Relationships between soils and geomorphology in the Telesina Valley (Southern Italy): preliminary results

This paper depicts the first results of an integrated geomorphological and pedological study performed in the Telesina Valley (Campanian Apennines, Southern Italy), aimed to investigate the relationships between morphogenetical and pedological processes. The Telesina Valley is an asymmetric, E-W elongated morphostructural depression, in which the Calore River flows. On the northern side, the valley is bordered by steep, marly-calcarenitic slopes of Toppo Capomandro relief, cut in the “Flysch Rosso” Formation terrains (Upper Cretaceous-Miocene). The piedmont area of such relief is characterized by strongly remodeled remnants of a glacis; the latter is partly depositional and developed on the ancient foothill scree talus deposits, and partly erosional, being cut in arenaceous-pelitic terrains mainly belonging to the Caiazzo Unit (Upper Miocene). The age of the glacis is presumably Lower Pleistocene. The glacis area is characterized by severe erosional processes. The glacis is connected with the oldest of five orders of Calore River alluvial terraces. The bedrock of the four highest orders consists of polygenic and heterometric gravels with sandy interbeddings, of Middle Pleistocene in age, while the lowest order developed on silty-sand alluvial deposits (Holocene). The I order (Middle Pleistocene) has a depositional origin; the II order (Middle Pleistocene), the III order (Upper Pleistocene) and the IV order (Lower-?Middle Holocene) have erosional origin; and the V order (?Middle-Upper Holocene) is depositional. While the IV and V order are very well preserved, the oldest terraces are strongly eroded. On the southern side of the valley, only the IV and V order occur; they are partly buried by alluvial fan deposits consisting of carbonatic pebbles in a volcanoclastic matrix. Such deposits form the foothill scree talus of the Mt. Camposauro carbonatic massif, which borders the study area to the south. The pedological survey has been performed on the five orders of alluvial terraces and on the glacis area. Field description, bulk and micromorphological analysis were performed. The soils of the V order alluvial terrace showed a low degree of pedogenetic evolution, which is consistent with the very recent age of such landforms. On the Lower-?Middle Holocene and well-preserved landsurfaces of the IV order alluvial terraces, more developed soils occur, with clay illuviation features. On the landsurfaces of III, II and I order terraces, differently from the expectation, soils are less developed with respect to the IV order ones; in some cases, they show signs of inactive processes of clay illuviation. On the glacis, soils with weak signs of pedogenesis clearly dominate, while more developed soils are less frequent. Overall, the distribution model of these soils in the glacis area still remains unclear. In all cases, more developed soils only occur on the less remodeled landforms and they do not reflect the age of the geomorphological landsurfaces. Such situation is probably due to the severe erosional processes acting in a large portion of the study area, inducing rejuvenation pedogenetical processes.