The volcano complex lies in the East Eifel between the villages of Ettringen and Kottenheim and the town of Mayen on the edge of a fault zone of the Middle Rhine Basin. Violent movements caused disturbances in the bedrock, so that, along this fault, magma rose from a chamber at a depth of 10-20 km. Volcanic activity began approximately 200,000 years ago in the eastern part of the Bellerberg Volcano. Gaseous, 1,100 °C hot magma reached the earth's surface at several eruption centres and formed smaller cinder cones. Huge quantities of lava fragments, which were thrown mainly in an easterly direction, formed the cinder ridge of the Kottenheimer Büden. Gradually, a crescent-shaped crater wall formed, which probably grew to more than 20 m high within a few days. In addition, longer fissures appeared, which produced large quantities of lava and thus gave rise to the Ettringer Bellerberg.