"In recent years geologists have hotly debated the age of the Grand Canyon. Some think it's young (just 6 million years old), while others argue that it dates back 70 million years — to the days of dinosaurs."

"Now one group says the Grand Canyon is neither young nor old. Instead, these geologists say, it's both."

"In the journal Nature Geoscience, Karl Karlstrom, of the University of New Mexico, and some colleagues describe a new creation story for the Grand Canyon. They think that about 6 million years ago, a river zigzagging a path across the Colorado plateau found part of its way through canyons that already existed."