The outstanding scenery of the Dolomites surrounding Cortina, which is unique in the world, is the result of complex geological events. It all began 235 million years (Ma) ago in a warm tropical sea dotted with atolls and lagoons, where marine sedimentation occurred during a period of 165 Ma. It was favoured by the slow, parallel dropping of the sea-bed, followed by powerful global tectonic movements which led to the uplifting of the Alps, about 25 Ma ago.
Two periods of the geological history mentioned above are highly significant for the Ampezzo valley:
The shallow waters of the Triassic, which alternated with the cliffs, were characterized by soft rocks, like marl and marl limestone: the so called “San Cassiano Formation” (229 Ma – Carnic), where extremely well preserved fauna fossils are found; this layer outcrops abundantly in several parts of the valley, The San Cassiano fossil collection, named after Rinaldo Zardini, is housed in the Palaeontological Museum of the Regole d'Ampezzo and it is one of the most important and most studied in the world.
Subsequently, a drop in the sea level and the emergence of vast land areas drastically altered the Dolomite landscape: the coral reefs disappeared and extensively flat sea-beds were formed. The shallow waters favoured the growth of large bivalves, as well as the appearance of the first land reptiles. The discovery, not only of animal fossil, but also of coal and amber testifies to the existence of luxuriant forests of resinous plants on islands of a lagoon system (“Travenanzes Formation”). In the amber drops found at the foot of Tofana, some mites – among the oldest ever studied in the world – and different species of pollen were discovered.