Mise en évidence de mouvements sur la moraine et le glacier rocheux de Sainte-Anne (Queyras, Alpes du Sud - France) : le rôle du pergélisol alpin

Abstract

— Movments difficult to interpretate have been proved on the moraine of the Ste Anne glacier by means of photogrammetry. The average annual velocity was of 0,36 m a year from 1948 to 71. A new statistical method of counting orientated blocks on the surface of rock-glaciers determines two directions of flow on accumulation. One of them, being of secondary importance, corresponds to the actual mov- ment (rightwards regarding the main direction of flow). In order to explain the older and main direction of the flow, it is necessary to refer to the internal permafrost, which can be indirectly pointed out in the Ste Anne cirque. The transition from moraine to rock-glacier has been put forwards (as a hypothesis) in the last Holocene cold fluctuations. According to this schedule, the Little Ice Age is only responsible for a reactivation of the rightwards moving accumulation.