France's iconic Chauvet cave holds mysterious spray-shaped imagery, made around the time when nearby volcanoes were spewing lava.
     Discovered in 1994 and popularized in the Werner Herzog documentary 'Cave of Forgotten Dreams', Chauvet-Pont D'Arc cave, in southern France, contains hundreds of paintings that were made as early as 37,000 years ago. One of its innermost galleries - named after a giant deer species, Megaloceros, that is depicted there - also contains a series of mysterious spray-shaped drawings, partly covered by the Megaloceros painting. A nearby gallery holds similar spray imagery, as does a wall near the cave's original entrance, but researchers have not determined what the images represent.
     The depictions are unique to Chauvet, notes Sebastien Nomade, a geoscientist at the University of Paris-Saclay in Gif-Sur-Yvette, France, who led the study. The Bas-Vivarais volcanic field, a well-known site containing more than a dozen extinct volcanoes, lies just 35 km from the cave, but only eruptions that happened before humans occupied Chauvet had been dated, Nomade says.
     In the hope of calculating the dates of younger eruptions, Nomade visited Bas-Vivarais and sampled rock from three volcanic centres. His team determined that the region had been lit up by a series of eruptions between about 19,000 years and 43,000 years ago. The events would have been dramatic 'strombolian' eruptions, Nomade says, with lava spewing 200-plus metres into the sky and flowing down the volcanoes' slopes. Each cone would have erupted once or twice before going extinct.
     Hunter-gatherers living in the region at the time must have seen the eruptions, Nomade says. "You just have to climb the small hill on top of Chauvet, and looking north you see the volcanoes. During the night you could see them glowing and you could hear the sound of the volcanic eruption."
     Meanwhile, radiocarbon dating suggests that humans occupied the Megaloceros gallery between 36,000 and 37,000 years ago, and charcoal used to paint the Megaloceros that overlays the spray-like paintings is at least 34,000-36,000 years old. "There's no way anybody could prove that it is a volcano that they depicted, but for us it's the hypothesis which is the most probable," says Nomade.
     If Nomade and his team are correct, Chauvet's volcano imagery would represent the earliest record of any eruption. Other, younger examples include a mysterious 8,600-year-old mural found on a wall at the Neolithic site of Çatalhöyük in central Turkey, which may be a map depicting a nearby volcano that erupted at around that time.
     "I think they make a pretty good case that it's potentially a depiction of the kind of volcano that one sees on the landscape," says Michael Petraglia, an archaeologist at the University of Oxford, UK. Depictions of natural events in rock art are rare, he notes, but this could be because they are too abstract or because researchers simply haven't looked. "Maybe there's more of this out there than we have realized."

Edited from Nature (15 January 2016)