The surrounding of the Great Aletsch glacier created by the ice is very impressive. Both rough and edged moraine debris and fine-grained sand as well as fine rock powder ("rock flour") grinded by the glacier have been deposited between smoothly polished boulders, so-called rock outcrops. The small and large boulders have a long way behind. Blasted from the rock walls they fell down to the large firn fields and amassed with the ice, which transported them like on a conveyor down the valley. In the area of the glacier tongue they melt out marginally of the glacier, forming the edged moraine debris.