Geology

Tracking the Deluge

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Science  19 Mar 2010:
Vol. 327, Issue 5972, pp. 1430
DOI: 10.1126/science.327.5972.1430-a
CREDIT: © LEIGHSMITHIMAGES/ALAMY

In the channeled scablands of eastern Washington State, great ripples and scoured rock, visible by satellite, mark periodic massive flood outbursts from a dammed glacial lake. Their recognition early in the 20th century revealed the huge scale of flooding that can occur on Earth and has influenced understanding of even larger flood features on Mars. The floods moved across the rough but low topography in the east and then had to drain through the high Cascade volcanic arc along the Columbia River gorge. Denlinger and O'Connell simulated several of the floods to reveal how rapidly the waters moved and how they scoured the landscape. The model, which starts with the detailed topography of the region and likely positions of the ice sheets, suggests that the floods surged westward, filling the Yakima Basin east of the Cascades to several hundred meters within 38 hours. Drainage through the Columbia Gorge was slower, taking about 3 weeks. Drainage of a single large lake, rather than multiple lakes, would have been sufficient to have formed the scablands.

Geol. Soc. Am. Bull. 122, 678 (2010).

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