This area is also one of the symbols of the Dolomites both in scenic and geological terms. These mountains have been the object of scientific curiosity ever since the pioneer period of the first geologists and they still attract many researchers and scientists. Despite the fact that the area is crossed by important faults in a varying NS to NW-SE directions, the original relationships between the different bodies and the stratigraphic continuity of the principal elements are perfectly preserved from a structural point of view. In fact, the original margins and slopes of the preand post-volcanic platforms have been conserved. The successions outcropping in the eastern area are prevalently represented by Late Ladinian volcaniclastic sandstones, which cover the slopes of the previous Ladinian platforms of the Sciliar Dolomite and above which the basin sedimentation of the post-volcanic Cassian platforms can be observed once more (S. Cassiano Formation and Cassiana Dm). Moving westward we can also observe the successive elements of the stratigraphic series such as the Santa Croce/Heiligkreuz Formation, the Travenanzes Formation and the Dolomia Principale; the youngest formations on the other hand (Calcare di Dachstein and Calcari Grigi) characterise the highest peaks of the Mount Pelmo massif. The interval of time documented in this system runs from the Late Permian to the Early Jurassic with a truly remarkable continuity. The tectonic structure of the area can be traced back to a compressive phase oriented in an ENE-WSW direction known as “Valsuganese”. This unfolds in a series of SE-vergent overthrusts which, at the top, give rise to an alternating of synclines and anticlines. The Monte Pelmo massif is characterised by a synclinal structure which continues north with an anticline (Anticline of the Col de la Puina) and then it form a “cuesta” structure at Formin-Croda da Lago-Rocchetta group.
Stratigraphic and paleontological emergencies
– From a stratigraphic point of view, a complete succession (more than 2.5 km thick) has been preserved from the Late Permian to the Early Jurassic, bearing witness to an interval of time spanning approximately 100 million years.
– The response of the carbonate and terrigenous systems to the sea level variations during the Anisian period are perfectly documented here by the repetition of three superimposed sub-aerial erosion systems, continental conglomerates, lagoons and recovery of the bioconstructed platforms. The interaction of the platform-basin systems of the Serla Superiore and Contrin with the respective basin sediments are emphasised here by the preservation of the margins and paleo-slopes with respect to the basins and therefore by the possibility of analysing in detail the tectonic and eustatic control on the platforms themselves.
– The Sciliar platform, is three dimensionally preserved in all its parts, showing back-stepping geometries of the margins and the progressive sinking of the atoll under the photic zone related to the increase in subsidence during an important transgression. The drowning of the platform is documented by the red ammonites and encrinites on the top of the lagoon and on the slopes, and by the reduction of exportation of carbonate into the basins.
– The relationships between the drowned carbonate buildups (guyot) and the terrigenous and volcanoclastic deposits of the Late Ladinian are amazing. The onlap geometries between these and the paleo-slope are among the most spectacular of all the Dolomites.
– The interfingering of the Cassian Dolomite with the San Cassiano Formation at the Gusela del Nuvolau is impressive.
– The basin sequences, at the toe of the slope or those linked to the condensation on the top of the drowned platform, are rich in fossiliferous localities known for over 200 years. The most important examples include Punta Zonia which has provided splendid examples of ammonoids from the Late Anisian and Ladinian, those of the Cernera area, the Dont and Recoaro Formations, of the Val Fiorentina; the Carnian examples from the San Cassiano Formation of Gusela del Nuvolau or Forcella Giau.
– As regards the ichnofauna, reptile footprints have been documented from all continental terrigeneous units of the Anisian period, moreover the peritidal dolomites of the Cassian Dolomite and the base of the Dolomia Principale have provided important findings of fossilized dinosaur tracks, including those from the landslide block at the base of the Pelmetto which have revolutionised the knowledge of the paleogeographical structure of the area.