Featured Research

from universities, journals, and other organizations

Glacial Pace Of Erosion Was Not So Slow, New Technique Shows

Date:
December 12, 2005
Source:
University of Michigan
Summary:
Glaciers, rivers and shifting tectonic plates have shaped mountains over millions of years, but earth scientists have struggled to understand the relative roles of these forces and the rates at which they work.

A Flood Glacier in the Boundary Ranges of the Coast Mountains, British Columbia.
Credit: Image courtesy of University of Michigan

Glaciers, rivers and shifting tectonic plates have shaped mountains over millions of years, but earth scientists have struggled to understand the relative roles of these forces and the rates at which they work.

Related Articles


Now, using a new technique, researchers at the University of Michigan, California Institute of Technology and Occidental College have documented how fast glaciers eroded the spectacular mountain topography of the Coast Mountains of British Columbia.

Their work is described in the Dec.9 issue of the journal Science.

U-M assistant professor of geological sciences Todd Ehlers has been working in a remote region of the Coast Mountains for the past three years, studying rates of glacial erosion and topographic change. Using a new geochemical tool developed by the Caltech researchers, he and his collaborators were able to quantify the rates and magnitude of glacial erosion across a major valley. They found that glaciers radically altered the landscape around 1.8 million years ago, about the time that Earth began to experience a number of ice ages.

The erosion rates documented in the study suggest that glaciers eroded the mountains six times faster than rivers and landslides had before glaciation began. The researchers also found that glaciers scraped at least 2 kilometers (about 1.2 miles) of rock from the mountains.

"These results are exciting," Ehlers said, "because they clearly document that glaciers are the most efficient method for sculpting the topography of the range. They also demonstrate the utility of a new geochemical tool that can be applied to study erosion in other mountain ranges."

The study relied on a technique called helium-helium thermochronometry, developed by Caltech's Ken Farley and his former student David Shuster, now at Berkeley Geochronology Center in Berkeley, California. "It's an unwieldy name, but it gives us a new way to study the rate at which rocks approached Earth's surface in the past," Shuster said.

The new technique rests on three facts: one, that rocks on the surface have often come from beneath the surface; two, that the ground gets steadily warmer as depth increases; and three, that helium leaks out of a warm rock faster than a cold one. By determining how fast the helium leaked out of a rock, it's also possible to determine how fast the rock cooled and, ultimately, how deeply it was buried, as well as when and how fast it got uncovered.

The team showed that the cooling of the rock happened very quickly and that the entire valley was carved out in about 300,000 years.

"We can say that the glacier was ripping out a huge amount of material and dumping it into the ocean," Farley said. "And rather than taking evidence from a single instant, we can for the first time see an integral of hundreds of thousands of years. So this is a new way to get at the rate at which glaciers do their work."

Why the intense erosion occurred 1.8 million years ago is not `well understood, Shuster said, "but it seems to coincide with some very interesting changes that took place in Earth's climate system at that time."

In addition to Ehlers, Farley and Shuster, Margaret Rusmore, a geology professor at Occidental College in Los Angeles, was a coauthor on the paper. The research was supported by grants from the National Science Foundation.


Story Source:

The above story is based on materials provided by University of Michigan. Note: Materials may be edited for content and length.


Cite This Page:

University of Michigan. "Glacial Pace Of Erosion Was Not So Slow, New Technique Shows." ScienceDaily. ScienceDaily, 12 December 2005. <www.sciencedaily.com/releases/2005/12/051211220547.htm>.
University of Michigan. (2005, December 12). Glacial Pace Of Erosion Was Not So Slow, New Technique Shows. ScienceDaily. Retrieved January 29, 2015 from www.sciencedaily.com/releases/2005/12/051211220547.htm
University of Michigan. "Glacial Pace Of Erosion Was Not So Slow, New Technique Shows." ScienceDaily. www.sciencedaily.com/releases/2005/12/051211220547.htm (accessed January 29, 2015).

Share This


More From ScienceDaily



More Earth & Climate News

Thursday, January 29, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Scientists Say Earliest Snakes Lived Alongside The Dinosaurs

Scientists Say Earliest Snakes Lived Alongside The Dinosaurs

Newsy (Jan. 28, 2015) — Wrongly categorized as lizard fossils, snake fossils now show the reptile could have developed earlier than we thought — 70 million years earlier. Video provided by Newsy
Powered by NewsLook.com
Time Lapse: Sculptures Created from 30 Tons of Snow

Time Lapse: Sculptures Created from 30 Tons of Snow

Rumble (Jan. 28, 2015) — Students in North Finland use 30 tons of snow and one ton of ice to build a massive photography display and sculpture installation. Five days of work condensed into a one-minute time lapse! Video provided by Rumble
Powered by NewsLook.com
Aquaponics Turn Suburban Industrial Park Into Farmland: Hume

Aquaponics Turn Suburban Industrial Park Into Farmland: Hume

The Toronto Star (Jan. 27, 2015) — Ancient techniques of growing greens with fish and water are well ahead of Toronto bylaws. Video provided by The Toronto Star
Powered by NewsLook.com
Madagascar Locust Plague Could Mean Famine For Millions

Madagascar Locust Plague Could Mean Famine For Millions

Newsy (Jan. 27, 2015) — The Food and Agriculture Organization says millions could face famine in Madagascar without more funding to finish locust eradication efforts. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins