Featured Research

from universities, journals, and other organizations

As Waters Clear, Scientists Seek To End A Muddy Debate

Date:
December 18, 2007
Source:
Indiana University
Summary:
Geologists have long thought muds will only settle when waters are quiet, but new research shows muds will accumulate even when currents move swiftly. This may seem a trifling matter at first, but understanding the deposition of mud could significantly impact a number of public and private endeavors, from harbor and canal engineering to oil reservoir management and fossil fuel prospecting.

IU Bloomington geologist Juergen Schieber inspects a moving mud formation at the base of a mud "race track."
Credit: Indiana University

Geologists have long thought muds will only settle when waters are quiet, but new research by Indiana University Bloomington and Massachusetts Institute of Technology geologists shows muds will accumulate even when currents move swiftly.

This may seem a trifling matter at first, but understanding the deposition of mud could significantly impact a number of public and private endeavors, from harbor and canal engineering to oil reservoir management and fossil fuel prospecting.

"Mudstones make up two-thirds of the sedimentary geological record," said IU Bloomington geologist Juergen Schieber, who led the study. "One thing we are very certain of is that our findings will influence how geologists and paleontologists reconstruct Earth's past."

Previously geologists had thought that constant, rapid water flow prevented mud's constituents -- silts and clays -- from coalescing and gathering at the bottoms of rivers, lakes and oceans. This has led to a bias, Schieber explains, that wherever mudstones are encountered in the sedimentary rock record, they are generally interpreted as quiet water deposits.

"But we suspected this did not have to be the case," Schieber said. "All you have to do is look around. After the creek on our university's campus floods, you can see ripples on the sidewalks once the waters have subsided. Closely examined, these ripples consist of mud. Sedimentary geologists have assumed up until now that only sand can form ripples and that mud particles are too small and settle too slowly to do the same thing. We just needed to demonstrate it that it can actually happen under controlled conditions."

Schieber and IU graduate student Kevin Thaisen used a specially designed "mud flume" to simulate mud deposition in natural flows. The oval-shaped apparatus resembles a race track. A motorized paddle belt keeps water moving in one direction at a pre-determined speed, say, 26 centimeters per second (about 0.6 miles per hour). The concentration of dispersed sediment, temperature, salinity, and a dozen other parameters can be controlled. M.I.T. veteran sedimentologist John Southard provided advice on the construction and operation of the mud flume used in the experiments.

For their experiments, the scientists used calcium montmorillonite and kaolinite, extremely fine clays that in dry form have the feel of facial powder. Most geologists would have predicted that these tiny mineral grains could not settle easily from rapidly moving water, but the flume experiments showed that mud was traveling on the bottom of the flume after a short time period. Experiments with natural lake muds showed the same results.

"We found that mud beds accumulate at flow velocities that are much higher than what anyone would have expected," said Schieber, who, because of the white color of the clay suspensions, calls this ongoing work the "sedimentology of milk."

The mud accumulates slowly at first, in the form of heart- or arrowhead-shaped ripples that point upstream. These ripples slowly move with the current while maintaining their overall shapes.

Understanding how and when muds deposit will aid engineers who build harbors and canals, Schieber says, by providing them with new information about the rates at which mud can accumulate from turbid waters. Taking into account local conditions, engineers can build waterways in a way that truly minimizes mud deposition by optimizing tidal and wave-driven water flow. Furthermore, Schieber explains, the knowledge that muds can deposit from moving waters could expand the possible places where oil companies prospect for oil and gas. Organic matter and muds are both sticky and are often found together.

"If anything, when organic matter is present in addition to mud, it enhances mud deposition from fast moving currents," he said.

The finding feels like something of a vindication, Schieber says. He and his colleagues have (genially) argued about whether muds could deposit from rapidly flowing water. Schieber had posited the possibility after noting an apparent oddity in the sedimentary rock record.

"In many ancient mudstones, you see not only deposition, but also erosion and rapid re-deposition of mud -- all in the same place," Schieber said. "The erosive features are at odds with the notion that the waters must have been still all or most of the time. We needed a better explanation."

Full research findings appear in the December 14 issue of Science. This research was supported by a grant from the National Science Foundation.


Story Source:

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


Cite This Page:

Indiana University. "As Waters Clear, Scientists Seek To End A Muddy Debate." ScienceDaily. ScienceDaily, 18 December 2007. <www.sciencedaily.com/releases/2007/12/071213152603.htm>.
Indiana University. (2007, December 18). As Waters Clear, Scientists Seek To End A Muddy Debate. ScienceDaily. Retrieved July 25, 2014 from www.sciencedaily.com/releases/2007/12/071213152603.htm
Indiana University. "As Waters Clear, Scientists Seek To End A Muddy Debate." ScienceDaily. www.sciencedaily.com/releases/2007/12/071213152603.htm (accessed July 25, 2014).

Share This




More Earth & Climate News

Friday, July 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Goma Cheese Brings Whiff of New Hope to DRC

Goma Cheese Brings Whiff of New Hope to DRC

Reuters - Business Video Online (July 24, 2014) The eastern region of the Democratic Republic of Congo, mainly known for conflict and instability, is an unlikely place for the production of fine cheese. But a farm in the village of Masisi, in North Kivu is slowly transforming perceptions of the area. Known simply as Goma cheese, the Congolese version of Dutch gouda has gained popularity through out the region. Ciara Sutton reports. Video provided by Reuters
Powered by NewsLook.com
Bill Gates: Health, Agriculture Key to Africa's Development

Bill Gates: Health, Agriculture Key to Africa's Development

AFP (July 24, 2014) Health and agriculture development are key if African countries are to overcome poverty and grow, US software billionaire Bill Gates said Thursday, as he received an honourary degree in Ethiopia. Duration: 00:36 Video provided by AFP
Powered by NewsLook.com
Higgins Breaks Record at Mt. Washington

Higgins Breaks Record at Mt. Washington

Driving Sports (July 24, 2014) Subaru Rally Team USA drivers David Higgins and Travis Pastrana face off against a global contingent of racers at the annual Mt. Washington Hillclimb in New Hampshire. Includes exclusive in-car footage from Higgins' record attempt. Video provided by Driving Sports
Powered by NewsLook.com
Storm Kills Three, Injures 20 at Virginia Campground

Storm Kills Three, Injures 20 at Virginia Campground

Reuters - US Online Video (July 24, 2014) A likely tornado tears through an eastern Virginia campground, killing three and injuring at least 20. Linda So 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:
from the past week

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