Gröden sandstone

Towards the end of the Palaeozoic era, the quartz porphyry was deeply eroded in places by the hot dry climate. From this, and even older eroded rubble, Gröden sandstone was formed. The 160 m thick formation in the Bletterbach consists mainly of coarse to fine river sediment, which was deposited in wide coastal plains.
A special feature is a calcarenite bank by the waterfall, the famous cephalopod bank, evidence of a short-term ingression by the sea. On the basis of the many reptile tracks, plant remains, and sediment structures found in the sandstone, it was possible to reconstruct accurately, and in detail, the landscape, and the flora and fauna which lived in it. In the 16th century a number of mining galleries were excavated in the lowest levels of the Gröden sandstone, in order to extract copper ore. The mining was not particularly successful, however.