Scientists believe a section of Grand Canyon could be 70 million years old

The Grand Canyon as we know it was formed between five and six million years ago, which is youthful in geological terms, but parts of it could be as old as 70 million years, scientists said.

Experts have debated for nearly 150 years about the age of the canyon, wrangling over how long it took for the grandiose feature to be gouged out by the Colorado River and its tributaries.

Reporting in the journal Nature Geoscience on Sunday, researchers in the United States said they had dated rock samples from the length of the 446-kilometre canyon and used computer simulations of the topography in their new appraisal.

Two middle sections, called the Hurricane segment and the Eastern Grand Canyon segment, were formed between 50 and 70 million and between 15 and 25 million years ago respectively, they believe.

But two other sections are far younger - they were carved out only between five and six million years ago. Their creation linked up all four segments, forming a single canyon.

Today, the canyon averages about 1,230 metres in depth, falling to about 1,850 metres at its deepest point and 29 kilometres at its widest.