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forward and by ablation is at length brought to the surface of 

 the ice and is carried on to its edge and dropped there. If the 

 material is considerable and the border of the ice remains 

 stationary tor some time, notable accumulations may result in 

 the form of border ridges constituting the variety of terminal 

 moraines designated as dump moraines. When the englacial 

 and superglacial material is inconsiderable in quantity the deposit 

 may not amount to a ridge but may yet constitute a very definite 

 and distinctive belt of material. The bowlder belts of several of 

 the interior states are classed here. They cannot be said to be 

 moraines in so far as that term implies ridging, but they are 

 terminal border deposits that have much the same significance 

 as terminal moraines and belong to the same general genetic 

 class. 



(2) Englacial or superglacial till {"upper tiir). — When this 

 englacial and superglacial material is let down over the whole 

 territory of the ice, either during its successive stages of retreat 

 or by being let down directly through the melting of the glacier 

 when it becomes stagnant, it forms a superficial sheet quite 

 analogous to the subglacial sheet already considered. This was 

 some years ago designated " upper till " by Torrell, Hitchcock, 

 Upham, and others, but because the term upper till was also used 

 to designate a re-duplication of the subglacial till sheet by many 

 other geologists, it was thought best to propose the term 

 englacial or superglacial till. There still exist differences of 

 opinion as to how much of existing deposits is to be referred to 

 englacial and how much to subglacial till, and the criteria for 

 discriminating between these are still under discussion, but the 

 importance of the classification and the significance of its bearing 

 upon the interpretation of glacial action and of glacial history 

 seems beyond question. 



(3) Medial moraines. — These familiar forms of glacial 

 deposits do not call for remark, further than to note that 

 they merge into dump moraines at the frontal edge of the ice 

 and into superglacial till in cases in which they are let directly 

 down by melting without being carried on to the terminus of the 



