New 40Ar/ 39Ar, stratigraphic and palaeoclimatic data on the Isernia La Pineta Lower Palaeolithic site, Molise, Italy

Abstract

The archaeological deposits of Isernia la Pineta are a milestone in the European context, being composed of very rich and large-sized occupation layers. The archaeological remains are characterised by the use of anvils in a very opportunistic and rapid way to produce a large number of flakes and residual cores, usually of very small size. The lithic instruments are associated with remains of large mammals, which give a clear indication of the diet. They are represented by Bison schoetensacki Freudenberg, Stephanorhinus hundsheimensis Toula , Elephas (Palaeoloxodon) namadicus Falconer e Cautley, Ursus deningeri von Reichenau, Hippopotamus cf. antiquus Desmarest, Sus scrofa L., Hemitragus cf. bonali Harlè e Stehlin, Megaceroides solilhacus Robert, Cervus elaphus cf. acoronatus Beninde, Dama dama cf. clactoniana Falconer, Capreolus sp., and Panthera leo fossilis von Reichenau. The rodent fauna is represented by Clethrionomys sp., Pliomys episcopalis Mèhely, Pliomys lenki Heller, Microtus aff. arvalis Pallas, Microtus brecciensis Gieber, Microtus ( Terricola) gr. multiplex-subterraneus, and Arvicola cantiana Hinton. The insectivores are Talpa sp., Sorex cf. runtonensis Hinton, and Crocidura sp. Two main archaeological layers have been identified. The lower one (Sector I, layer 3C) rests on a phytoclastic travertine passing laterally to a phytohermal travertine, which generated a small step in the watercourse. A sandy silt layer of lacustrine environment (layer 3b) deposited inside travertine pools and very limited phytostromatolitic travertine sediments cover this layer. The second occupation layer (layer 3a) rests on these sediments as well as on the travertines. Cross-bedded fine gravelly sands cover the deposits and are interlayered with tuffs very rich in pyroxene and sanidine. The latter gave 40Ar/ 39Ar ages of 610±10 and 606±2 ka (2σ error). This layer is covered by cross-bedded gravels weathered by a thick Alfisols with a well-expressed Bt horizon. The uppermost part of the series is composed of gravels and colluvia containing another pyroclastic layer. Sanidines of this layer yield scattered Ar/Ar ages, with a main population at about 504±14 ka. A maximum age of 474±3 ka is inferred for this layer. The Isernia travertines are not associated with hot water springs and indicate that the area was frequented at the end of an Interglacial period. The new ages demonstrate that the human frequentation occurred at the beginning of the Middle Pleistocene.