10. Muddy lagoons, or tidal plains

Some 217-199 million years ago – the Norian/Rhaetian era

The entire Dolomite region became a vast muddy plain, regularly encroached on by the sea. The general sinking of the area caused by subsidence resumed, making room for the slow accumulation of enormous piles of sediment on this tidal plain.

The Dolomite region became a vast plain covered in mud and sand, located at sea level. This plain underwent cyclical exposure to the open air and became covered in a carpet of algae and bacteria. At other times, when the sea invaded, what was now the ocean floor, inhabited by giant molluscs, was predominantly muddy. The rate at which these sediments accumulated was similar to the region’s general rate of sinking through subsidence. After several million years, this process resulted in incredibly thick layers of sediment, in some places over 1000 metres. Towards the end of this period, the rate of sinking changed and in some areas the environment became deeper, less oxygenated sea.

Text by Dolomiti Project

Some rocks and fossils from this era