Les formations liées à des écroulements rocheux : Exemples alpins

Catastrophic rockfulls generate rough detrital formations, the deposition of which is influenced by the geomorphological context. Three types may be distinguished, each one illustrated by means of examples: An accumulation of boulders at the foot of the free-face from which the rockfall triggered. According to the volume of the rockfall, the deposit ranges between a mere chaos of boulders and a huge talus. Possibly, the accumulation may dam the valley and cause the formation of a lake, progressively filled by sediments. If the rock mass breaks away in the axis of a valley, the boulders may cover a long distance, specially if they all on a glacier. Then, the deposit exhibits a trail of boulders along the axis of the valley. - When the rock mass falls on a loose soil its weight may trigger a mudflow which carries boulders at a more or less long distance, throwing aside the bigest of them which build lateral levees.