Mountaineering Routes : Page 324

Loose and jailing rock.—Just as avalanches are the most common mountain danger for the skier, falling rock is most common for the rock-climber. Weather is a frequent cause of rock fall; rocks are brought down by changes of temperature and resultant splitting action of intermittent freezing and thawing, as well as by heavy rain. Rock falls occur on all steep slopes, particularly in gullies and chutes. Areas of frequent rock falls may be indicated by abundant fresh scars on the rock walls, fine dust on the talus piles, or lines, grooves, and rock-strewn areas on snow beneath cliffs. A more immediate cause of rock fall is carelessness in climbing by both man and beast.