The only traces left of the later occupation during the Gravettian include a child 's footprints , the charred remains of ancient hearths and carbon smoke stains from torches that lit the caves . The later Gravettian occupation , which occurred 25,000 to 27,000 years ago , left little but a child 's footprints , the charred remains of ancient hearths and carbon smoke stains from torches that lit the caves .