Featured Research

from universities, journals, and other organizations

The K-T Impact Extinctions: Dust Didn't Do It

Date:
January 24, 2002
Source:
Geological Society Of America
Summary:
Scientists basically agree that an asteroid struck the Earth some 65 million years ago and its impact created the Chicxulub crater in Yucatan, Mexico. More controversial is the link between this impact and a major mass extinction of species that happened at the geological (K-T) boundary marked by the impact.

Scientists basically agree that an asteroid struck the Earth some 65 million years ago and its impact created the Chicxulub crater in Yucatan, Mexico. More controversial is the link between this impact and a major mass extinction of species that happened at the geological (K-T) boundary marked by the impact.

Related Articles


But what mechanism did the impact trigger to cause mass extinction? The conventional theory is that impact dust obscured the sun, shutting down photosynthesis and snuffing out life. Kevin Pope from Geo Eco Arc Research shows in the February issue of GEOLOGY that the assumptions behind this theory are amiss, and therefore damage estimates from future asteroid impacts are also amiss.

This latter point became a recent issue when a large asteroid passed near the Earth on January 7 and news reports exaggerated its potential impact effects.

“Based on the old, inaccurate dust numbers, which erroneously suggested that a medium-sized asteroid (1-2 km in diameter) could cause global climate change and famine, scientists calculated that one's chance of getting killed by an asteroid impact were about the same as dying in a plane crash,” Pope said. “My new impact dust estimates indicate that death by an asteroid is far less likely and that such medium-sized asteroid impacts would not have catastrophic global effects. But of course the regional effects would still be devastating.”

To truly understand the influence of impact dust, scientists need to find a way to directly measure the amount of small dust particles in such places as the K-T boundary. In the meantime, Pope studied patterns of coarse dust particles to create a model that showed how the small dust particles were dispersed. Incorporating these geological observations with new theoretical work, Pope asserts that very few of the particles are of the size that it would take to shut down photosynthesis for any significant length of time and therefore the original K-T impact extinction hypothesis is not valid. He believes it may have been sulfate aerosols produced from impacted rocks and soot from global fires that could have shut down photosynthesis and caused global cooling.

“The original studies of the clay layer found at the K-T boundary assumed much or all of this layer was derived from fine impact dust,” he said. “More recent studies of this layer have shown this not to be the case. Furthermore, earlier estimates were based on extrapolations of data from surface atomic bomb blasts, which had about 100 million times less energy than the Chicxulub impact. Extrapolation over eight orders of magnitude is risky business.”

Pope was involved in the “discovery” of the Chicxulub crater in 1989-1990 when he worked at the NASA Ames Research Center. (Oil geologists had discovered the crater and reported the finding in 1981, but it was basically ignored.) He was using satellite images to map water resources in the Yucatan with Adriana Ocampo and Charles Duller when they found the semi-circular ring of sink holes. They thought the crater might be the K-T impact site and published their hypothesis in the May 1991 issue of NATURE.


Story Source:

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


Cite This Page:

Geological Society Of America. "The K-T Impact Extinctions: Dust Didn't Do It." ScienceDaily. ScienceDaily, 24 January 2002. <www.sciencedaily.com/releases/2002/01/020124174127.htm>.
Geological Society Of America. (2002, January 24). The K-T Impact Extinctions: Dust Didn't Do It. ScienceDaily. Retrieved October 31, 2014 from www.sciencedaily.com/releases/2002/01/020124174127.htm
Geological Society Of America. "The K-T Impact Extinctions: Dust Didn't Do It." ScienceDaily. www.sciencedaily.com/releases/2002/01/020124174127.htm (accessed October 31, 2014).

Share This



More Earth & Climate News

Friday, October 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

How A Chorus Led Scientists To A New Frog Species

How A Chorus Led Scientists To A New Frog Species

Newsy (Oct. 30, 2014) A frog noticed by a conservationist on New York's Staten Island has been confirmed as a new species after extensive study and genetic testing. Video provided by Newsy
Powered by NewsLook.com
Raw: Hawaii Lava Approaching Village Road

Raw: Hawaii Lava Approaching Village Road

AP (Oct. 30, 2014) The lava flow on the Big Island of Hawaii was 225 yards from Pahoa Village Road on Wednesday night. The lava is slowing down but still approaching the village. (Oct. 30) Video provided by AP
Powered by NewsLook.com
Endangered Carpathian Ponies Are Making a Comeback in Poland

Endangered Carpathian Ponies Are Making a Comeback in Poland

AFP (Oct. 29, 2014) At the foot of the rugged Carpathian mountains near the Polish-Ukrainian border, ranchers and scientists are trying to protect the Carpathian pony, known as the Hucul in Polish. Duration: 02:17 Video provided by AFP
Powered by NewsLook.com
Deadly Mudslide in Sri Lanka Buries Houses

Deadly Mudslide in Sri Lanka Buries Houses

AP (Oct. 29, 2014) A mudslide triggered by monsoon rains buried scores of workers' houses at a tea plantation in central Sri Lanka on Wednesday, killing at least 10 people and leaving more than 250 missing, an official said. (Oct. 29) Video provided by AP
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