The Grand Canyon is a geological Frankenstein, made of old and new canyon parts, according to new research published in the Jan. 26 issue of Nature Geoscience. The work may be the beginning of the end a very long debate that has put the canyon at anywhere from 70-million-years-old to as young as 5 or 6 million-years-old.
"I think we've got the solution to a 140-year-old problem," said Karl Karlstrom of the University of New Mexico in Albuquerque.
The solution comes in the form of a technique called apatite fission-track dating which allow geologists to determine how long rocks of the canyon have been cooled from the steamy warmth a kilometer or two underground, to the chilly surface temperature of the Earth -- what is called their thermal histories.
By figuring out the thermal histories of rock samples taken from the base of different segments of the Grand Canyon and the adjacent canyon rims 1,500 meters above, Karlstrom and his colleagues were able to determine how long ago the rocks were unearthed by the canyons, which were being cut by a river.