Friday, October 30, 2009

Pleistocene debris flows much larger in Catalina foothills


AZGS geologist Ann Youberg's talk at the Geological Society of America annual meeting last week was at 3 pm on the last day, usually a deadly time as people bail out to catch planes home. But her room was pretty well packed, with us late arrivers filling in around the walls.

Ann reported that she and co-workers found that volume of late Pleistocene debris flows in the Catalina Mountains foothills on the north side of Tucson, are in the range of 10 million cubic meters, two orders of magnitude larger than the biggest debris flows resulting from the severe events of summer of 2006. [right, 2006 debris flow in Soldier Canyon. Credit, AZGS]

The team concluded that "climatic change between the late Pleistocene and the Holocene affected storm meteorology and seasonality thus causing changes in debris-flow initiation mechanisms, available source material, and initiation-source areas.
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Ref: COMPARISON OF LATE PLEISTOCENE AND HISTORICAL DEBRIS-FLOW VOLUMES AND INITIATION MECHANISMS, SANTA CATALINA MOUNTAINS, ARIZONA

YOUBERG, Ann1, MAGIRL, Christopher S.2, WEBB, Robert H.3, GRIFFITHS, Peter G.3, and PEARTHREE, Philip A.4, (1) Hydrology and Water Resources, University of Arizona, 1133 E. James E. Rogers Way, Tucson, AZ 85721, ann.youberg@azgs.az.gov, (2) U.S. Geological Survey, 934 Broadway, Suite 300, Tacoma, WA 98402, (3) U.S. Geological Survey, 520 N. Park Avenue, Suite 221, Tucson, AZ 85719, (4) Arizona Geological Survey, 416 W. Congress St, Suite 100, Tucson, AZ 85701

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