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Imagine That! - Water Cuts Through Rock

Imagine That!
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Imagine That! - Water Cuts Through Rock

Credit: NSF/Finger Lakes Productions International

Audio Transcript:

The Earth and its amazing wonders didn't always look this way... erosion, floods, rock, and sun helped make it what it is today.

Imagine That!

If you've ever hiked in a canyon or gorge, you've seen the ancient battle between water and earth. It's a fight that continues today. Researchers at the University of Vermont recently nailed down some dates and scores on the never ending game. By examining rock samples from Great Falls, outside of DC, and Holtwood Gorge in Pennsylvania, they were able to determine these natural wonders' birthdays.

The key to the number of candles on the cakes is in the rock. Researchers recently analyzed the samples for the presence of 10-beryllium -- a rare isotope only produced when the earth's surface is bombarded by invisible cosmic rays, something that never happens underwater. So they were able to measure approximately when these rocks and surfaces were exposed high and dry, after the rivers that created them cut deep canyons.

Both gorges were created about thirty-five thousand years ago. The same time that the Earth experienced an extended cold and stormy spell, leading to lots of large, damaging floods. These floods were a secret weapon for the rivers, increasing their ability to cut through very dense bedrock and turn a new direction, leaving gorgeous gorges and "great falls" in their wake. I'm Eric Phillips.

"Imagine That!" covers projects funded by the U.S. government's National Science Foundation. Federally sponsored research -- brought to you by you! Learn more at

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