ELEMENTI GEOLOGICI SULLA NECROPOLI ENEOLITICA DELLA SELVICCIOLA (ISCHIA DI CASTRO - VITERBO)

Abstract

Geological elements on the Eneolitic necropoli of Selvicciola (Ischia di Castro - Viterbo). The Eneolitic necropoli of Selvicciola (middle of
the IV millenium - end of the III millenium a.C.) is located at about 7 km SW Ischia di Castro (Viterbo) on the left side of Fosso
Strozzavolpe. The study of the area, still continuing, is aimed at the definition of geo-morphological features of the environment at the
time of establishment of the necropoli and of interaction between thermal springs present in the area and anthropogenic activity. The
tombs of the necropoli have been dug under a travertine cover, that acted as a roof, and is part of the very extensive travertine plate of
Canino, of an age ranging between Middle Pleistocene and Holocene and in places still precipitating. The Pleistocene volcanic substrate containing the tombs is strongly pedogenized and cut by an irregular erosion surface, occurring in the whole area of Canino, dated between Upper Pleistocene and Holocene. The study of stratigraphic sections allowed the recognition of calcareous organic silty levels in the basal part of the travertine cover, whereas in the uppermost portion, affected by karstic cavities, a blackish-brown organic soil occurs. Radiocarbon datings of the above-mentioned organic levels and soil (respectively Cal BP 13180-11860 and Cal BP 2956-2774) suggest that the travertine began to deposit towards the end of Lateglacial, before the establishment of the necropoli, and carried on until the late Holocene, until its abandonment. The facies analysis of travertine suggests that at the beginning the deposition environment could be fluvial to paludal. During the attendance of the necropoli the environment could be characterized by the occurrence of still active isolated springs, forming small running water resurgences and pools, likely utilized and controlled by human activity, as in other adjoining localities has been observed. The uppermost layers of the travertine cover, moreover, are affected by karstification, connected to a new erosion phase that caused the watertable lowering, the strong deepening of the hydrographic network and the dissection of the travertine cover and the substrate, as well as to pedogenetic processes that gave rise to the brown organic soil.