A typical glacial River. 107 



the sides and roof of the tunnel from which it emerges, are swept 

 along by the swift current, or stranded here and there in mid- 

 stream. The sand plain already mentioned borders the river for 

 a portion of its course, and is flooded when the lower tunnel is 

 obstructed. 



The archway under which the stream disappears is about fifty 

 feet high, and the tunnel retains its dimensions as far as one can 

 see by looking in at its mouth. Where the stream emerges is 

 unknown ; but the emergence could no doubt be discovered by 

 examining the border of the glacier some miles southward. No 

 explorer has yet been bold enough to enter the tunnel and drift 

 through with the stream, although this could possibly be done 

 without great danger. The greatest risk in such an undertaking 

 would be from falling blocks of ice. While I stood near the 

 mouth of the tunnel there came a roar from the dark cavern 

 within, reverberating like the explosion of a heavy blast in the 

 chambers of a mine, that undoubtedly marked the fall of an ice 

 mass from the arched roof. The course of the stream below the 

 mouth of the tunnel may be traced for some distance by scarps 

 in the ice above, formed by the settling of the roof. Some of 

 these may be traced in the illustrations. When the roof of the 

 tunnel collapses so completely as to obstruct the passage, a lake 

 is formed above the tunnel, and when the obstruction is removed 

 the streams draining the glacier are flooded. 



At the mouth of the tunnel there are always confused noises 

 and rhythmic vibrations to be heard in the dark recesses within. 

 The air is filled with pulsations like deep organ notes. It takes 

 but little imagination to transform these strange sounds into the 

 voices and songs of the my thical inhabitants of the nether regions. 



Toward the right of the tunnel, as shown on plate 14, there 

 appears a portion of the former river bed, now abandoned, owing 

 to the cutting across of a bend in the stream. The floor of this 

 old channel is mostly of clear, white ice, and has a peculiar, 

 hummocky appearance, which indicates the direction of the 

 current that once flowed over it. A portion of the bed is covered 

 with sand and gravel, and along its border are gravel terraces 

 resting on ice. These occurrences illustrate the fact that rivers 

 flowing through channels of ice are governed by the same general 

 laws as the more familiar surface streams. 



After examining this glacial river, during our first excursion 

 on the Lucia glacier, we reached its western banks by crossing 



