The Alpiner Verrucano

The mainly red, partly green, grey or brown sediments of the Alpiner Verrucano and the overlying Alpiner Buntsandstein are not restricted to small basins like the earlier sediments. On the contrary, they can be found from northern Germany to Poland down to Italy. They were deposited in the same way under the same conditions as the underlying older sediments, although the climate was more humid. Therefore the transportation distance was longer and the debris, consisting mostly of resistant quartz, became well rounded and smaller. At that time, the Earth’s crust also broke open in this region and intensive volcanic activity started. Remnants of lava flows can be found in the sandstones as very finely grained green layers. Such volcanic flows and pipes are well known from Bartholomaeberg as they are the host rocks of ores like gold, silver, copper or iron. In some parts uranium or barite can be found as well. They are the source of the ore deposits that were mined starting from the middle of the Bronze Age, about 1500 BC. At the time of deposition vegetation was more well- developed, due in part to the finely grained sediments that offered living space for worms whose burrows can still be found.

The reason that the rocks are predominantly red is because the colour red is the result of various processes of erosion, oxidation or rust formation from iron in the deposits and proves that there was a prevailing hot climate with occasional rainfalls at the time that this deposit built up enabling the formation of rust.