Aspetti morfologici ed evolutivi delle cavità endoglaciali di origine criocarsica

Morphological and evolutive features of criokarstic endoglacial caves

Abstract

In the last 10 years Italian cavers performed many researches in endoglacial caves, both on Alpine and extra-European glaciers. Here we give a first description of results. The explorations were made mainly into epiglacial inflow ice-shafts, named moulins, to study their morphology and hydrodynamic. On the other side a numerical model was developed to understand the evolution of drainage conduits. The ice-shafts develop essentially on glacier plains, huge and with few crevasses, the morfological are very similar to the karstic rock ones and they have to be considered pseudo-karstic or cryokarstic caves. At depth between 70 and 150 m it is possible to attain to the surface of the water-table. Observations suggest the existence of a complex structured phreatic network; its level varies up to some meters, depending upon the water flow and the plastic deformation of cavities. Numerical models show that the absorbed waters flow trough a treelike network of conduits at depth around 100-150 m, the network appairs to be «planished» on the glacier acquifer surface. Models and direct observation show that during winter, when runoff disappears, the conduit network collapses at depth lower than 50-60, pushing the resident water up to 10-20 meters under the glaciers surface.