The ELSA Project was initiated by Frank Sirocko in 1998, shortly after he was appointed as Professor for Geoscience at the Johannes Gutenberg-University Mainz, which is located in Germany in the state of “Rheinland-Pfalz”. The most important, and at that time already well studied geoarchive in this state were the open maar lakes with Holocene sediment infill in the West Eifel Volcanic Field. The older, already infilled maar lakes, however, were not studied at all with any drillings up to that time. The challenge was to drill through many meters of young gravel into the underlying fine grained lake sediments and date their age. The first 20 drillings down to 10 m depth were done with a Rammkern system, the subsequent 50 drillings (see table under Core Locations) with a commercial Seilkern technique by the drilling company “Stölben Bohr”. All drillings were dated with 14C ages, which revealed that almost all infilled maar structures are from the last glacial cycle except two older, the Walsdorfer (MIS6/7) and the Döttinger (MIS11/12) infilled maars. 23 large maar structures were chosen for deep scientific drilling down to 100 m, the Jungferweiher infilled maar even down to 160 m.

Freeze core SMfreeze from Schalkenmehrener Maar

Dating techniques evolved with drilling experience; 9 different dating methods were applied to date all cores (Sirocko et al. 2005, 2013, 2016, 2021). About 20% of all drill cores from the Eifel maars reveal annual layers, called varves. Unfortunately, continuous varve formation is only observed in the Holocene and some older interstadials, glacial sections and stadials are often only laminated; i.e. layered, but not with annual resolution. The countable annual sediment layers are the unique quality of the ELSA sediments. 

The subsequent years explored the possibility of annual layer (varve) counting and systematic core to core correlations with pollen and tephra analysis. The pollen represent the vegetation around the maar and allow to determine the history of the landscape, well reproducible from one site to the other. Eruption from the Eifel volcanism lead to distinct cm-thick tephra layers in the lake sediments, which can be correlated between cores by their petrographic composition. The dates for the eruptions are derived from the dated lake sediment. Volcanic eruptions and regional vegetation change showed a consistent pattern, which resulted in the definition of Landscape Evolution Zones (LEZ), which Sirocko et al. (2016) used to determine environmentally uniform phases during the last 60,000 years.

The four best dated sediment cores from the maar lakes of Schalkenmehren and Holzmaar were combined with the longest records from older infilled maar lakes of Dehner and Auel; all of which combined to a continuous time series of annual resolution, which cover the last 60,000 years continuously, the so-called ELSA-20 record (Sirocko et al. 2021). The ELSA-20 data can be downloaded directly from this website, the NATURE-GEOSCIENCE website and the PANGAEA website.

It is the intention of this ELSA Project website to present all data, which have been analyzed during the last two decades on the new ELSA-20. This chronology is within 150 years comparable to the annual layer counted Greenland ice core GICC05 chronology. Thus, ELSA-20 provides the unique possibility to synchronize the climate and environment of central Europe with the global ice core chronologies.

The ELSA core archive

References, nomenclature and data download

This ELSA Project website presents the background information for all ELSA cores. It now concentrates on the ELSA-20 record, but will finally present the core photos and data for alle ELSA data produced during the last 20 years. References are made only to published peer reviewed scientific papers of the ELSA Project itself. Some figures are taken from published papers, but reduced to basic findings, others use the original proxy data, but all time series plot on the new ELSA-20 stratigraphy. More detailed scientific information is accessible from the referenced papers directly; see a list of all peer reviewed ELSA papers at the end of this text. Respective data can be directly downloaded from the home page of this website, all figures shown can be downloaded in Powerpoint format. All ages of this text and figures are presented as “yr b2k” (years before the year 2000), which is the official nomenclature of the Greenland ice core GICC05 chronology. The text includes several other stratigraphic abbreviations, which are “MIS” for “Marine Isotope Stage”, “GI” for “Greenland interstadial”, “LGM” for Last Glacial Maximum.