Internationally renowned Eifel Laminated Sediment Archive started 25 years ago and can today look back on remarkable research achievements
30 December 2024
The Eifel Laminated Sediment Archive (ELSA) project of the Institute of Geosciences of Johannes Gutenberg University Mainz (JGU) was launched 25 years ago. Today it provides an internationally valuable geoarchive providing us with insights into climate, environment, volcanism, and human behavior in the distant past. ELSA was initiated by Professor Frank Sirocko in 1999 with the aim of accessing the geoscientific evidence preserved in the sediments of the Eifel maar lakes and dry maars. A maar is formed when rising volcanic magma heats an aquiferous rock layer, which pore water expands in an explosion ejecting the rocks over the point of contact. The resultant hole in the landscape can be more than hundred meters deep and get filled with ground water, forming a maar lake. Thanks to these maars, we can now look far back into bygone ages. "The layers of the sediments of the Eifel maars record the events that have happened over the last 130,000 years and remarkably even for every individual year," said Sirocko. This allows researchers to determine, for instance, how and at what rate the Earth's former warm periods came to an end – as it was in just a few years in the case of the most recent warm period.
ELSA – the Eifel Laminated Sediment Archive
When ELSA was first established, drilling samples had been taken only from three of the open maar lakes that still survive in the formerly volcanic Western Eifel region. None of the older, already infilled maars had been studied by means of drilling 25 years ago. "We now have 55 drilling samples, some of which extend to a depth of 150 meters, from the 68 maar structures in the Eifel," reported Professor Frank Sirocko.
Over its 25-year history, the researchers involved in the ELSA project have published numerous research papers. Furthermore, all collected data is openly accessible via the project website. One of the main aspects that Professor Frank Sirocko has been interested in – and has also touched upon in various book publications – is the arrival and disappearance of former warm periods. The determining factor in this is precipitation. "Europe is mainly under the influence of the North Atlantic. Every drop of rain that falls here originates from the North Atlantic and its bordering seas," explained Sirocko, while also pointing out that all major climatic changes correlate with alterations to rainfall, whereas – perhaps surprisingly – it is not temperature that plays the decisive role. Another significant aspect is the spread of forests as they completely alter the structure of landscapes, determine the migration of wild animals, and thus also the hunting patterns of humans.
Bioanalysis of ancient DNA for a better understanding of the past 40,000 years
The core samples taken from the maar sediments provide important information on the development of volcanism and vegetation. It is even possible to assign an individual sediment layer to a single year, one of the unique features of the ELSA samples. The pollen spores found in these samples show, for instance, what the vegetation was like while centimeter-thick layers of volcanic ash testify to the volcanic eruptions in the Eifel region. With the help of the sediments of just five maars, it is possible to continuously reconstruct events in the area over the past 130,000 years.
"The data that we obtain from the Eifel region is not simply representative of that region alone but also applies to the developments in the whole of Central Europe," stated Sirocko. It is important to him to not just consider climate and environmental changes in isolation but also to take into account their effects on human development. New research undertaken in future could contribute to this. The results of preliminary investigations have shown that biomarkers and ancient DNA retained in the Eifel drilling samples can help supply details of the prehistoric environment. In combination with archaeological and anthropological data, the annual layers of the drilling samples will direct our intention to new, innovative research questions: Which human species lived in Central Europe at what time? Did they hunt animals? What did they eat in general? "It is research into this that I would really like to get up and running over the next couple of months," added Sirocko. The geologist and climate researcher plans to retire from his routine activities at the Institute of Geosciences by the end of 2024. He will continue to conduct investigations in this field as JGU senior research professor.