Pot-holes and Glacier Mills

GLACIOLOGYwhether the different textures of the ice established by Fisher have a primary influence upon the formation of Forbes's Bands, for instance because bubbly ice has a different viscosity from that of clear ice, or whether, on the contrary, the difference in texture is a result of pressure variations or even simply a secondary phenomenon of the glacier surface.Unfortunately technical difficulties due to rapid plastic distortion did not permit crystallographic investigations to be made of the upper Mt.Collon Glacier.It is remarkable that the wave formation of the glacier surface below the ice fall, similar to that of the water surface immediately below a water fall, is by far the most intensive at that point and flattens out in the direction of the advance.Ablation reached the following values according to measurements .madeby E.O.S. in the summer of 1950; at 2390 m. about 73 m., at 2270 m. about 78 m. and at 2220 m. about 82 m.These were exceptionally high amounts.On the other hand, it is equally remarkable that important variations of the Newtonian viscosity may occur in the interior of the glacier as was proved later in the Z'mutt tunnel (E.O.S.) which, with a length of 1060 m., had a maximum ice cover of 80 m. Finally, I must thank Mr. Fisher for his remarks which will help in the further study of the formation of Forbes's Bands.The point he has raised regarding the different conditions obtaining in different glaciers deserves particular attention.