Grand Canyon formed much recently than thought

The world famous Grand Canyon took its present form just five to six million years ago - much recently than previously thought, a new study suggests.
Previous studies had claimed that the canyon, which snakes through the US state of Arizona, was perhaps 70 million years old.
The latest investigation agrees that some segments are very ancient, but the full system is quite young, the BBC reported.
"The 'old canyon model' has argued that the Grand Canyon was carved 70 million years ago in the same place and to nearly the same depth as the modern canyon. We are refuting that," said Prof Karl Karlstrom from the University of New Mexico, Albuquerque.

"We are also refuting the 'young canyon model', which claims the canyon was cut entirely in the last six million years. Instead, we show that the Colorado River used some old segments as it found its path from the Rockies to the Gulf of California in the past six million years.
Researchers used thermochronology to constrain the timing of the formation of four of the Grand Canyon's five segments.

The findings show that two of the three central segments - known as the "Hurricane" segment and the "Eastern Grand Canyon" - were indeed ancient palaeocanyons.
While the "Hurricane" segment was cut between 50 and 70 million years ago; the "Eastern Grand Canyon" was incised some 15 to 25 million years ago.

However, the researchers determined that the two end segments of the canyon - known as the "Marble Canyon" and the "Westernmost Grand Canyon" - were carved in the last five to six million years.
The study was published in the journal Nature Geoscience.