Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists find fossil proof of Egypt’s ancient climate

09.02.2005


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. David Kilper / WUSTL Photo


’At a snail’s pace’

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. 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 ä18O and minor element concentrations," Kieniewicz said. "However, throughout the stratigraphy, the ä18O 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."

Tony Fitzpatrick | EurekAlert!
Further information:
http://www.wustl.edu

More articles from Earth Sciences:

nachricht GPM sees deadly tornadic storms moving through US Southeast
01.12.2016 | NASA/Goddard Space Flight Center

nachricht Cyclic change within magma reservoirs significantly affects the explosivity of volcanic eruptions
30.11.2016 | Johannes Gutenberg-Universität Mainz

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>