The role of sculpted forms along endokarstic active conduits in the development of fluviokarstic canyons. The Rio Puron Cave conduit (Spain)

Abstract

The Purón River valley shows a special configuration due to convergence of surficial and groundwater processes in a phreatic conduit. Typical karst processes of dissolution-precipitation have been replaced by fluvial activity, where mechanical water erosion morphologies are dominant. All this seems to relate to a stage of abandonment of the underground environment in favour of the surficial domain. River incision in rock canyons is accomplished in many cases by phreatic conduits evolution, its collapse and opening to the surface. During the initial stages of this process, river piracy and superficial changes in the drainage network occur by capturing in first place the groundwater system. In this context of fluvial activity, numerous sculpted forms, such as potholes, are found in the conduit which is the result of changes and evolution in the cave into a more evolved morphology, pointing to river stream power concentration along certain conduit sections.