On the GR® 7, the mobility will take you from the Vosges to the Pyrennees by mainly following the watershed. You’ll walk between the North Sea – English Channel – Atlantic slope and the Mediterranean slope. From the East of Massif Central, the GR® goes towards the South. From the East it sails on the crests between the boundary of Haute-Loire and Ardèche, to join the Pilat massif to the Cévennes.
The GR® 7 follows more or less the watershed. Indeed, on your right, the waters join the North Sea, the English Channel or the Atlantic. And on your left, the Mediterranean slope. This mobility, in stages, will lead you from the Ballon d’Alsace to Andorre-la-Vieille. Two months are necessary to travel it.
From the Ballon d’Alsace, at 1247 m in height, the GR® 7 will lead you to Andorre-la-Vieille at 1409 m in height. During this trek, your stages will take you at the foot of the Mont Mézenc, then the Mont Lozère (col of Finiels) and then to the Mont Aigoual, on the barrier of the Cévennes, before reaching the Pyrenees.
From the sources of the Saône, join the water tower that constitutes the Massif Central. It will be the source, or rather the sources of Loire in the Mont Gerbier-de-Jonc, then those of Ardèche, then further the Moure de la Gardille, source of Allier and even the Lot, the Tarn and the Hérault. Some of these rivers regularly know the “épisodes cévenols” so feared (strong rains that may lead to floods).
The TopoGuides® (guide books) of the GR® 7 are not anymore published so you will have to resort to IGN maps or even better, GPX tracks that the FFRandonnée Walking Committees may give to you for the regions crossed. A proposal of digital TopoGuide® is considered for the Massif Central part.