Since the Aurignacian period (Castanet Shelter), loops were carved into rock walls and stones. The rock was pierced to allow a line to be threaded through, and their placement was deliberate. In the Magdalenian era, at Roc-aux-Sorciers for example, these loops are located on the vertical edges of walls and sometimes on horizontal ridges, and are grouped in series from the top to bottom of the frieze, from the vault down to bedrock. Loops may have played a role in the installation of enclosing structures for protecting and closing off various living areas. Beyond this functional aspect, the rings play a part in the organization of figures by making separations between various thematic registers. They frequently are associated with figurative sculptural elements, including bison at Roc-aux-Sorciers and horses at Cap Blanc.