Archaeostratigraphic and tephro-chronologic constraints for an unknown Lower-Middle Paleolithic settlement in the Isernia urban area (central-southern Apennine, Italy)

A 50-metre-deep borehole was excavated in the urban area of Isernia (central-southern Italy). Numerous flinty gravels, some of which showed traces of human-working, were analyzed in detail in the upper part of the drilled Lower-Middle Pleistocene fluvial-marshy succession at a depth of 4.40–4.10 meters. They are concentrated exclusively in this stratigraphical interval while they are fully lacking in the other parts of the drilled succession, allowing us to interpret them as anthropogenic origin. The presence of a tephra layer, associated with the flinty layers, ⁴⁰ Ar/ ³⁹ Ar dated at 385 ± 2 ka, allow us to give a minimum age for the flinty contents and constrain them to the final part of MIS11. Chronostratigraphic comparison between well-known Isernia La Pineta Lower Paleolithic settlement (MIS 15, 583 ka) and Isernia urban area sites show the latter site was occupied by Lower-Middle Paleolithic humans ca. 200 ka later. Its age compares well with the archeo-stratigraphic succession of the Lower-Middle Paleolithic Guado S. Nicola site, located in the upper Volturno River valley close to Isernia. Paleolithic. Although our findings at the drilling site do not clarify whether the flint materials were worked by humans from the Lower or Middle Paleolithic periods. Therefore, the drilling site is the first report of the Paleolithic age in the urban area of Isernia, thereby becoming an important case-study for future investigations on the archeological contents of the subsoil of the city and its preservation. At the same time, it opens new research perspectives on the Paleolithic in the upper Volturno River, which was crucial for the diffusion of cultures between the Tyrrhenian and Adriatic Sea and throughout southern Europe.