0. D. von JEngeln — Studies on Ice Structure. 473 



portions of the crumbling ice tongue or rinding its way to the 

 bottom through crevasses and moulins. 



In the middle portions of the flowing ice tongue three 

 separate zones may be conceived as existing from the surface 

 to the bottom. At the top is the brittle, crevassed mass, below it 

 the viscously(?) flowing ice, and under that a colder ice layer, 

 continuing to the bottom, which is being plastically (?) deformed 

 by reason of the pressure of the overlying ice and the frictional 

 pull the viscous intermediate layer is exerting on its upper surface. 

 On this basis a decreasing rate of flow from the surface to the 

 bottom of a glacier could be accounted for, and a greater 

 erosive power could be ascribed to the relatively more rigid, 

 colder bottom layers. 



Future Experimentation. — It would be very interesting to 

 freeze a number of blocks of ice from saline solutions of 

 progressively increasing density and slowly melt them, noting 

 the relative development of the inter-crystal grooves. Where 

 glacier ice is accessible the relative concentration of saline 

 material in the granules and in the interstitial spaces might 

 be tested by picking out a number of granules, washing 

 them with distilled water and then analyzing them for 

 salt content in comparison with a coherent mass of glacier 

 ice. It would also be worth while to attempt the compaction 

 of snow into ice under long-continued pressure and cause this 

 to flow from a lateral orifice. This experiment the writer 

 hopes to attempt in a succeeding winter. 



Geological Department, Physiography Laboratory, 

 Cornell University. 



