La foux de la Vis , or resurgence of la Foux , is a karstic resurgence located in the town of Vissec in the Gard . The Vis takes its sourcein the Cévennes National Park , flows to Alzon before getting lost at the Larcy mill, which leaves a dry bed (the Vis sec around Vissec ); the buried water then joins an underground network to resurface with the madness of the Vis . During geological times, theVis has dug a canyon , the Vis gorges , which separates the Causse de Blandas from the Causse de Campestre , then from the Causse du Larzac .