White, black and fossil.

"There are 3 types of continental glaciers: the ""white"" glaciers, such as Gébroulaz, where the ice is visible year-round and flows along the slope. The ""black"" glaciers, such as the one in the Col du Grand Infernet, are covered with stones and continue to flow. And finally the ""fossil"" glaciers, which subsist only in the form of traces of pebbles that take a concentric form (small waves) and where the ice has disappeared completely. The latter are immobile. This is the case below the Col du Fruit in this valley!"