Submarine volcanic activity enriched water with silica (SiO2), allowing organisms with siliceous skeleton (such as radiolaria and sponges) to thrive. Their remains got mixed up with the calcareous mud at the bottom of the deep basins and were later dissolved by the waters circulating into the forming rock. Yet the dissolved silica remained inside the rock, eventually concentrating as chert nodules in the limestone.

This natural asset is part of the tour "Browsing through the rocks of the Secëda mountain".

Severe erosion of rocks by streams and rivers creates gravel and pebbles that are rounded off by the swirling water. These coarse clastic deposits can also go through a natural cementation process to form a conglomerate. The different colours of the debris indicate a wide source area featuring many different types of rock. 

This natural asset is part of the tour "Browsing through the rocks of the Secëda mountain".

This large bivalve mollusc ruled the mud flats of the largest Triassic carbonate platform, for good reason called Dolomia Principale (Main Dolomite), stretched throughout the Dolomites and over a good part of the western Tethys. The dolomitization process almost always dissolved its thick shell, leaving only the sediment that filled the shell itself. 

The recovery of coral reefs reached a first peak 235 million years ago, and the specimens found around Cortina are an excellent example of this. The extraordinarily well-preserved ecosystem of corals, sponges and molluscs is a unique paleontological feature of the Dolomites, testifying to an apex in marine biodiversity across the whole Mesozoic era. 

These large gastropods were ornamented with spines or tubercles, partly to reinforce their shells and partly to be able to hide in amongst the gravel right at the contact with the rough waters, where this association used to live. The organisms were then transported into deeper waters forming the deposits we now call 'Pachycardia Tuff'. 

These spherical snails could grow to a considerable size and were able to remain stable on powerful waves thanks to their smooth surface. We can imagine these molluscs were brightly coloured, as a few specimens reveal traces of colour, even if we do not know yet which colour they were. 

This bivalve mollusc makes up 90 percent of the fossils in the Pachycardia Tuff layers, which explains where they got their name from! These layers of coarse sediments (sandstone and conglomerates with rounded gravel of volcanic origin) are only found on Alpe di Siusi and represent deposits containing organisms that lived on the beaches of the volcanic islands, where the waves were very strong. Pachycardia has a very thick shell that made it resistant to the force of water.

Palm trees were missing on the volcanic islands of the Triassic atolls, as they were not to turn up until over 100 million years later! Yet there were palmlike trees that were related to primitive plants today represented by the ginkgo or sago cycad. Pterophyllum belongs to the now-extinct Benettitales, which populated the coasts in the Triassic period along with primitive conifers and ferns. Palm trees would not have been a feature of these beaches! 

Nowadays, coral reefs are one of the most spectacular environments thanks to the beauty, shape and colour of its organisms. This ecosystem finally managed to recover during the Late Ladinian period, after a big crisis following the mass extinction. The large coral colonies found in abundance on the Alpe di Siusi plateau bear witness to this significant biological event. 

Daonella are typical bivalve molluscs from the Middle Triassic period (247-237 million years). Their thin, flat shells were reinforced with radiating ribs that, beside their circular to sub-triangular shell outline, characterize the species. Daonella lommeli is one of the largest and most widespread species. As it is often found in rocks deposited in the open sea, it is presumed that it lived afloat the water thanks to its thin, wide shell.