To enable visitors to better understand the various eras and habitats in which the fossils took shape, inside the museum an ideal route has been created with descriptions, photographs and drawings of the typical rock formations that enveloped these ancient living creatures.
The panel alongside represents the time spiral relating to the evolution of our planet and life on Earth.
The section indicating a period between 234 and 65 million years ago highlights the 169 million years during which the layers of rock today found in the Ampezzo basin and surrounding areas were deposited.
These rock strata contain numerous fossils, traces of the incredibly prolific and diversified life forms that characterised this period in our region. Most of these fossils are "Triassic", meaning the fossils of animals and plants that lived in the early period of the area shown in green: the Triassic.
During that period, the Dolomites were more or less located at the tropics (15-20° latitude north), on the western edge of a large marine gulf that penetrated into the supercontinent called Pangaea.
This sea, called Tethys, was warm, clear and suitable for the growth of reefs separated by straits, some deep, others less so, similar to those that today distinguish the Maldive Islands, the Caribbean and the Great Barrier Reef in Australia.
About 234 million years ago, at the end of the Anisian stage, in the area of Mount Cernera, to the south of the Ampezzo basin, there was an atoll surrounded by a sea that became increasingly deeper in the direction of Cortina. Various types of fossils have been found in these rocks that point to different environments: the ammonites, animals that lived in the deep sea around the atoll and the organisms that created the atoll itself (algae, brachiopods, large and small bivalves, gastropods and sea anemones).
The discovery of ammonites is of great scientific interest: because these are animals that evolve in different and unique forms, it has in fact been possible to precisely reconstruct a geological time scale for that period.
So far as the organisms that created the atoll are concerned, their presence and subsequent disappearance would seem to point to the atoll, after an initial growth stage, having slowly and gradually sunk.
230 million years ago, during the upper Ladinian stage, in the parts of the sea located to the west and south of the Cortina d'Ampezzo basin, volcanic eruptions occurred with the formation of islands. Following the erosion of these islands, dark deposits were produced called “volcanoclastics”.
In these rocks, besides marine organisms (lamellibranchia and ammonites), important plant fossil remains have been found indicating that tropical forests grew on the lands above sea level.
229 million years ago, at the beginning of the Karnian stage, when volcanic activity had ceased, in the Cortina d'Ampezzo basin and surrounding areas, a relatively deep (300 –500 m) tropical sea environment was recreated, dotted with coral reefs just below the surface of the water.
In this tropical sea, reconstructed in a simplified manner in the picture at the bottom of the corridor to the left, calcareous mud and deposits of various types built up, including algae, single corals, shells (lamellibranchia, gastropods, cephalopods, brachiopods), sea urchins (Echinoids) and sea anemones (crinoids). These deposits, which subsequently produced “soft” rocks like Marnes and marly limestone, are today known by the name of San Cassiano Formation.
225 million years ago, during the Karnian stage, the dolomite landscape was heading towards a drastic change caused by a drop in sea level with the consequent emergence of large land areas, especially towards the south of the Ampezzo basin.
The coral reefs had disappeared once and for all. Flat and extensive sea-beds were taking shape, covered by very shallow water (just a few inches), generally murky due to the movement of the waves. The nearby dry land was covered with forests. The sediments that deposited in these environments often contain: fossils of large bivalves (Trigonodus, Myoforia, Pachycardia, Ostrea); sometimes the fossilised teeth of fish and rarely the bones of land reptiles; the remains of plants, mainly conifers and equiseta, often found in the form of coal and drops of fossil resin: amber.
This amber is among the oldest in the world. In most cases, the drops are small in size – from just a few millimetres to a few centimetres. Many are cracked due to the strong pressure of the fossilisation process. Some even contain microscopic inclusions such as pollen, ash and vegetable fragments.
