Featured Research

from universities, journals, and other organizations

Sea Level History Locked In Mississippi Mud

Date:
December 27, 2002
Source:
University Of Illinois At Chicago
Summary:
Rising sea levels and subsiding land are combining to gobble up more than two acres of the Mississippi Delta every hour. There is little dispute that this ecologically and economically important region — and more significantly, the future of metropolitan New Orleans — is under threat. What isn't clear, however, is how fast different parts of the delta are subsiding.

Rising sea levels and subsiding land are combining to gobble up more than two acres of the Mississippi Delta every hour. There is little dispute that this ecologically and economically important region — and more significantly, the future of metropolitan New Orleans — is under threat. What isn't clear, however, is how fast different parts of the delta are subsiding.

Related Articles


Previous studies of delta geological records from the past 8,000 years give a conflicting history. Some researchers find a pattern of a smooth, gradual rise in relative sea levels. Others indicate a step-like pattern suggesting long periods of stability, followed by dramatic elevations in sea level. But a new study led by Torbjörn Törnqvist, an assistant professor of earth and environmental sciences at the University of Illinois at Chicago, lends credence to the gradual rise hypothesis.

The evidence for Törnqvist's findings lies deep beneath the Mississippi Delta mud, or more precisely, in the peat that's packed beneath the muddy swamps.

"There's a lot of confusion about how sea level has changed in the delta over the last 7,000-8,000 years. Land loss is a potential problem in many coastal areas, but even more so in the Mississippi Delta because it is subsiding very rapidly," said Törnqvist.

For two summers, Törnqvist and his researchers took peat samples from 30 sites stretching between Baton Rouge and New Orleans, digging as deep as 12 meters to get the evidence they were looking for.

"Peat is organic matter. Plant material accumulates and is preserved in this wet environment. Peat contains remnants of plants that we can sieve out, like seeds or little pieces of wood. Some of these species are indicators of brackish water. If we find that, we know we must have been very close to sea level," he said.

Törnqvist's samples from different elevations in the eastern delta covered an area of about 20 square kilometers. The material collected was then carbon 14 dated using state-of-the-art accelerator mass spectrometry. Findings were plotted for sample age against depth below mean sea level.

"Our evidence shows that the natural pattern of sea level rise has been very smooth," said Törnqvist. The new data contradicts studies suggesting alternating long periods of stable sea levels, punctuated by short periods of extreme rises. The findings were reported in the Nov. 12 issue of Eos, the weekly newsletter of the American Geophysical Union.

Törnqvist's use of peat samples to read for geological clues is a first for the Mississippi delta region. He's excited about the technique.

"This is a perfect technique to see if there are variations in subsidence rates within the Mississippi Delta, or the entire coastal Louisiana," he said. "If that's the case, this will help enormously in making predictions of which areas are the most sensitive to wetland loss and coastal erosion. It may not be the same throughout all of coastal Louisiana. There's probably regional variation."

Törnqvist's Eos article was co-authored by UIC doctoral student Juan González, Lee Newsom of Pennsylvania State University, and Klaas van der Borg and Arie de Jong of Utrecht University in the Netherlands. The research was supported by a grant from the National Science Foundation.

Törnqvist's research team is presently collecting samples from the western Mississippi delta with the aim of finding peat that may yield relative sea level information about the past 3,000 years. Samples collected from the eastern delta region show the period from 3,000 to 8,000 years before the present.

"It's not that such samples don't exist in the eastern delta. There's probably loads of sites," said Törnqvist. "It's a logistical problem. Most of the areas we work in are surrounded by swamps," he explains. "They're just impossible to get into." The western delta study sites are more accessible.

Not that Törnqvist minds a bit of mud on his work boots. "Swamps are beautiful. I love to get into them," he said, "… when I'm in a boat."


Story Source:

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


Cite This Page:

University Of Illinois At Chicago. "Sea Level History Locked In Mississippi Mud." ScienceDaily. ScienceDaily, 27 December 2002. <www.sciencedaily.com/releases/2002/12/021227071704.htm>.
University Of Illinois At Chicago. (2002, December 27). Sea Level History Locked In Mississippi Mud. ScienceDaily. Retrieved November 27, 2014 from www.sciencedaily.com/releases/2002/12/021227071704.htm
University Of Illinois At Chicago. "Sea Level History Locked In Mississippi Mud." ScienceDaily. www.sciencedaily.com/releases/2002/12/021227071704.htm (accessed November 27, 2014).

Share This


More From ScienceDaily



More Earth & Climate News

Thursday, November 27, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Bolivian Recycling Initiative Turns Plastic Waste Into School Furniture

Bolivian Recycling Initiative Turns Plastic Waste Into School Furniture

Reuters - Innovations Video Online (Nov. 26, 2014) — Innovative recycling project in La Paz separates city waste and converts plastic garbage into school furniture made from 'plastiwood'. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
Blu-Ray Discs Getting Second Run As Solar Panels

Blu-Ray Discs Getting Second Run As Solar Panels

Newsy (Nov. 26, 2014) — Researchers at Northwestern University are repurposing Blu-ray movies for better solar panel technology thanks to the discs' internal structures. Video provided by Newsy
Powered by NewsLook.com
Antarctic Sea Ice Mystery Thickens... Literally

Antarctic Sea Ice Mystery Thickens... Literally

Newsy (Nov. 25, 2014) — Antarctic sea ice isn't only expanding, it's thicker than previously thought, and scientists aren't sure exactly why. Video provided by Newsy
Powered by NewsLook.com
3D Map of Antarctic Sea Ice to Shed Light on Climate Change

3D Map of Antarctic Sea Ice to Shed Light on Climate Change

Reuters - Innovations Video Online (Nov. 24, 2014) — A multinational group of scientists have released the first ever detailed, high-resolution 3-D maps of Antarctic sea ice. Using an underwater robot equipped with sonar, the researchers mapped the underside of a massive area of sea ice to gauge the impact of climate change. Ben Gruber 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