The Holocene Ulmen maar


Aerial view of Ulmen Maar

Aerial view of Ulmen Maar with preserved tephra ring (background) and highly eroded Jungferweiher maar (foreground).

Geological Period

Quaternary / Holocene

Main geological interest



Vulkaneifel Geopark, Rhineland-Palatinate, Germany.
50°12’37.0″N, 6°58’58.0″E

Aerial view of Ulmen Maar with preserved tephra ring (background) and highly eroded Jungferweiher maar (foreground).

Youngest volcano in Central Europe, situated in Vulkaneifel, the volcanic region where the model of formation of maars by phreatomagmatic eruptions was established.

The IUGS Geological Heritage Site Ulmen Maar represents a key site for four geologically important processes that are of international relevance: (1) The maar allows introduction into the youngest volcanic activity in Central Europe. (2) It clearly shows the consequences of multiple explosive magma-water-interactions leading to phreatomagmatic eruptions. (3) The Ulmen maar is part of a maar-rich volcanic field. Here, essential arguments for the formation of maar volcanoes were developed. (4) Its postvolcanic crater lake presents a paramount insight into lake sediments and their interpretation with respect to the local weather and the climate during the maar’s lake history.

Tephra outcrop in the tunnel connecting the Ulmen and Jungferweiher Maar.

The 11,000 years old Ulmen Maar is Central Europe’s youngest volcano. Its maximum crater diameter is 470 m; its depth is 72 m including the 39 m deep crater lake. The 30 m thick tephra ring consists of ash and block-bearing lapilli-tuffs, which display characteristic features of explosive magma water interaction and phreatomagmatic eruptions. The magma involved had a hauyne melilite nephelinite composition.

The Ulmen Maar was formed in the youngest southeastern part of the West Eifel volcanic field. An amazing number of maars have formed here. 80 of the total 260 eruption centers in the West Eifel consist of maar volcanoes. Most of them are concentrated in the northwestern part (mainly old) and in the southeastern part (mainly young) of the volcanic field, where there is not very much groundwater. In the central part there are many scoria cones with an initial maar phase. Just north of the Ulmen Maar the 136,000 old Jungferweiher maar has a diameter of 2000 m and a depth of only 30 m. Its crater contains most of the altered and eroded debris of its catchment area. A 140 m deep drill hole gives evidence of the climate evolution during the past 119,000 years.

Scientific research on maar volcanism has been carried out by numerous international researchers for more than 200 years. The young and old crater topography of the Ulmen and Jungferweiher maars and their lake sediments serve as records of the youngest volcanism in the West Eifel and indicate where future volcanism might occur.

Volcanological map of the West Eifel Volcanic Field.

Büchel, G. (1993) ‘Maars of the Westeifel, Germany’, in J.F.W. Negendank and B. Zolitschka (eds) Paleolimnology of European Maar Lakes. Berlin, Heidelberg: Springer (Lecture Notes in Earth Sciences, 49), pp. 1–13. Available at:

Büchel, G., Lorenz, V. and Weiler, H. (1984) ‘Das Westeifel-Vulkanfeld: Maare, Schlackenkegel und Hydrogeologie (Exkursion H am 26. und 27. April 1984)’, Jahresberichte und Mitteilungen des Oberrheinischen Geologischen Vereins, pp. 107–128. Available at:

Lange, T. et al. (2019) ‘Neue Aspekte zum Vulkanismus der Westeifel) (Exkursion K am 26. April 2019)’, Jahresberichte und Mitteilungen des Oberrheinischen Geologischen Vereins, pp. 227–250. Available at:

Lange, T. and Büchel, G. (2022) ‘Zeitliche Abfolge der vulkanischen Ereignisse im SE-Teil des Vulkanfeldes der Westeifel während des Weichsel-Glazials’, Jahresberichte und Mitteilungen des Oberrheinischen Geologischen Vereins, pp. 313–365. Available at:

Lorenz, V. (1986) ‘On the growth of maars and diatremes and its relevance to the formation of tuff rings’, Bulletin of Volcanology, 48(5), pp. 265–274. Available at:

Steininger, J. (1820) Die erloschenen Vulkane in der Eifel und am Niederrheine: Ein Bericht an die Gesellschaft nützlicher Forschungen zu Trier. –  2; 82. Kupferberg. Available at:

Andreas Schüller
Naturpark und UNESCO Global Geopark Vulkaneifel

Georg Büchel
Universität of Jena, Institute of Geosciences

Volker Lorenz
Universität of Würzburg, Institute of Geography and Geosciences