Magnificent Grand Canyon much younger than thought: Study

The Grand Canyon - one of the most iconic landscapes in the United States - was not formed 70 million years ago as earlier theories have suggested.

Marble Canyon, at the eastern edge of the Grand Canyon in Arizona, is just 5 to 6 million years old when older, shorter canyons linked together to form the complete structure, says new research.

"I think we have resolved the 140-year-long debate about the age of the Grand Canyon," said Karl Karlstrom, a geologist at University of New Mexico in Albuquerque.

The study focused on when exactly the Colorado river began cutting through those layered rocks - forming the three-dimensional chasm that tourists make a beeline to watch.

Karlstrom and his team used the helium technique, as well as other dating methods, to study rocks from the length of the Grand Canyon.

The team found that two stretches near the canyon's middle are indeed quite ancient.

The eastern Grand Canyon is 15 to 25 million years old and another stretch downriver is 50 to 70 million years old, said the study appeared in the journal Nature Geoscience.

But two other segments - Marble Canyon, the farthest stretch upriver studied and the westernmost Grand Canyon - were carved far more recently.

"Different segments of the canyon did not get linked together to form the Grand Canyon with the Colorado River running through it until 5-6 million years ago," explained Karlstrom.

It remains to be seen where the debate might move next, the study concluded.