258 GEOLOGY 



valleys parallel to the direction of movement are deepened at the 

 same time, it is doubtful if the relief of the surface is commonly 

 reduced by the erosion of an ice-cap. 



Fiords. A glacier descending into the head of a bay may gouge 

 it out to a very considerable depth, and cause its head to advance 

 into the land. When the ice finally melts, the bay, if narrow, 

 deep, and long, with high slopes, is called a fiord. Many of the 

 fiords of coasts in high latitudes have arisen in this way, and some 

 of the glaciers of these coasts are now making fiords. Fiords arise 

 in other ways also. 



The positions in which debris is carried. As a result of the 

 methods by which a glacier gets its load, debris is carried in three 

 positions: (1) the basal or subglacial, (2) the englacial, and (3) the 

 super glacial. The material picked up or rubbed off from the sur- 

 face 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 on the surface, and is therefore super- 

 glacial. Either basal or superglacial drift may become englacial, 

 as we shall see. 



The basal load of a glacier is constantly being mixed with new 

 accessions derived from ground over which the ice is passing, and 

 this admixture tells the story of the work done by the bottom of 

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

 borne from the place of origin to the place of deposition without 

 such intermixture. It is doubtful if much debris is moved along 

 beneath (that is, strictly below the bottom of) the ice, though the 

 movement of the ice would tend to drag along the loose material 

 of its bed. If drift were carried forward in such position, it would 

 be strictly subglacial. 



Transfers of load. While the origin of the load usually deter- 

 mines its position at the outset, exceptions and complications arise 

 from the transfer of load from one position to another, and from 

 the gradation of one horizon to another. 



Most of the debris gathered by ice is acquired at its bottom. 

 While such material is basal at the outset, some of it may find itself 

 above the bottom a little later. Thus when ice passes over a 

 hill, the bottom of the ice rends debris from its top. To the lee of 



