The Pulvermaar belongs to a group of volcanoes that begins a little to the south of here. Magma forces its way up through a vent and meets groundwater underground. Violent steam explosions tear up the overlying layers of bedrock. Rock collapsing back and breaking away creates a cone-shaped collapse - the Strohner Märchen. Soon afterwards, magma rises again at its north-western edge.
This time it does not hit groundwater, but is ejected as lava and piles up into a cone that is now 65 meters high - the Römerberg. The Strohner Märchen at the foot of the Römerberg gradually silts up and is now a raised bog with unique flora and fauna. The last link in the chain is the Pulvermaar. A new vent forms in the north-west and leads to the most powerful explosions of the volcanic group. Once again, magma meets water underground
and blows out a cavity. When the overlying layer of rock collapses, a crater is created that was once 200 meters deep. Gradually, the fractured rock of the crater rim slips away and settles on the extinct vent. Nevertheless, at 74 meters, the Pulvermaar is the deepest of all the Eifel lakes. Around the maar, you can see what the volcano once ejected: its 20-metre-thick wall of volcanic loose rock (tephra) is still almost completely preserved today and can be explored on a circular trail.
