CORE UNIT: PATTERNS AND PROCESSES IN THE PHYSICAL ENVIRONMENT
mountain slopes. On the basis of statistics over the last 55 years, one can say that on average 26 people are killed by avalanches – the white death – in Switzerland every winter. Avalanche frequency is increasing because of the growth of extreme sports like
heli-skiing where skiers are dropped off from helicopters onto unofficial (off piste) ski runs.
Fig. 15 It is important that people stay on official ski runs. Off-piste skiing can lead to avalanches.
Main processes: weathering, a trigger, gravity Example: The Conor Pass, County Kerry In mountainous areas where bare rock is exposed to weathering, earthquakes and repeated frost action may trigger rock falls. Blocks of rock fall from steep slopes. Individual blocks may fall away from (or slide down) well-developed bedding planes or joints. The falling pieces bounce and roll downhill. Over time the debris from rock falls can build up into scree (talus) slopes. Active scree slopes are characterised by angular blocks and an absence of vegetation. In this case the old saying is true – rolling stones really don’t gather any moss!