In the locality of Rocchi, on the Vicentine Monti Lessini, below a superficial covering of detritus, a lens constituted by a clay of volcanic ash was discovered. This contained fossilised tree trunks still preserved in their original positions to a depth of least two metres; they seem to have bee substituted by silico-carbonaceous material, which has only partly preserved the structure of the wood. The vulcanoclastic lens rests on carbonaceous rocks which here make up the deposits on the internal lagoon of a vast active depositional system, between the eastern Monti Lessini and the Monti Berici, in the lower Oligocene period. This depositional system of Caribbean type, in which the Calcareniti of Castelgomberto are deposited, was active thanks to the presence of a coral reef, which today emerges along the south eastern edge of the Berici.

However, the site of Castelgomberto seems to fall within the series of geological events, of the upper Oligocene, which determined the end due to its emergence of the berico-lessinea carbonaceous platform; the emerged area was then elaborated by karstik phenomena and effected by basaltic volcanic activity of subaerial type, before the new marine encroachment dating to the lower Miocene. However, due to the lack of outcrops, this series of geological events, although of great importance from a stratigraphic point of view, is only sketchily understood. (MiBAC)