ON THE NORTHWEST COAST OF LAKE SUPERIOR. 379 



The gorge disappears at the Great Fall, which is forty-five feet in width, and 

 eighteen feet high. In very high water this fall is probably sixty feet wide, and 

 over twenty-five feet in perpendicular height. Above this place the banks are low, 

 and the river from fifty to sixty feet wide, and so continues for half a mile, when 

 No. 154 again comes up, dipping to the southeast, at an angle of 11°, and forming 

 the walls of a gorge fifteen feet deep, and from twelve to fifteen feet in width. This 

 continues for the distance of four hundred yards, when the lower beds become very 

 hard and compact, and assume a decidedly trappous character. The rocks here 

 form several beautiful cascades, and are traversed by veins of No. 156, one of which 

 is six inches wide. Two hundred and fifty yards further on, the rock becomes still 

 more compact, and presents a somewhat crystalline aspect (No. 157) ; and imme- 

 diately beyond this, a ridge of greenstone (No. 158) crosses the river. The lower 

 part of this ridge resembles syenite (No. 159) in general appearance, while the 

 central portion is more compact, and finer-grained, and more like the ordinary 

 greenstones (No. 160). Beyond this, the river runs parallel with the ridge for half 

 a mile, when it winds through low bottoms as far as we ascended it. 



One mile beyond the last ridge mentioned, on the east side of the river, is a hill 

 composed of red clay and marl, and overlaid by boulder-drift. 



GORGE AND POTHOLES OF K AWI M B A S H RIVER. 



There are many remarkably large potholes in the rocks of this river. Indeed, 

 the river appears to have cut out the gorges by the sinking of lines of potholes, 

 which were gradually enlarged until they broke into each other. The sides of the 



