Bolzano quartz

280 to 260 million years ago, hot ash and lava was thrown out as a result of violent eruptions following major volcanic events. In this way a mighty mountain range was created on the North African continental plate – the Bozen quartz porphyry plate. At that time, the porphyry zone was located near the equator. Nowadays, Bozen quartz porphyry – reddish grey to dark grey in colour – forms the basis of the Bletterbach gorge.

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