The WEVF has more than 250 volcanic structures, most of which are basanitic scoria cones that reach about 100 m height with a basal diameter of about 600 m. 68 structures are from phreatomagmatic explosions at subsurface depth, which caused deep craters that collapsed and were finally filled with ground water, the so-called maar lakes. These lake basins serve as traps for sediment and were filled on average with 1 mm of sediment per year. Accordingly, a 100 m lake fills up within 100,000 years on average and becomes dry land. Fallout from eruptions near the maar site lead to deposits of decimeter or even meter thickness in the lake sediments. More distant eruptions cause ash layers of several cm thickness. These features are usually directly visible in the cored sediments and have been sampled in all ELSA cores. Mineral grains of the tephra show a distinct petrographic composition, which can be used as fingerprint to differentiate individual eruptions (Förster & Sirocko 2016), see chapter “Tephra” below. The age of the tephra layers is now updated with the ELSA-20 age model. The lake sediments thus provide a chronology for all eruptions in the WEVF during the lake phase, independent of any direct radiometric dating of the tephra. The resultant chronology for the west Eifel volcanisms has a precision of 150 years relative to the Greenland ice core chronology.
Most maar eruptions occurred during MIS5, MIS4, and MIS3. This resulted in a very large number of deep lakes during the entire time of MIS3, which was the time when modern humans started to inhabit central Europe. In total, we anticipated more than 50 lakes in the WEVF; accordingly, these lakes must have formed a most attractive region for the large herds of mammals and also for the humans, who hunted the glacial megafauna. It was most probable the highest number of open lakes during MIS3 in all of central Europe. Thus, the WEVF was a landscape with abundant lakes, which we call the “MIS3 Eifel Lake District”.