Most of the Eifel maar structures are old Pleistocene lakes from the last glacial cycle, and have been filled up completely with sediment. Today, these structures are well visible in the landscape, often surrounded by a forested tuff wall and with grassland or swamps in the center. Some of these infilled maar lakes were fed with debris from soil erosion in the catchment, which is particularly large if a creek runs through the basin. For the ELSA-20 we have chosen only maar structures, which were indeed filled with fluvial runoff. The cores from Auel, thus, have the highest sedimentation rate of up to 5 mm/yr during cold and wet phases of MIS3. The sedimentation rate during the warmer interstadials is, in contrast, only around 1 mm/yr. A disadvantage of Auel is the observations that the lake during peak glacial times had a lowered lake level by several meters. The lake water depth from 22,000 – 15,000 yr b2k was thus only a few meters, which implies that waves and currents could have disturbed the sedimentation patterns.
ELSA-20 uses the Auel sediment also for the last glacial maximum, but in addition we study cores from nearby Dehner Maar, which has no creek inlet and a very small catchment (Sirocko et al. 2016). This maar is thus infilled by eolian dust only, and we use it for specific work on the dust fraction. Römer et al. (2016, 2019) determined the provenance of dust and differentiated the long range transport from the local deflation with analysis of the heavy-minerals. The Dehner Maar record is counted for glacial varves at the moment and it will be used to study the aridity history on an indeed varve counted annual basis.