Grand Canyon much younger than previously thought?

The Grand Canyon took its present form just five to six million years ago — more recently than previously thought, a new study suggests. Previous studies had claimed that the canyon, which snakes through the US state of Arizona, was 70 million years old. The latest study agrees that some segments are very old, but the full system is quite young. "The 'old canyon model' has argued that the Grand Canyon was carved 70 million years ago. We are refuting that," said 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. We show that the Colorado River used some old segments as it found its path to the Gulf of California in the past six million years." The experts used thermochronology to ascertain timing of the formation of four of the canyon's five segments. It was found that two of the three central segments — known as the 'Hurricane' segment and the 'Eastern Grand Canyon' — were ancient. While the 'Hurricane' segment was formed 50 to 70 million years ago, the 'Eastern Grand Canyon' was incised 15 to 25 million years ago. The researchers say the two end segments of the canyon — known as the 'Marble' and the 'Westernmost Grand Canyon' — were carved in the last five to six million years.