TRANSPORTATION OF DEBRIS 



153 



the head of a bay or the lower end of a valley to a very considerable 

 depth. When the ice melts, the bay, if narrow, deep, and long, 

 with high slopes, is called a. fiord. Many of the fiords of coasts in 

 high latitudes originated in this way, and some glaciers of these 

 a i.i sts are now mak- 

 ing fiords. Sinking 

 accompanying or 

 following glaciation, 



is also a factor in 

 the making of fiords. 

 The positions 

 in which debris is 

 carried. Debris is 

 carried in three po- 

 sitions: (i) basal or 

 suhglacial, (2) engla- 

 cial, and (3) super- 

 glacial. The material 



Fig. 152. Diagram representing a hill unworn by 

 ice, and the irregular contact of soil and rock. 



Fig. 153. Diagram showing the effect 

 wear on a hill such as is shown in Fig. 152. 



glacial 



picked up or rubbed off from the surface 

 over which the ice moves is normally carried forward in the bottom 

 of the ice, and is therefore basal; that which falls on the surface is 

 usually carried there, and is therefore superglacial. Either basal or 

 super-glacial drift may become englacial. The basal load of a glacier 

 is constantly being mixed with new drift from the ground over which 

 the ice is passing. The superglacial material, on the other hand, 

 may be borne from its place of origin to its place of deposition with- 

 out such intermixture. 



Transfers of load. Superglacial debris obviously may become 

 englacial or basal by falling into crevasses, or by being carried down 

 by descending waters. 



Debris which is basal at the outset, may become englacial or super- 

 glacial later. Thus when ice passes over a hill, the bottom of the 

 ice rends debris from 

 its top. To the lee 

 of the hill the ice 

 from either side may 

 close in under that 

 which came over the 

 top. The debris de- 

 rived from the top of a 



Fig. 154. Diagram illustrating one way in which a 

 glacier gets englacial material. 



hill by the bottom of the overriding ice 

 will then be well up in the ice (Fig. 154). 



