The dry maar is located on a hillside and belongs to the Quaternary volcanoes of the West Eifel. It is surrounded by a crater rim of between 36 and 120 metres high. From the analysis of volcanic tuffs, which were ejected from the maar during an eruption, and from geomagnetic measurements, five tuff fields and four volcanic centres on the edge of the bowl were identified. In the centre of the maar an eruption site was identified, hence the maar is probably an eruption funnel. The tuffs of the Dreiser Weiher lies above the depositions of the surrounding volcanoes, the maar is thus younger than the others. An exact date for the formation of the maars using pollen analysis could not be done for the Dreiser Weiher since there is no bog here.
So-called olivinite bombs, from the time when the maar was formed, occur in the vicinity. Due to the many, mainly rare minerals and rocks that occur here, the Dreiser Weiher achieved scientific renown early on. It is not clear whether the material here is from the Earth's mantle or whether it is due to magmatic differentiation. Discussions are still ongoing in scientific circles about the origin of the material.
