5. A tropical archipelago is born

Some 246-238 million years ago – the Anisian era

The Dolomite region continued to sink into the sea while at the same time fragmenting due to tectonic stretching. In the Triassic Tethys Ocean there arose a new and unusual section of sea marked by islands eroded by rivers and atolls and barriers formed from living organisms.

During this period, the Dolomite region was subjected to tectonic stretching, a form of subsidence that transformed it into this new section of sea. This was no longer shallow with a flat sea floor, but its depth alternated between shallow and deep zones. The zones that rose higher from the bottom became the habitat for the first communities of marine wildlife such as algae, corals, sponges and sea urchins, capable of grouping together and giving rise to islands. These organisms therefore created the first archipelago of tropical atolls in the Dolomite region. At the same time sedimentation occurred between these islands, more typical of deeper marine environments. The increase in tectonic movements, together with the variations in the depth of the sea, caused the organic islands to emerge temporarily from the sea with consequent erosion of their exposed parts. Numerous reptiles wandered this exposed land, leaving traces of their passing.

Text by Dolomiti Project

Some rocks and fossils from this era