Post‐Compressive Incision of the Pyrenean Valleys

Distinguishing the external and internal forcing parameters controlling the evolution (growth/decay) of mountain chains relies on knowledge of the chronologies of deformation, exhumation and sedimentation. The large-scale objective of this chapter is to show how Pyrenean karsts have made it possible to reconstruct the history of valley incision and to characterize the response according to the maritime front (Atlantic, Mediterranean) and geodynamic or climatic events (sometimes acting jointly as during the Messinian salinity crisis). The results obtained by cosmogenic dating of sediments trapped in karst, across the entire Pyrenean chain, are presented. The insights provided by the use of these tools as well as a critical analysis of this methodology are also discussed. The chapter presents the essential elements of dating by cosmogenic nuclides in a karst context. Karst landscapes result from dissolution–precipitation processes in bedrock, generally limestone, by meteoric or hydrothermal waters.