Point of interest 

View Point: Phenomena on the Glacier

When the ice is stretched by tensile stress near to the surface, the fragile part of the glacier ice, cracks in the glacier occur, called crevasses. These are hardly deeper than 30 meters, because the ice flows plastically in deeper zones. Crevasses occur due to changes in the valley profile, unevenness in the glacier bed (e.g. thresholds), or differences in the flow velocity within the ice. Depending from the location and the direction the
following types of crevasses are distinguished: marginal, transverse and longitudinal crevasses. Over a glacier demolition a combination of longitudinal and transverse crevasses form ice towers, called Sérac. For mountain tourists the crevasses are particularly dangerous when they are hided under snow bridges. Another phenomenon on the glacier are glacier tables and sand cones. These two forms arise from the insulating effect of a large boulder or a thin fine sand mat. The underlying ice is temporarily protected from melting. Some might be surprised to see creeks meandering downhill on the glacier. They show us in an impressive way how the ice melts on the surface of the glacier. In some places these creeks disappear in large shaft-like depressions, called glacial mills. These have a diameter of few tens of centimeters up to several meters and reach usually in a series of steps down to the glacier bed.