224 million years ago, during the Norian stage, a general increase in sea level resulted in land areas being periodically covered by the sea (tidal plains), as is the case today of a number of islands belonging to the Bahamas archipelago. In this environment, simplified in the picture on the right, the Main Dolomite deposits began to form. A typical feature of Main Dolomite is its cyclic nature, which can be seen by observing the rock faces. These consist of very regular strata, indicative of events that occur cyclically. By carefully observing each single stratum, we can see that these, in turn, consist of two parts: one is densely laminated and corresponds to carpets of fossilised algae, the other is thicker and consists of calcareous mud transformed into rock which contains the internal models of bivalves, the megalodonts. The cycle was repeated dozens and dozens of times due to a lucky concurrence of circumstances, among which a slow, but continuous lowering of the sea-bed (subsidence). By offsetting the depositing of mud and the growth of the carpets of algae, this resulted in the water remaining shallow throughout the region.
The repetition of these cycles for about ten million years produced an accumulation of 1000 metres of deposits that today form the magnificent rock faces around Cortina d'Ampezzo.
210 milioni di anni fa, alla fine del periodo Triassico, un veloce abbassamento del fondo marino porta l'intera regione da condizioni di piana di marea (Dolomia Principale) a un bassofondo tropicale sempre coperto dall'acqua e simile all'attuale piattaforma sommersa delle Isole Bahamas. Anche il clima cambia: si passa infatti da un clima tropicale arido influenzato dalla vicinanza della terra emersa, ad un clima tropicale umido, tipicamente marino. Nelle parti interne della piattaforma, caratterizzate da acque calme, si depositavano i fanghi carbonatici. Le parti esterne della piattaforma, prospicienti il mare aperto e soggette all'azione diretta del moto ondoso, presentavano condizioni favorevoli alla formazione di dune sabbiose sottomarine. Inoltre la presenza di acque limpide, agitate e ricche di nutrimento permetteva l'insediarsi di vari organismi tra cui numerose colonie di brachiopodi. Tutti e tre questi depositi, trasformati successivamente in rocce calcaree, costituiscono oggi la successione del Calcare di Dachstein, dei Calcari Grigi e dell'Encrinite di Fanes.
About 185 million years ago, in the mid-Jurassic period, the platform of limestone deposits suddenly dropped even further below the sea due to the sea-bed falling to over 1000 metres. It thus became a plateau swept by ocean currents that did not permit the accumulation of deposits of any substantial thickness. In this environment lived large molluscs with spiral-shaped shells similar to the “Nautilus” and now extinct: the Ammonites. Due to the discovery of numerous fossil shells of these animals and to the red colour of these deposits, they have been called Ammonite red
Between 131 and 65 million years ago, during the Cretaceous period, various sediments were deposited that have been grouped together under the name of Marne of Puez. These are friable and easily eroded rocks that produce rounded-hill shapes now visible on the mountain plateaux.
Such deposits accumulated in a deep-sea environment. They prevalently consist of microscopic shells of plankton and numerous ammonite shells showing a genetic mutation in the shape of the spiral, that tends to unwind and open.
They also contain fine particles of clay and silt, as wells as sand-grain pebbles pointing to the arrival of detritus from the erosion of the first mountains of the Alpine Chain that was already forming underneath the sea.
These are the youngest rocks of the Dolomites and date back about 25 million years, to the Tertiary period. They consist of rounded pebbles of various nature and size, mixed with sands and the remains of shells, algae and sharks’ teeth, and are called Mount Parei Conglomerate.
The environment in which these rocks took shape can be imagined as a rather rough coastline with steep cliffs soaring high above the sea, interrupted by small valleys down which torrents carried detritus to the sea, creating new sections of beach. The Mount Parei Conglomerate was deposited horizontally at the mouth of valleys and on the sea-bed and consists of vertical strata. These vertical strata indicate both the deformation of the rocks in a period before the conglomerate was deposited and the beginning of the great upheavals that resulted in the creation of the Dolomites.