The archaeologist Jean Clottes writes that, besides the more famous paintings in the ice-age caves of France and Spain, it has also been observed that “various objects have been either deposited or stuck into cracks of the walls, or even stuck into the ground. Those apparently non-utilitarian gestures have been noticed from Asturias in Spain to Burgundy in France, from at least the Gravettian to the end of the Magdalenian, that is, for a period which lasted for thirteen thousand to fourteen thousand years.” He goes on to ponder the meaning of these items:

Everywhere in the world caves have been considered as being the place of spirits, of gods, of fairies or of the dead. This was the case for the ancient Greek (see the River Styx) as well as for the Kalash of Pakistan. Sometimes the rocks themselves are the places where the spirits dwell. The ubiquity of this sort of belief makes it possible to extrapolate it to the Upper Paleolithic. Deliberately venturing into the depths of the rocks and of the earth—where people did not live—was not a casual sort of activity. The few who did so knew that they would have to face supernatural dangers in those awesome power-laden places. The spirits of the other-world were there within reach and this might well explain why objects were deposited as they were.

      The obvious reason for doing so was a desire to reach beyond the ordinary world, that of the living, to pierce the veil barely separating it from the supernatural forces literally at hand and to touch them either directly or by means of an offering—however symbolic it might be. Innumerable examples are available. Only a few will be mentioned, from very different social and geographical contexts. The most famous one is what occurs everyday at the Wailing Wall, in Jerusalem, where some of the faithful squeeze scraps of paper bearing their prayers into the interstices of the monumental stones. The gesture is of course meant to approach the Divinity in a place perceived as being sacred.

      In the eighties, in my capacity as director of Prehistoric Antiquities for the Midi-Pyrénées region in southern France, I had to deal with an urgent archeological excavation to be carried out not far from the sacred Massabielle cave in Lourdes, where millions of Roman Catholic pilgrims congregate each year. In the woods next to it, there was another small cave, a few hundred yards away, that is, well away from the sanctuary, in a remote place where pilgrims have no reason—and most certainly are not incited or invited—to go. Now, on one of the sides of the cave, a natural cavity in the rock, about half a cubic meter, was nearly filled with offerings and deposits of all sorts: spectacles, wallets, coins, messages, etc. In this case, it was the subterranean milieu, sanctified by its vicinity with the historical holy cave, which even in our day has been spontaneously considered by many people as a passage to the other world.

      In 1991, before visiting a rock art site in central California, our Yokuts guide carried out a propitiatory ceremony after which he asked us to deposit bits of native tobacco into the cracks of the wall right below rock paintings. Ten years later, in Montana, I saw coins, small pearls, cigarettes and other small objects deposited in the fissures of a cliff called Arrow Rock inside which the spirits, called the Little People, are believed to dwell.

      Depositing various objects into the hollows of the walls deep inside painted caves is akin to the examples cited above.  

– Jean Clottes, “Sticking bones into cracks in the Upper Paleolithic,” in Colin Renfrew and Iain Morley eds., Becoming Human: Innovation in Prehistoric Material and Spiritual Culture, 195, 208-209