Skiers who venture off-piste in the Sancy massif, as elsewhere, must always keep in mind that snow is not an inert material. On the contrary, it is constantly evolving and changing, under the action of its own weight, packing it down, due to the slopes’ sun exposure, and due to the difference of temperatures between day and night. When the slope is steep, like on the Sancy ridges, the mantle can quickly become unstable and generate avalanches.