Inside the Earth, huge amounts of hot magma are under great pressure and are being pushed towards the surface.
Anyone who wants to learn more about tuff can easily find out about this rock and its uses in the 'Weiberner Schaufenster' ('Weibern Shop Window').
The history of the Mayener Grubenfeld begins with the eruption of the Bellerberg Volcano about 200,000 years ago.
Clay and sand particles float around gently and settle on top of each other in layers on the seabed. But this tranquillity comes to an abrupt end.
A volcano erupts. Hot drops of lava are thrown out of the vent and fall onto other fragments of lava which have been spewed out during earlier eruptions.