

Using a new dating tool, a team of scientists came up with a different age for the western section of the gorge in the US southwest, challenging conventional wisdom that much of the canyon was scoured by the mighty Colorado River in the last five million to six million years.

Not everyone is convinced with the latest viewpoint published online in the journal, Science. Critics contend the study ignores a mountain of evidence pointing to a geologically young landscape and they have doubts about the technique used to date it.

The notion that the Grand Canyon existed during the dinosaur era is "ludicrous", said geologist Karl Karlstrom of the University of New Mexico in Albuquerque.


Some five million tourists flock to Arizona each year to marvel at the 445km-long chasm, which plunges a mile deep in some places. It's a geologic layer cake with the most recent rock formations near the rim stacked on top of older rocks that date back two billion years.



To come up with the age, the team crushed rocks collected from the bottom of the canyon to analyse a rare type of mineral called apatite. The mineral contains traces of radioactive elements that release helium during decay, allowing researchers to calculate the passage of time since the canyon eroded.


Lead researcher Rebecca Flowers of the University of Colorado Boulder realises not everyone will accept this alternative view, which minimizes the role of the Colorado River.
