau." Journal of Geology, v.31, p.617-649.
• Bretz, J Harlen (1925), "The Spokane flood beyond the Channeled Scablands." Journal of Geology, v.33, p.97-115, 236-259.
• Bretz, J H.; Smith, H.T.U.; and Neff, G.E., (1956) "Channeled Scabland of Washington — New Data and Interpretations." Geological Society of America Bulletin, v.67, p.957-1049.
• Allen, John Eliot; Marjorie Burns; and Sam C. Sargent. (1986) Cataclysms on the Columbia. Portland, Oregon: Timber Press, ISBN 0-88192-215-3
• Soennichsen, John (2008), "Bretz's Flood: The Remarkable Story of a Rebel Geologist and the World's Greatest Flood", Seattle, Washington, Sasquatch Books, ISBN 978-1-57061-505-4

External links

• United States Geological Survey The Channeled Scablands of Eastern Washington
• Steven Dutch, University of Wisconsin - Green Bay, Channeled Scablands: Overview
• Historical Discussion
• PBS's NOVA: Mystery of the Megaflood
• Scablands in Google Maps
• Online book from the National Park Service about the geologic origins of the scablands.
• Sun Lakes-Dry Falls State Park in the Channeled Scablands
• Columbia Plateau Trail StatePark in the Channeled Scablands
• The Seattle Times' Pacific NW magazine - "Trailing an Apocalypse" - 30-Sep-2007
• The channeled scabland: a guide to the geomorphology of the Columbia Basin, Washington : prepared for the Comparative Planetary Geology Field Conference held in the Columbia Basin, June 5-8, 1978 / sponsored by Planetary Geology Program, Office of Space Science, National Aeronautics and Space Administration ; edited by Victor R. Baker and Dag Nummedal.
• Keenan Lee. Altai Flood
• ru: А. Н. Рудой. 1. Study diluvium: general provisions. Общие положения учения о дилювии. 2. Scablands. Скэбленд: экзотические ландшафты.
• Rudoy A.N. Glacier-dammed lakes and geological work of glacial superfloods in the Late Pleistocene, Southern Siberia, Altai Mountains, Quaternary International, 2002, Vol. 87/1, pp. 119-140.