158 E. M. Deeley and G. Fletcher— Structure of Glacier-Ice. 



produce large fissures in the ice, and the consequent sliding of one 

 detached part over another, but rather the effect of a general bruise 

 over a considerable space of the yielding body. According to this 



Fig. 5. (x) Horizontal section. Obergrindelwald Glacier. 



view, the delicate veins seen in the glacier, often less than a quarter 

 of an inch wide, have their course parallel to the direction of the 

 sliding effort of one portion of the ice over another." That, in a 



Fig. 6. {{) Horizontal slice from Eismeer of Untergrindelwald Glacier— from 



beneath medial moraine. Here the ice was clear blue. No veining seen. 

 Fig. 7. (t) Vertical section from Mer de Glace Glacier. 



few words, the veining is due to the formation of a series of discon- 

 tinuous shear planes. Unfortunately, in his early letters Forbes was 

 led to say that the well-known " dirt-bands " . . . . " are nothing 



