Mont Aiguille is a limestone mesa, previously connected to the main body of the high plateau of the Vercors Massif. The summit is made up of lower Barremian strata, deposited during the Cretaceous period. This is the same as the plateau to the west, but not as the immediate environs: the lower slopes are composed of older Hauterivian strata. As easily observed, the bedding planes are all roughly level, although there is some inclination down to the north-east.