Paleokarst phenomena are those that at present or for some duration in the past have been decoupled from all active hydrogeochemical systems. They are widely distributed geographically and are recognized from the Lower Proterozoic onwards in the geological record. Amongst the many fascinating features that they offer for study is their exploitation as “targets” for modern karstic groundwater circulation, cavern genesis and surface landform development. This topic appears not to have been surveyed in a general manner. As a first approach, exploitation by descending meteoric waters (theper descensum waters that quantitatively dominate karst genesis) may be differentiated from ascending waters and gases (per ascersum fluids that often are heated).