Maare der Vulkaneifel
These further changed their appearance over many millennia. After completing the volcanic activity, the maar funnel was finally filled with refractory and volcanically ejected material that slid off the tuff walls into the maar crater. A maar lake emerged whenever there was enough groundwater at this level. The "eyes of the Eifel" ´were formed. Some of these marshes silted up again, others stayed dry from start on. Today, there are over 70 (scientifically proven) maars in the Vulkaneifel. Twelve of these are filled with water.