on the Shores of Lake Superior. Ill 



Michipicotin and Sault St Marie, we more frequently see a 

 deflection to the west than a due north and south course, 

 which is rather normal along the northern shore proper, be- 

 tween Michipicotin and other islands, and from the Pic to 

 Fort- William ; the deep depression of the lake being no 

 doubt the cause of such a deviation, as large masses of ice 

 could accumulate in this extensive hollow cavity before spread- 

 ing again more uniformly beyond its limits. To the oscilla- 

 tions of the whole mass in it& southerly movement, accord- 

 ing to the inequalities of the surfaces, we must ascribe the 

 crossing of the straight lines at acute angles, as we observe 

 also at the present day under the glaciers, as they swell and 

 subside, and hence meet with higher and lower obstacles in 

 their irregular course between the Alpine valleys. 



In deep, narrow chasms, however, we find now and then 

 greater deviations from the normal direction of the striae, 

 where considerable masses of ice could accumulate, and move 

 between steep walls under a lateral pressure of the masses 

 moving onwards from the north. Such a chasm is seen be- 

 tween Spar Island and the main land opposite Prince's Lo- 

 cation, south of Fort- William, where the furrows and scratches 

 run nearly east and west. But here also, there is no tumul- 

 tuous disturbance in the continuation of the phenomena, such 

 as would occur if icebergs were floated and stranded against 

 the southern barrier. The same continuity of even, polished 

 surfaces, with their scratches and furrows, prevails here as 

 elsewhere. The angles which these scratches form with each 

 other are very acute, generally not exceeding 10° ; but at 

 times they diverge more, forming angles of 15°, 20°, and 25°. 

 In a few instances, I have even found localities where they 

 crossed each other at angles of no less than 30° ; but these 

 are rare exceptions. It may sometimes be noticed that the 

 lines running in one direction form a system by themselves, 

 varying very little from strict parallelism with each other, 

 but crossing another system, more or less strongly marked, 

 of other lines equally parallel with each other. At other 

 times, a system of lines, strongly marked and diverging very 

 slightly, seem to pass over another system, in which the lines 

 form various angles with each other. Again, there are 



