New research suggests that the Grand Canyon formed within the last 5-6 million years. The findings run counter to recent studies showing that the famous canyon dates back 70 million years.
The rocks that form the canyon have been in place for as much as 1.8 billion years, and several smaller canyons that are now part of the Grand Canyon may have existed for tens of millions of years, but the Colorado River only started carving out the full chasm within the last 5-6 million years, the study explains.
Using several dating techniques,
including helium measurements, Karlstrom and his team determined that certain
areas of the eastern Grand Canyon are 15-25 million years old. Further down the
river, there is an area that is 50-70 million years old.
“Different segments of the canyon have different histories and different ages, but they didn’t get linked together to form the Grand Canyon with the Colorado River running through it until 5 to 6 million years ago,” Karl Karlstrom, a geologist at the University of New Mexico in Albuquerque, told Nature News, the blog associated with the journal Nature. His work is published in Nature Geoscience. Fellow geologists do not all agree.
In an earlier study, Rebecca Flowers of the University of Colorado Boulder and Kenneth Farley of the California Institute of Technology in Pasadena, used temperature a temperature dating technique to conclude that the full canyon dates 70 million year.
“It will take a bit more time to understand fully why their interpretations are so different from ours,” she told Nature News.
“I think we’ve resolved the 140-year-long debate about the age of the Grand Canyon,” Karlstrom said.
But as Nature News explained, “Small changes in assumptions can mean big changes in interpretation. For instance, some studies assume that the ground temperature at the surface is 25 degrees Celsius, whereas Karlstrom’s team used a range of 10‒25 degrees. Such changes mean big differences for interpreting how long a particular piece of apatite has been buried.”