FILE - In this Dec. 7, 2006 file photo, tourists visit the Hualapai Indian Reservation along the western end of the Grand Canyon. A new study published in the journal Science Thursday, Nov. 29, 2012, suggests the western Grand Canyon formed 70 million years ago. Some scientists disagree and believe the canyon was mainly carved by the Colorado River in the past 5 to 6 million years. (AP Photo/Jake Bacon, File)
Grand Canyon, Hualapai Indian Reservation
FILE - In this Dec. 7, 2006 file photo, tourists visit the Hualapai Indian Reservation along the western end of the Grand Canyon. A new study published in the journal Science Thursday, Nov. 29, 2012, suggests the western Grand Canyon formed 70 million years ago. Some scientists disagree and believe the canyon was mainly carved by the Colorado River in the past 5 to 6 million years. (AP Photo/Jake Bacon, File)
