Petrified water.
Text: Angelika Jacobs
Thousands of years compacted into just a few centimeters of rock: stalagmites contain a valuable climate record that stretches back farther than tree rings or ice cores.
Professor Dominik Fleitmann and his team collect samples from dripstone caves in various regions of the world, including the Middle East and North Africa, as well as in Switzerland. In the Milandre Cave in the Canton of Jura, the researchers have been measuring the drip rate and temperature for a number of years in order to incorporate this measurement data into their analyses.
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In consultation with the relevant authorities and associations, the researchers remove a core from one of the selected stalagmites. In the case of formations with a smaller diameter, it makes sense for them to take the entire stalagmite away with them. (Photo: University of Basel, Christian Flierl)link.zoom -
Good equipment is invaluable, as the cave expeditions are a muddy affair. The carefully packaged core then travels back to the laboratory with the team. (Photo: University of Basel, Christian Flierl)link.zoom -
Inside the boxes lie petrified climate records from all over the world. Some of the stalagmites in Fleitmann’s collection contain layers that are several million years old. (Photo: University of Basel, Christian Flierl)link.zoom -
At regular intervals, the researchers extract samples for chemical analysis. The thickness and composition of the layers reflect the environmental conditions in which they were formed. (Photo: University of Basel, Christian Flierl)link.zoom -
A mass spectrometer provides details of the geochemical fingerprint of the rock samples and also allows precise dating using radioactive elements. Changes that took place in the local climate hundreds of millennia ago can therefore be pinpointed to a period of about a dozen years. (Photo: University of Basel, Christian Flierl)link.zoom -
With their trained eyes, the geologists can read the history of this stalagmite from the patterns in its layers. The scratches, incisions and holes bear witness to their intensive research work on this specimen from Yemen. (Photo: University of Basel, Christian Flierl)link.zoom
The actual focus of their research, however, is on the interior of the stalagmites. By examining the layered deposits, they can reconstruct how precipitation and temperature levels have varied over the millennia. Like tree rings, these layers of what Fleitmann calls “petrified water” reflect the climatic and weather conditions at the time. In the future, he also wants to scour the deposits for traces of genetic material, which allows conclusions to be drawn about the community of soil organisms in the ground above the cave. This, he says, will offer additional insights into the prevailing environmental conditions.
Fleitmann is also fascinated by the influence of climate variations on the twists and turns of the past from a social and political perspective. With this in mind, he combines his data with archaeological finds and historical records. What influence did climate variations have on the emergence of the Silk Road or Islam, for example? And was there a historical precedent for the biblical Flood?
Dominik Fleitmann has been Professor of Quaternary Geology since 2019 at the Department of Environmental Sciences, where he plans to establish a center for research into speleothems (the technical term for cave formations).
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