The maar blasted into the so-called ribbon slate tier! This is a transitional layer between the Lower Devonian Siegen- and Unterems tier. Here it is covered by maar tuffs at the surface. The maar cone was formed in an Üßbach tributary valley and originally had a size of 600 x 700 m with a depth of 60 m at the Devon top edge. Particularities Just as several other maars in the Eifel (Meerfeld maar, Eichholz maar), the maar lake was drained in 1750 by deepening the stream ravine and used for agriculture. The maar soil was significantly more fertile than the surrounding rocky slate soil lacking minerals. During World War I, between 1914 and 1918, nobody maintained the drainage, allowing a shallow maar lake to form again until today! The maar lake now only has one drainage, but no inlet! Water is only added by rainfall, surface and groundwater!