Role of slumped beds in the genesis and evolution of huge hypogean rooms: an example in the Valle del Nosê (Como, Northern Italy)

Abstract

During a detailed structural analysis of the cave systems of the Valle del Nosê (Como, Northern Italy), a systematic occurrence of thick (metric to decametric) slumped beds in several huge rooms and in other wide underground voids was observed. The systematic control, that these structures exert on the morphologies of the karst systems, suggests that slumped beds might play a major role in the genesis and evolution of large underground voids. In fact, thanks to their very high permeability, these beds seem to be able to act as the preferential way for water flowing in the very first phases of karst development, thus guiding cave development, while their mechanical properties, different from those of unslumped beds, make them prone to break down collapse, thus increasing the possibilities of the formation of huge rooms. On the basis of the observed field data, a genetic and evolutive model is therefore suggested to explain the origin of the largest voids in this area. This model has by now a strictly local effectiveness. © 2000 Éditions scientifiques et médicales Elsevier SAS