Megafloods carved land in Idaho -- and on Mars?

High-resolution topographic map of Box Canyon, Idaho.

A new study of Idaho’s Box Canyon, which is similar to canyons on Mars, may shake up our view of how water sculpted the landscape on the Red Planet.

For a long time, geologists have assumed that Box Canyon was formed through gradual erosion, as groundwater seeped through the canyon walls and wore the rock away. They also figured this was true for other canyons that are made of volcanic rock and shaped like Box Canyon – which includes many of the canyons on Mars.

All these canyons are sort of stubby, ending at a round, steep wall. Researchers call them “amphitheater-headed” canyons.

But, Michael Lamb and his colleagues at the University of California, Berkeley took a close look at Box Canyon. They studied the large boulders that seemed to have been plopped on the ground out of nowhere, and several depressions, or "plunge pools," that appear to have been the site of ancient waterfalls.

The researchers concluded that Box Canyon was actually scoured out by a massive flood about 45,000 years ago. The water probably came from the melting ice sheets that lay to the north. It would have blasted through the canyon at an incredibly fast speed, Dr. Lamb and his colleagues estimate.

By extension, it’s also possible that these megafloods occurred on Mars.

This research appears in the 23 May issue of the journal Science.

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