Cave clastic sediments as a tool for refining the study of human occupation of prehistoric sites: insights from the cave site of La Cala (Cilento, southern Italy)

La Cala (southern Italy) is an important prehistoric cave site containing a clastic sedimentary infill recording evidence of an almost constant human occupation from the Mousterian to the Copper Age. However, a cultural gap (estimated to be approx. 10.5-6.2 ka) has been identified between the Evolved Gravettian and the Evolved Epigravettian. This study presents a sedimentological and allostratigraphic study of the cave clastic infill. The succession at La Cala can be subdivided into four allostratigraphic units (CC1-4 in stratigraphic order), each one bounded by major erosional surfaces. The most prominent erosional surface (UN1), which separates unit CC1 from CC2, has a channel-like geometry and is directly overlaid by cross-stratified sediments, suggesting deposition in an underground stream setting. This documents an important hydrological change in the cave drainage with the development of an important phase of sediment erosion. The erosional surface UN1 stratigraphically marks the cultural time-gap revealed by the archaeological excavations, suggesting that this hiatus may be due to the erosion of sediments rather than to a lack in human occupation. This study confirms the importance of cave clastic sediments in archaeological cave sites as a helpful tool for refining the timeframe of human presence.