The Steffelnkopf cinder cone is underlain by a maar, as are most of the cinder cones in the West Eifel.
In the Volcano Garden it is possible to 'read' a physical record of the volcanic activity in the surrounding area. This began with the formation of the Laach Maar north of the Steffelnkopf, which is on a fault-line stretching from north to south, where Middle Buntsandstein to the east subsided relative to Lower Devonian rocks to the west. A complete profile of the maar tephra has been preserved below the Volcano Garden. And excellent 'antidune structures' are clearly evident. This volcanic activity was followed immediately, at the same weak spot, by the first maar period of the Steffelnkopf cinder cone. At this point, 'channel structures' appear in the physical record.
After this, there was a period during which there was no volcanic activity, and soil built up. Renewed volcanic activity began with a period during which a ring of tuff was built up around the Laach Maar. This was followed by cinder eruptions of the Steffelnkopf Volcano. During this last phase, the former maar crater of the Steffelnkopf Volcano was filled with cinder and agglutinate. This is how the former mountain came into being.