GEOLOGICAL AND PALAEONTOLOGICAL ASPECTS

The Bernadia Mountains massif presents geological aspects of remarkable importance and fascination. The Eastern part of the massif, where there is the Vigant-Pre Oreak, is basically constituted by two rocky units: the paleocenic and oceanic flysch as well as the carbonatic limestone platform of the Cretaceous. The Vigant cave starts from the carbonatic limestone platforms near their passage to flysch and the complex is entirely developed inside limestones that initially follow the direction of the stratification. The development of the complex seems to be scarcely influenced by the presence of tectonic disturbances even if the entry of the Pre-Oreak Cave finds itself on a little fault. The limestones of the Eastern part of Bernadia Mountains where the Vigant-Pre Oreak can be found, were formed at the Northern edge of the Friulian Carbonatic Limestone during the inferior Cretaceous and are to be referred to the formation of the Cellina Limestones. The flysch is basically an alternance of more or less thin strata of sands and marls or clays that originated from deep sea basins at the edges of areas that emerged in the initial phases of an orogenesis. The Grivò Flysch is a flyschoidal succession that formed itself between the ancient Palaeocene and the inferior Eocene (57-50 million years ago) and reaches a thickness of 1500 metres. From the paleontologic point of view, along the Cornappo torrent, near the entry of the Pre-Oreak Cave emerge black limestone thinly stratified and stinky when beaten (they smell like hydrocarbon) that formed because of a scarce water circulation and remixing with a consequent hypoxia and establishment of unfavourable life conditions that are however favourable to fossilization. These strata, that can be referred to the Barremian (125-130 million years ago), provided numerous fossils of particular scientific value. Mainly fishes, among whose there are the oval body shapes that nourish themselves of hard-shelled (Picnodontiforms) invertebrates as well as little specimens strictly related to current sardines and anchovies that belong to the widespread group of Clupeiforms. Relatively numerous are also the shellfishes; more rare are the impressions of jellyfishes and vegetal remains. Near Vigant emerges one of the Grivò Flysch megabeds: at its base there is a big block of whitish cretaceous limestone (therefore more ancient than the Flysch) that is extremely rich of fossils. The most eye-catching and common remains are the peculiar rudistae shells. Finally, inside the Vigant Cave were found the bone remains of mammals that were populating the area during the last glaciation (Würmian glaciation 120.000-11.000 years ago) together with those that lived subsequently. In particular, Ursus spelaeus, Gulo gulo, Vulpes vulpes, Meles meles, Voles, chiropterans and other micro-vertebrates are to be mentioned./p>

Galleria aspetti geologici e paleontologici Calcarei Ingresso grotta Flysch Bacino Giulio