Abstract
New burial ages of cave deposits, based on the Al/ Be cosmogenic isotope ratio technique, from three caves in the Vis Valley, located in the south-east perimeter of the “Grands-Causses” in southern France are challenging the validity of classic karstic evolution models to explain the structure and evolution of the karstic network in the region. Generally speaking, the formation of horizontal galleries at different elevations above the canyon floor is commonly used as time-markers of former regional base level positions. The burial ages obtained for the Bergougnous cave (1.2 ± 0.3 Ma, +117 m above base level -a.b.l.-) and the Scorpions cave 1.2 ± 0.4 Ma, +105 m a.b.l.) are in agreement with the regional river-incision rate (83 ± 35 m.Ma ) and conform to a classical per descensum evolution of the karst network. However, the emplacement of alluvium deposits within the Rocas cave at 0.94 ± 0.07 Ma is not consistent with a regular per descensum model. The Rocas cave is