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".

Gypsum rock layers originate in a natural salt flat, a very shallow marine environment in a warm, dry climate. Evaporation concentrates salts in sea water until they precipitate, starting with sulphates (gypsum is CaSO4, calcium sulphate). The white layers that can be seen from the Seceda cable car are precisely the remains of these natural salt flats. 

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

The sand that was formed due to the erosion of red porphyry could only be red. It covered a wide plain featuring rivers and lakes surrounded by vegetation and inhabited by primitive reptiles and amphibians at a time when the sea had not yet reached the Val Gardena area. After millions of years, the sand naturally hardened to become sandstone, a firm yet workable rock which may be carved. 

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

How often have you driven along a road paved with blocks of porphyry without realising that this rock was formed from the rapid cooling of lava! This mostly reddish volcanic rock in the Bolzano province makes up a thick bedrock which is the base of the sedimentary sequence. It can be seen along the motorway north of Bolzano or on the Resciesa ridge in Val Gardena. 

Ammonites can amaze us with their bizarrely shaped shells, which often came about close to the many great crises they suffered during the long 300-million-year life. Macroscaphites starts off as a normal ammonite rolled up in planispiral shape, then straightening out and ending with a hooklike bend. The planispiral, gas-filled part kept the shell stable in the water, while the organism itself lived in the hooklike section. 

Bellerophon, a planispiral snail, is one of the best-known fossils of the Dolomites: it lends the Bellerophon Formation its name and bears witness to the definitive arrival of the sea at the end of the Permian period. This exhibit shows the snail together with a large Tainoceras malsineri, ancestor of today's Nautilus cephalopod. The large number of microfossils (calcareous algae and foraminifers) testifies to the wide variety of life forms in existence shortly before the mass extinction.

Ammonites sometimes look very similar to each other thanks to their history spanning over 300 million years. They have a planispiral shell more or less marked with ridges and tubercles. Yet they can be classified also on the basis of inner characters, so that there is never a perfect repetition. As a result, this ammonite from the Cretaceous period may always be distinguished from its ancestors.

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.