/ Modified jul 28, 2015 6:59 a.m.

How Old Is Grand Canyon? 'Only' 6 Million Years

Claim of 70 million years disputed in new geological research at ASU.

grand-canyon_617x347 Sunset at Yavapai Point, along the Grand Canyon's South Rim.

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By By Melissa Sevigny, Arizona Science Desk

New research supports the long-held hypothesis that the Grand Canyon is as young as 6 million years. That’s what geologists originally believed before a different study claimed it was tens of millions of years older.

The study, which was conducted by geologists at Arizona State University, compares the western Grand Canyon with the Grand Wash Cliffs. It found that the canyon is steeper than the cliffs, which suggests erosion started more recently.

“So our conclusion is that it’s younger than the activity on the Grand Wash Fault,” said Andrew Darling, lead author of the study. “If the canyon’s younger than the fault, that would be consistent with the 6 million year old canyon age.”

A previous study in 2012 revitalized research and debate when it claimed the Grand Canyon might be as old as 70 million years. That study looked at the decay of radioactive elements in rocks. The ASU study looked at geomorphology, particularly erosion rates.

The Arizona Science Desk is a collaboration of public broadcasting entities in the state, including Arizona Public Media.

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