The front of the nappes

The two slopes of the Chambran valley are very different: the right bank, minerals are very present. There are granites and gneiss making up the crystalline base of the Ecrins massif. On the left bank, the prairies are sandstone and chalky. These are part of the glacial thrust sheet: they are ancient sediments deposited mostly to the East, in the Alpine ocean, then carried here by compression at the time of the formation of the Alps.