Formation processes and stratigraphic integrity of the Middle-to-Upper Palaeolithic sequence at Cova Gran de Santa Linya (Southeastern Prepyrenees of Lleida, Iberian Peninsula)

Abstract

Sediments from Cova Gran de Santa Linya (Southeastern Prepyrenees of Lleida, Iberia) are investigated by geoarchaeological means. Micromorphological, textural, quartz grain morphoscopy and geochemical analyses are coupled with stratigraphic and sedimentary macroscopic data to provide new insights into the formation processes and the integrity of the occupation layers and embedded sterile deposit documented at the Middle-to-Upper Palaeolithic boundary. Direct indicators of the anthropogenic and natural dynamics involved in the deposition and alteration of the sediments investigated are provided. Results reveal the presence of in situ combustion structures as a major sedimentary indicator of human activity and occupation surfaces at the site. The overall good preservation of the combustion residues indicates that occupation layers have been preserved in their original context of deposition. Traits of surface exposure in parallel to progressive lessening of evidence related to human activity at the top of the Middle Palaeolithic sequence suggest discontinuity in the occupation of the site and a possible abandonment of the rock-shelter at the end of this period. Formation processes of the sterile deposit documented between the Mousterian and the Early Upper Palaeolithic levels involved the accumulation of debris from local sediments and soils as well as from the structure of the rock-shelter. Soil-forming dynamics related to palaeoenvironmental moisture fluctuations have also been recorded throughout the sequence investigated and indicate periods of surface stability during the formation of the sterile deposit. Environmental dynamics active during the formation of the sterile partially disturbed the top of the Mousterian layer, however, our data indicate that such dynamics did not substantially affect the overall integrity of the archaeological record. Our results highlight the crucial contribution of geoarchaeology and microstratigraphy to the characterisation and assessment of the anthropogenic and natural dynamics involved in the accumulation and taphonomy of Middle-to-Upper Palaeolithic sequences.