The Rodderberg is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

volcano A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most oft ...

in the east of the municipality of

Wachtberg Wachtberg is a municipality in the Rhein-Sieg district, of North Rhine-Westphalia, Germany. It is situated approximately 15 km south of Bonn Bonn () is a federal city in the German state of North Rhine-Westphalia, located on the banks o ...

near

Bonn Bonn () is a federal city in the German state of North Rhine-Westphalia, located on the banks of the Rhine. With a population exceeding 300,000, it lies about south-southeast of Cologne, in the southernmost part of the Rhine-Ruhr region. This ...

, Germany. The last eruption was 250,000 years ago. It is situated just above the

Rhine The Rhine ( ) is one of the List of rivers of Europe, major rivers in Europe. The river begins in the Swiss canton of Graubünden in the southeastern Swiss Alps. It forms part of the Swiss-Liechtenstein border, then part of the Austria–Swit ...

valley. Together with the Drachenfels directly opposite, the Rodderberg narrows the Rhine valley. This gorge portion is the southern limit of the lowland-bay of Cologne. The Rodderberg offers views to the

Siebengebirge The (), occasionally Sieben Mountains or Seven Mountains, are a hill range of the German Central Uplands on the east bank of the Middle Rhine, southeast of Bonn. Description The area, located in the municipalities of Bad Honnef and Königswin ...

, the Rhine valley and up to the

Cologne Cathedral Cologne Cathedral (, , officially , English: Cathedral Church of Saint Peter) is a cathedral in Cologne, North Rhine-Westphalia belonging to the Catholic Church. It is the seat of the Archbishop of Cologne and of the administration of the Archd ...

, about 50 km away.

Geology

The Rodderberg detonated in a

phreatomagmatic eruption Phreatomagmatic eruptions are volcanic eruptions resulting from interaction between magma and water. They differ from exclusively magmatic eruptions and phreatic eruptions. Unlike phreatic eruptions, the products of phreatomagmatic eruptions cont ...

about 250,000 years ago. This happened when the magmatic plume reached the groundwater level of the Rhine (about 50 m higher than today). After the explosion, the crater was filled with water that formed a

maar A maar is a broad, low-relief volcanic crater caused by a phreatomagmatic eruption (an explosion which occurs when groundwater comes into contact with hot lava or magma). A maar characteristically fills with water to form a relatively shallow ...

of about 90 m depth. In the last 250,000 years this feature filled with dust and soil until it was filled up to today's level.Patrick Schläfli et al. (2023). New vegetation history reconstructions suggest a biostratigraphic assignment of the lowermost Rodderberg interglacial (Germany) to MIS 11. '' Quaternary Science Reviews'' 302: 107932 The Rodderberg is now a small hill that has a shallow concave shape.

References

{{coord, 50, 38, 33, N, 7, 11, 54, E, region:DE_type:mountain, display=title Landforms of North Rhine-Westphalia Landforms of Rhineland-Palatinate Volcanoes of Germany Maars of Germany Extinct volcanoes of Europe Pleistocene volcanoes Nature reserves in Rhineland-Palatinate