In 2002, a colossal Texan flood carved an impressive 2.2-kilometer (1.4-mile) wide and 7-meter (23-foot) deep canyon in less than a week.
Generally, canyons are carved on a timescale of thousands to millions of years. But every now and again, a catastrophic megaflood can do the same job in a geologic blink of an eye.
Scientists believe such outbursts are responsible for shaping different landscapes on ancient Earth and Mars. The Texas flood provided an opportunity for researcher Michael Lamb at the California Institute of Technology and his team to study this process in action.
Megafloods are extremely rare. “There are none that I know of that have carved a canyon into rock in one event. There have been others where the erosion was into loose sediment,” Lamb told Discovery News in an email.
In the case of the Grand Canyon, repeated episodes of flowing water gradually wore down the rocky surface. In Texas, the flood just ripped up the underlying bedrock -- "plucked" it, in geological parlance -- into large boulders and transported them downstream, according to a new study in Nature Geoscience.
Breaking up bedrock is no easy feat, however, even for a super-sized flood. And until now, scientists had no explanation for how bedrock can just spontaneously shatter.
A closer look at the bedrock in Texas revealed that the ground was already fractured and this set the stage for the megaflood to go on a plucking-spree.
“This tells us that the dominant erosion process is strongly controlled by the underlying rock type,” Lamb explained.
So, just like you can’t judge a book by it’s cover, you can’t simply characterize a flood by it’s water.
Images: Michael Lamb, California Institute of Technology
Tags: Geology, Geophysics, Natural Disasters, Scientific Discoveries, Water
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