Featured Research

from universities, journals, and other organizations

Crater Chain On Two Continents Points To Impact From Fragmented Comet

Date:
March 17, 1998
Source:
University Of Chicago
Summary:
A team of scientists working on two continents has discovered that a series of five craters on Europe and North America form a chain, indicating the breakup and subsequent impact of a comet or asteroid that collided with Earth approximately 214 million years ago.

214 million year-old event corresponds with mass extinction

Related Articles


A team of scientists working on two continents has discovered that a series of five craters on Europe and North America form a chain, indicating the breakup and subsequent impact of a comet or asteroid that collided with Earth approximately 214 million years ago.

The impacts may have contributed to a mass extinction that occurred at the end of the Triassic period–one of the five greatest mass extinctions in history.

The work, by scientists at the University of Chicago, the University of New Brunswick (Canada) and The Open University (Milton Keynes, U.K.) is published in a paper in the Thursday, March 12, issue of the journal Nature.

“When scientists observed the impacts of the pieces of Comet Shoemaker-Levy 9 on Jupiter in July 1994, they said that the impact of a fragmented comet could never happen here on Earth because the Earth’s gravitational field is too weak to break a comet into pieces,” said David Rowley, University of Chicago Associate Professor in Geophysical Sciences. “But our studies of these five craters provide compelling evidence that this happened at least once, and there’s no reason it couldn’t have happened more than that.”

Rowley’s colleagues, John Spray, a structural geologist from the University of New Brunswick, and Simon Kelley from The Open University, were interested in the relationship between impact craters of similar ages. Kelley had developed a technique to date such craters more precisely–using laser argon/argon dating of the glass formed by localized heating of the rock. They asked Rowley to help figure out how the craters were aligned when the impacts occurred–because of plate tectonics, the continents have moved extensively in the last 214 million years.

Rowley, a principal investigator for the University of Chicago’s Paleogeographic Atlas Project, which is compiling an atlas of the paleogeography and paleoclimate of the world as it changed over the past 500 million years, had that kind of information at his fingertips.

“I get these kinds of requests all the time,” said Rowley, “so at first I didn’t think about it too much. But when they asked to me take a closer look at the data and I saw the alignment, I just said, ‘wow!’”

Three of the five craters, Rochechouart in France, and Manicouagan and Saint Martin in Canada, were at the same latitude–22.8 degrees–forming a nearly 5000-kilometer chain. The other two, Obolon’ in Ukraine and Red Wing in Minnesota, lay on identical declination paths with Rochechouart and Saint Martin, respectively. All of the craters are previously known and well-studied, but the paleoalignment has never before been shown.

One possible explanation for the alignments of the five craters is a fragmented comet that crashed to Earth in three major groups over a period of time as short as four hours, in two groups of two and one solitary chunk. It is possible that the comet or asteroid actually broke into more than five pieces, but most of the Earth at that latitude was ocean 214 million years ago, and evidence of any ocean-bottom craters has long been obliterated. The impacts may have occurred over a period of several days, depending on how widely the fragments were dispersed.

Rowley said that the chance that these craters are randomly aligned is near zero.

Manicouagan, the largest of the five craters, is more than 100 kilometers in diameter, comparable to the 170-kilometer Chixulub crater in the Yucatan–the impact that is believed to have caused the mass extinction at the end of the Cretaceous period 65 million years ago, killing the dinosaurs.

The Triassic extinction was equivalent in magnitude to the Cretacious/Tertiary (K/T) extinction: about 80% of the species then living on the planet became extinct.

There are 150 known impact craters worldwide; the group is now studying others to see if there are other coincident crater chains.

The Paleogeographic Atlas Project at the University of Chicago is compiling an atlas of the world’s changing geography and climate. The data are used for testing climate change models, finding probable sites for oil and minerals, and for providing a comprehensive look at the evolution of Earth’s geographic features. The work is funded by a constortium of companies that has included Amoco, Exxon, Mobile, Total, Elf-Aquitaine and Shell, British Petroleum, Conoco and Marathon. More information can be found at http://plates.uchicago.edu/.


Story Source:

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


Cite This Page:

University Of Chicago. "Crater Chain On Two Continents Points To Impact From Fragmented Comet." ScienceDaily. ScienceDaily, 17 March 1998. <www.sciencedaily.com/releases/1998/03/980317070410.htm>.
University Of Chicago. (1998, March 17). Crater Chain On Two Continents Points To Impact From Fragmented Comet. ScienceDaily. Retrieved March 1, 2015 from www.sciencedaily.com/releases/1998/03/980317070410.htm
University Of Chicago. "Crater Chain On Two Continents Points To Impact From Fragmented Comet." ScienceDaily. www.sciencedaily.com/releases/1998/03/980317070410.htm (accessed March 1, 2015).

Share This


More From ScienceDaily



More Earth & Climate News

Sunday, March 1, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Whale-Watching Scientists Spot Baby Orca

Whale-Watching Scientists Spot Baby Orca

AP (Feb. 28, 2015) Researchers following endangered killer whales spotted a baby orca off the coast of Washington state, the third birth documented this winter but still leaving the population dangerously low. (Feb. 28) Video provided by AP
Powered by NewsLook.com
Bridge Collapses Due to Flooding in Bolivia

Bridge Collapses Due to Flooding in Bolivia

Reuters - News Video Online (Feb. 28, 2015) Heavy rain and flooding sweep through parts of Bolivia causing damage and leaves more than 2,000 people homeless. Sophia Soo reports. Video provided by Reuters
Powered by NewsLook.com
Death Toll from Afghan Avalanches Tops 200

Death Toll from Afghan Avalanches Tops 200

AFP (Feb. 27, 2015) More than 200 people have been killed in a series of avalanches triggered by heavy snowfall in Afghanistan. Duration: 00:42 Video provided by AFP
Powered by NewsLook.com
France, Philippines Call for Agreement on Climate Change

France, Philippines Call for Agreement on Climate Change

Reuters - News Video Online (Feb. 27, 2015) The presidents of France and the Philippines issue a joint appeal for a binding agreement on climate change. Katie Sargent reports. Video provided by Reuters
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