A cave carving dating back 13,000 years has been discovered - only yards from where hundreds of tourists file past every day.
Cavers from Bristol University found the etching of a mammoth in Gough's Cave at Cheddar Gorge, Somerset.
They date the engraving, which is hard to see because of erosion, back to the Upper Palaeolithic period.
It follows the discovery of presumed Mesolithic carving at the gorge in 2005.
The Ice Age etching was in a small alcove off a main footpath and was only found during a systematic sweep of the caves.
Graham Mullan, from the university's spelaeological society, said tourists would have had difficulty finding the markings.
He explained: "Unlike our previous finds of abstract designs in the caves in this area, this is a clear representation of an animal."
The society's research into the engravings is being carried out with the British Museum's Department of Prehistory and Europe.
Jill Cook, deputy keeper in the department, added: "Cave art is so rare here that we must always question and test to make sure we are getting it right.
"Opinions on this may differ but we do seem to be looking at an area of ancient rock surface and the lines which appear to form the head and back of the mammoth could have been made by a stone tool."