Chronology of Upper Paleolithic human activities recorded in a stalagmite at Points Cave (Aiguze, Gard, France)

In this article, we propose an approach to reconstruct the timing of human activity at Points Cave, an Upper Paleolithic rock art site located in the middle of the Ardeche River Gorge (Rhone valley, France), based on the dating and characterisation of a stalagmite containing soot. Points Cave ('Grotte aux Points' in French), also called the 'little sister of Chauvet Cave', is famous for its parietal art including a series of dots made of palm prints. A large number of stalagmites formed in the cave during the last 500 ka. However, quarrying of the cave floors during historic times led to the partial destruction of the sedimentary deposits, and many of the stalagmites were found lying on the floor. In particular, one of them (STM-18-04) showed the presence of at least four dark layers in cross-section, which appeared as possible remnants of fire-related activities in the cave. Despite being present at the same site, no other specific link between STM-18-04 and the rock art has been documented. This stalagmite, however, allows us to identify phases of human presence, located at the cave entrance. To do so, we performed a series of analyses to determine its period of growth and the nature of the dark layers that it contains. Scanning electron microscopy and Raman microspectroscopy confirmed that the dark layers include soot, and uranium-series dating indicated that the fire events occurred, respectively, around 14,200-14,100 and 12,500 years ago, in agreement with the radiocarbon ages of charcoal specimens recovered from the excavation areas nearby. We thus highlighted phases of human activity at the site during the Upper Magdalenian and/or beginning of the Epipaleolithic. By comparing our results with the regional paleoclimatic record, the soot layers trapped in the stalagmite appear to be synchronous with two cold periods, likely the Older Dryas and the Younger Dryas.