ELSA-20 is data file with annual resolution, which covers the last 60.000 years continuously with annual resolution. Four different sediment cores from Schalkenmehrener Maar Lake, Holzmaar Lake, and the infilled maar structure of Auel have been used to combine sections into a contious record. The most important part of ELSA-20 is the section before the Last Glacial maximum. This time interval from 25.000 – 60.000 y b2k (years before the year 2000) is documented continuously in two neighboring cores from the infilled maar of Auel. Gaps in one core were filled with a Dynamic Time Warp approach with sections from the other core.

One of the main problems with lake sediment drilling are drilling disturbances and gaps between individual core meters. To fill such gaps the ELSA-Project drilled two cores down to 100 m depth at a distance of only 5 m between cores. The two cores from Auel (AU3 and AU4) are offset with 0.5 m, thus gaps in one core can be closed with the respective section in the other core with a Dynamic Time Warp approach.

The resultant continuous organic carbon record reveals climate oscillations, which are well known from the Greenland ice, were the warm phases, called interstadials, have been dated precisely by annual layer counting of the ice(snow) layers (Rassmussen et al., 2014). The ages from the Greenland ice were applied to the respective sections of the ELSA-20 record to arrive at a stratigraphy fully comparable to the Greenland ice chronology.

The other parameter measured along with organic carbon was the Silicium and Aluminium content in the sediments. The ratio of these elements Si/Al is a proxy for the abundance of diatoms, which are the main producers of organic carbon in a lake system. The ELSA-20 data thus present an annual resolution, continuous time series for the abundance of diatoms in the lake. These algae are on maximum abundance only during warm intervals. The ELSA-20 is accordingly a time series of warm temperatures in central Europe, which have apparently exactly the same structure as the temperature changes in Greenland and thus the North Atlantic.

ELSA-20 is the first continuous paleoclimate record (spanning the entire last 60.000 years) from central Europe, and can be synchronized to the Greenland NGRIP ice core with decadal scale precision. The data are presented by Sirocko et al. 2021. The stratigraphy is the basis for all records presented on this website.