802 ROLLIN D. SALISBURY 



or 200 feet high, and, in extreme cases, as much as 300 feet. In 

 the case of several glaciers, however, phenomena were seen 

 which seem to throw doubt on the conclusion which at first 

 sight seemed obvious. Where considerable streams plunge over 

 the vertical faces of the glaciers, and cut gorges in this apparent 

 embankment, it is now and then seen that the embankment is, 

 after all, not composed entirely of drift, but that it is really 

 glacier ice so full of debris that it has practically lost its motion, 

 and that its outer surface only is coated with drift, free from ice. 

 It is readily seen how this coating would be a necessity. As the 

 debris-charged ice melts on the exterior, the debris which it held 

 is loosened, and if the face of the ice be steep, slides down and 

 comes to rest at such an angle as it is capable of assuming. If 

 this process be carried on for a long period of time, the result is 

 such as to give the impression of a great morainic embankment, 

 when in reality much of the apparent embankment is ice, full of 

 debris. In some sense, however, it is not wrong to look upon 

 this apparent embankment of drift as really such, for were the 

 ice in it to melt, a great embankment would still remain, but little 

 less in height in some cases than it now appears ; for the ice is 

 often so full of debris that it comes to occupy only the interspaces 

 between the stones and sand grains, and melting would not 

 allow the drift to settle together to such an extent as to greatly 

 diminish the height of the apparent embankment. 



This conclusion is confirmed by phenomena seen at several 

 points. In some cases small glaciers which had the habit of 

 making these terminal embankments have disappeared or 

 retreated, and the embankments which they had constructed, 

 remain. This is shown in Fig. 31, which represents the morainic 

 embankment left by an extinct cliff glacier^ on the north side of 

 Herbert Island. Several similar embankments occur in the 

 same region. 



In no case was the total apparent embankment determined to 

 be of ice-filled debris, but in one place glacier ice was seen no 

 feet below the apparent top of the embankment, so that the 



^For definition of cliff glaciers, see this Journal, Vol. Ill, p. 888. 



I 



