Featured Research

from universities, journals, and other organizations

Scientists Find Fossil Proof Of Egypt's Ancient Climate

Date:
February 18, 2005
Source:
Washington University In St. Louis
Summary:
Earth and planetary scientists at Washington University in St. Louis are studying snail fossils to understand the climate of northern Africa 130,000 years ago. While that might sound a bit like relying on wooly bear caterpillars to predict the severity of winter, the snails actually reveal clues about the climate and environment of western Egypt, lo those many years ago.

Earth and Planetary Sciences graduate student Johanna Kieniewicz (left) holds 130,000 year-old snail fossils from an Egyptian lake while Jennifer R. Smith, Ph.D., assistant professor of earth and planetary sciences in Arts & Sciences, examines leaf impression in tufa, a spring carbonate rock found at the same site. The researchers are trying to infer the Egyptian climate from the fossil evidence.
Credit: Photo David Kilper / WUSTL Photo

Feb. 2, 2005 — Earth and planetary scientists at Washington University in St. Louis are studying snail fossils to understand the climate of northern Africa 130,000 years ago.

Related Articles


While that might sound a bit like relying on wooly bear caterpillars to predict the severity of winter, the snails actually reveal clues about the climate and environment of western Egypt, lo those many years ago. They also could shed light on the possible role weather and climate played in the dispersal of humans "out of Africa" and into Europe and Asia. Periods of substantially increased rainfall compared to the present are known to have occurred in the Sahara throughout the last million years, but their duration, intensity, and frequency remain somewhat unconstrained.

Jennifer R. Smith, Ph.D., Washington University assistant professor of earth and planetary sciences in Arts & Sciences, and her doctoral student Johanna M. Kieniewicz, are using stable isotope and minor element analyses of the freshwater gastropod Melanoides tuberculata and carbonate silts from a small lake (now dry) in the Kharga Oasis of western Egypt to reconstruct climatic conditions during the lifetime of the lake. Their analyses support a surprising picture of arid Egypt: 130,000 years ago, what everyone considers an eternal desert was actually a thriving savannah, complete with humans, rhinos, giraffes and other wild life.

Evidence for the hominin presence abounds near the lake in the form of Middle Stone Age artifacts such as stone scrapers and blades.

"The artifacts provide a record that people were coming to the lake," said Smith. "Genetic evidence suggests that 100,000 to 400,000 years ago was a critical time in the evolution and dispersal of African hominins. Our climate data from this 130,000-year-old humid event suggest that this would have been a particularly good time for a northward migration through Africa following reliable water resources, since it seems to be the strongest humid phase in this region over the past 400,000 years. We're also testing the hypothesis that humid events were more frequent than previously thought, which would have allowed for greater mobility throughout the region."

The researchers noted that the silt thickness at the lake exceeds five yards, an indication that the humid phase lasted at least several thousand years. Normal rainfall in the area they study is a minuscule 0.7 of a millimeter per year, but there is evidence that the rainfall amounts in the region have gotten up to as much as 600 millimeters per year, "not enough to make it a paradise," Smith said, "but enough to turn a barren environment into a classic savannah."

Kieniewicz performed isotopic analyses of about 20 snails, all of them dating to the humid phase, which occurred approximately 130,000 years ago. These particular snails have a life span of between one and two years, and build their shells in a classic spiral with whatever water is available that day. The snails were preserved in calcium carbonate deposits throughout the lake.

"We're using the chemistry of the water over the course of a year or two, as revealed by isotopic analyses and minor element analyses of the snail shells to determine information about the climate then," Kieniewicz said. "The shell is an archive of the snail's life. The analyses give us snapshots of what the conditions were like in that lake basin."

The geochemical analyses confirmed that the water was a stable standing body for many years. "Strong evaporation of the lake, enough to shrink it substantially in volume and make it more saline would have been expected to result in large excursions in δ18O and minor element concentrations," Kieniewicz said. "However, throughout the stratigraphy, the δ18O values of the silts remain isotopically light and the minor elements do not show intense evaporative trends, suggesting that the lake remained stable and fresh."

Smith and Kieniewicz attended the 116th annual meeting of the Geological Society of America, held Nov. 7-10 in Denver. Kieniewicz presented a paper there on their findings.

Smith's specialty is geoarchaeology, which uses classic earth science methods and concepts to address questions of archaeological interest.

"In this particular study, we're interested in building a history of climate change through time to understand how people would have responded to dramatic shifts in climate," said Smith. "This is a major theme of our work, and we hope that some of our findings can give us perspective on what we're facing in the coming centuries."


Story Source:

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


Cite This Page:

Washington University In St. Louis. "Scientists Find Fossil Proof Of Egypt's Ancient Climate." ScienceDaily. ScienceDaily, 18 February 2005. <www.sciencedaily.com/releases/2005/02/050212191855.htm>.
Washington University In St. Louis. (2005, February 18). Scientists Find Fossil Proof Of Egypt's Ancient Climate. ScienceDaily. Retrieved November 26, 2014 from www.sciencedaily.com/releases/2005/02/050212191855.htm
Washington University In St. Louis. "Scientists Find Fossil Proof Of Egypt's Ancient Climate." ScienceDaily. www.sciencedaily.com/releases/2005/02/050212191855.htm (accessed November 26, 2014).

Share This


More From ScienceDaily



More Fossils & Ruins News

Wednesday, November 26, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Classic Hollywood Memorabilia Goes Under the Hammer

Classic Hollywood Memorabilia Goes Under the Hammer

Reuters - Entertainment Video Online (Nov. 26, 2014) The iconic piano from "Casablanca" and the Cowardly Lion suit from "The Wizard of Oz" fetch millions at auction. Sara Hemrajani reports. Video provided by Reuters
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
Ruins Thought To Be Port Actually Buried Greek City

Ruins Thought To Be Port Actually Buried Greek City

Newsy (Nov. 24, 2014) Media is calling it an "underwater Pompeii." Researchers have found ruins off the coast of Delos. Video provided by Newsy
Powered by NewsLook.com
Amphipolis Tomb Architraves Reveal Faces

Amphipolis Tomb Architraves Reveal Faces

AFP (Nov. 22, 2014) Faces in an area of mosaics is the latest find by archaeologists at a recently discovered tomb dating back to fourth century BC and the time of Alexander the Great in Greece. Duration: 01:05 Video provided by AFP
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