Aspects of the Evolution of an Important Geo-Ecosystem in the Lessinian Mountain (Venetian Prealps, Italy)

Povzetek

The Grotta dell’Arena (476 V/VR), located in the Lessinian Mountain, at the elevation of 1512 m a.s.l., is a very important underground karst system. Although it is only 74 m long, several of the geological, geomorphological and environmental features of the High Lessinian underground karst are present in this cave. The Grotta dell’Arena shares some common geological and faunistic characters with other important and well known karst systems. This cave has also one of the highest number of troglobitic species in all Venetian Prealps and some of them possibly originated in the pre-Quaternary. From the geological point of view the cave is the expression of a contact karst, where different limestone types come in contact both stratigraphically and along tectonic structures. The Grotta dell’Arena is located at the stratigraphic contact between the “Calcari del Gruppo di San Vigilio” and the “Rosso Ammonitico” and it is very close to a fault plane putting in vertical contact the two above formations with the “Biancone”, a kind of limestone closely stratified and densely fractured, very sensible to frost weathering. It is interesting to note the presence of a good number of species of Tertiary, or more generally pre-Quaternary, originate in the Grotta dell’Arena. This presence is possibly related to the geology of caves. In this paper the different kinds of underground karst systems in the Grottta dell’Arena and Lessinian Mountain, are analyzed and the relation with the cave fauna distribution are taken in consideration.