- The Setting
- The geological context
The strata in the cliffs in the Perigord, and especially those in the Vézère valley, were formed during the Upper Coniancian and Lower Santonian stages.
The area was profoundly affected by two geological phenomena connected with natural rock fissures that formed both shelters and caves.
In the lower part of these formations there is a very porous level, which became even more hollowed-out through repeated freezing and thawing. The result was the creation of a long horizontal incision in the cliffs, where humans could find shelter. The incision runs all along the Vézère valley, but disappears beneath Holocene-era sedimentary deposits in the valleys of the Vézère's tributaries. At the top of the cliffs, there is a highly karstified level, which was the origin of a great many caves – some 85% of the caves in the region are here, and more than 400 caves have been inventoried. In the Vézère valley, these caves are either very high-up and difficult to access, or they have been destroyed by erosion, which explains why so few caves have been recorded. On the other hand, in the valley of the Beune, the Vézère's main tributary, the terraced form of the cliff faces makes access much easier.
In the Black Perigord, the original distinction between habitation sites on one hand and decorated caves on the other – two distinct sets of spaces – is the result of a combination of basically geological events connected with the formation of landscapes, the erosion of the cliffs and the filling-in of the valley floors.