Grand Canyon 70M years old, study suggests
The awe-inspiring Grand Canyon was probably carved about 70 million years ago, much earlier than thought, a provocative new study suggests — so early that dinosaurs might have roamed near this natural wonder.
Using a new dating tool, a team of scientists came up with a different age for the gorge's western section, challenging conventional wisdom that much of the canyon was scoured by the mighty Colorado River in the last 5 million to 6 million years.
Not everyone is convinced with the latest viewpoint published online Thursday 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.
How the Grand Canyon became grand — with its vertical cliffs and flat plateaus — has been debated since John Wesley Powell navigated the whitewater rapids and scouted the sheer walls during his famous 1869 expedition.
About 5 million tourists flock to Arizona each year to marvel at the 277-mile-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 2 billion years.
Though the exposed rocks are ancient, most scientists believe the Grand Canyon was forged in the recent geologic past, created when tectonic forces uplifted the land that the Colorado River later carved.
The new work by researchers at the University of Colorado Boulder and the California Institute of Technology argued that canyon-cutting occurred long before that. They focused on the western end of the Grand Canyon occupied today by the Hualapai Reservation, which owns the Skywalk attraction, a horseshoe-shaped glass bridge that extends from the canyon's edge.
To come up with the age, the team crushed rocks collected from the bottom of the canyon to analyze 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.
Their interpretation: The western Grand Canyon is 70 million years old and was likely shaped by an ancient river that coursed in the opposite direction of the west-flowing Colorado.
Show commenting policy
TribLive commenting policy
You are solely responsible for your comments and by using TribLive.com you agree to our Terms of Service.
We moderate comments. Our goal is to provide substantive commentary for a general readership. By screening submissions, we provide a space where readers can share intelligent and informed commentary that enhances the quality of our news and information.
While most comments will be posted if they are on-topic and not abusive, moderating decisions are subjective. We will make them as carefully and consistently as we can. Because of the volume of reader comments, we cannot review individual moderation decisions with readers.
We value thoughtful comments representing a range of views that make their point quickly and politely. We make an effort to protect discussions from repeated comments either by the same reader or different readers.
We follow the same standards for taste as the daily newspaper. A few things we won't tolerate: personal attacks, obscenity, vulgarity, profanity (including expletives and letters followed by dashes), commercial promotion, impersonations, incoherence, proselytizing and SHOUTING. Don't include URLs to Web sites.
We do not edit comments. They are either approved or deleted. We reserve the right to edit a comment that is quoted or excerpted in an article. In this case, we may fix spelling and punctuation.
We welcome strong opinions and criticism of our work, but we don't want comments to become bogged down with discussions of our policies and we will moderate accordingly.
We appreciate it when readers and people quoted in articles or blog posts point out errors of fact or emphasis and will investigate all assertions. But these suggestions should be sent via e-mail. To avoid distracting other readers, we won't publish comments that suggest a correction. Instead, corrections will be made in a blog post or in an article.
- Driver’s license ban for immigrant children ends in Nebraska
- Historic Martha’s Vineyard lighthouse moves inland
- Texas rivers threaten cities downstream
- Health care law’s supporters encounter resistance from federal judge
- EPA’s temporary pesticide-free zones would protect commercial honeybees
- Tar balls wash ashore in California
- FCC wants to extend $1.7B phone subsidy to broadband
- Justice Department seeks info on medical scope in superbug outbreaks
- Detroit-area police officer to stand trial in driver’s beating
- North Carolina governor to veto marriage abstention bill
- Amtrak cameras to view operators