A small plane cutter!

"The glaciers behave like very large ""planes"". In a period of advance, they tear blocks of rock out of the mountain and crush them. Depending on the hardness of the rocks, this erosion happens relatively quickly. There is therefore a “rock bar” downstream of each glacial plateau. The slopes that you’ve just passed between the plateau of Plan de Tuéda and that of the Fruit are a fine example of this."