The Rodderberg is a geological rarity. At 13,000 years old, it is the youngest volcano in Western Europe.
The area was declared a nature reserve in 1927 to preserve the characteristic dry grasslands with special plant and animal species that occur on the volcanic tufa surfaces. Well-marked hiking trails lead through this interesting area. There are excellent views of the Siebengebirge and the Rhine Valley from everywhere.
Extensively cultivated semi-dry calcareous grasslands grow on the raw soils of the hilltop and the Aschenwall, and patchy, sometimes lichen-rich sedum pioneer communities and sand pioneer grasslands grow in small former tufa pits.