22 ACROSS THE SUB-ARCTICS OF CANADA. 



here abrupt and precipitous, consisting of cut banks of 

 stratified clay ; in other places more receding, but by a, 

 gradual slope rising, beneath dense foliage, to an equal 

 elevation. 



At this season of the year the water being high and 

 the current swift, we made good time, covering a dis- 

 tance of sixty miles for the first full day's travel. About 

 noon on the 2nd, having reached a narrow part of the 

 river, very remarkable massive walls of ice were found 

 upon either bank, some distance above the water's edge. 

 These walls were of irregular thickness, and from eight 

 to ten feet in height ; but the most striking feature about 

 them was that they presented smooth vertical faces to 

 the river, although built of blocks of every shape and 

 shade from clear crystal to opaque mud. They extended 

 thus more or less continuously for miles down the river,, 

 and had the appearance of great masonry dykes. The 

 explanation of their existence is doubtless as follows : 

 Earlier in the season the narrowness of the channel had 

 caused the river ice to jam and greatly raised the water 

 level. After a time, when the water had reached a 

 certain height and much ice had been crowded up on the 

 shores, the jam had given way and caused the water to 

 rapidly lower to .a considerable extent, leaving the ice 

 grounded above a certain line. Thus the material for 

 the wall was deposited, and the work of constructing 

 and finishing the smooth vertical face was doubtless per- 

 formed by -the subsequent grinding of the passing jam, 

 which continued to flow in the deeper channel. After 

 the passing of the first freshet, and the formation of 

 these great ice walls, the water had gradually lowered 

 to the level at which we found it. 



