At 10,900 years old, the Ulmen maar is the youngest volcano in Germany. If you consider the entire history of the earth as a period of 24 hours, only a moment has passed since red-hot magma rose up here from a depth of around 60 kilometers. What initially makes its way slowly and sluggishly suddenly becomes highly explosive! As soon as the magma from the earth's interior hits the groundwater, extremely violent explosions occur in which the water suddenly vaporizes.
The extreme pressure waves from these explosions shatter the surrounding rock, which is ejected along the explosion vent and piles up a ring-shaped wall of volcanic loose rock (tephra) on the surface.
The layers of rock above collapse into the cavity blasted open at depth, creating the typical maar funnel. When the situation calms down, the crater begins to fill with precipitation and groundwater. A maar lake forms. A characteristic feature of maars is that they are always hollow shapes sunk into the land surface. Beyond the church, a few metres away from here, the layers of rock ejected during the eruption are clearly visible.
