Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

More Evidence for an Ancient Grand Canyon

30.11.2012
Caltech study supports theory that giant gorge dates back to Late Cretaceous period

For over 150 years, geologists have debated how and when one of the most dramatic features on our planet—the Grand Canyon—was formed. New data unearthed by researchers at the California Institute of Technology (Caltech) builds support for the idea that conventional models, which say the enormous ravine is 5 to 6 million years old, are way off.

In fact, the Caltech research points to a Grand Canyon that is many millions of years older than previously thought, says Kenneth A. Farley, Keck Foundation Professor of Geochemistry at Caltech and coauthor of the study. "Rather than being formed within the last few million years, our measurements suggest that a deep canyon existed more than 70 million years ago," he says.

Farley and Rebecca Flowers—a former postdoctoral scholar at Caltech who is now an assistant professor at the University of Colorado, Boulder—outlined their findings in a paper published in the November 29 issue of Science Express.

Building upon previous research (link to 2008 release: http://www.caltech.edu/content/grand-canyon-old-dinosaurs) by Farley's lab that showed that parts of the eastern canyon are likely to be at least 55 million years old, the team used a new method to test ancient rocks found at the bottom of the canyon's western section. Past experiments used the amount of helium produced by radioactive decay in apatite—a mineral found in the canyon's walls—to date the samples. This time around, Farley and Flowers took a closer look at the apatite grains by analyzing not only the amount but also the spatial distribution of helium atoms that were trapped within the crystals of the mineral as they moved closer to the surface of the earth during the massive erosion that caused the Grand Canyon to form.

Rocks buried in the earth are hot—with temperatures increasing by about 25 degrees Celsius for every kilometer of depth—but as a river canyon erodes the surface downwards towards a buried rock, that rock cools. The thermal history—shown by the helium distribution in the apatite grains—gives important clues about how much time has passed since there was significant erosion in the canyon.

"If you can document cooling through temperatures only a few degrees warmer than the earth's surface, you can learn about canyon formation," says Farley, who is also chair of the Division of Geological and Planetary Sciences at Caltech.

The analysis of the spatial distribution of helium allowed for detection of variations in the thermal structure at shallow levels of Earth's crust, says Flowers. That gave the team dates that enabled them to fine-tune the timeframe when the Grand Canyon was incised, or cut.

"Our research implies that the Grand Canyon was directly carved to within a few hundred meters of its modern depth by about 70 million years ago," she says.

Now that they have narrowed down the "when" of the Grand Canyon's formation, the geologists plan to continue investigations into how it took shape. The genesis of the canyon has important implications for understanding the evolution of many geological features in the western United States, including their tectonics and topography, according to the team.

"Our major scientific objective is to understand the history of the Colorado Plateau—why does this large and unusual geographic feature exist, and when was it formed," says Farley. "A canyon cannot form without high elevation—you don't cut canyons in rocks below sea level. Also, the details of the canyon's incision seem to suggest large-scale changes in surface topography, possibly including large-scale tilting of the plateau."

"Apatite 4He/3He and (U-Th)/He evidence for an ancient Grand Canyon" appears in the November 29 issue of the journal Science Express. Funding for the research was provided by the National Science Foundation.

Written by Katie Neith
Contact:
Caltech Media Relations
mr@caltech.edu

Brian Bell | EurekAlert!
Further information:
http://www.caltech.edu

More articles from Earth Sciences:

nachricht Mountain glaciers shrinking across the West
23.10.2017 | University of Washington

nachricht Climate change weakens Walker circulation
20.10.2017 | MARUM - Zentrum für Marine Umweltwissenschaften an der Universität Bremen

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Salmonella as a tumour medication

HZI researchers developed a bacterial strain that can be used in cancer therapy

Salmonellae are dangerous pathogens that enter the body via contaminated food and can cause severe infections. But these bacteria are also known to target...

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

3rd Symposium on Driving Simulation

23.10.2017 | Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

 
Latest News

Microfluidics probe 'cholesterol' of the oil industry

23.10.2017 | Life Sciences

Gamma rays will reach beyond the limits of light

23.10.2017 | Physics and Astronomy

The end of pneumonia? New vaccine offers hope

23.10.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>