NORTHWEST OF LAKE S U P E R 1 O R. 



347 



Throughout the whole of this section, red marl and clay-beds are seen resting on 

 the rocks, and over a great portion of it boulder-drift occurs. It is highly probable 

 that the first two trap ridges met with in ascending the river are connected, both 

 having flowed from the same great fissure, carrying with them the sedimentary 

 rocks, and compressing them laterally, so as to produce the foldings and doublings 

 of the strata, as shown in the following figure, os well as in the section. 



In the bed of the river, where portions of the folded strata have been carried 

 away by denudation, the thin lamina? of the shales stand up like knife-blades. 



The east branch of Passabika River is much the largest, and exhibits in the first 

 few miles some little variation in the distribution of the rocks, although the main 

 features of its geology are precisely the same. The breccia continues for the dis- 

 tance of a quarter of a mile above the forks, where it is found to contain seams and 

 nests of minerals (No. 412), among which are fluor-spar and epidote, and resembles, 

 in this respect, a similar rock on Wisacode River. A short distance above this, 

 there is a fall of twenty-five feet over a bed of trap, which forms the channel of the 

 river for a long distance, when it is crossed by a dike two and a half feet in width, 

 carrying a vein of calcareous spar four inches wide, and bearing east 10° north, and 

 west 10° south. 



The next rock which comes up is like No. 399, this being found on the lake, 

 shore below the mouth of this river, in the direction of the dip. It is in beds, from 

 two to four feet thick, and dips southeast 18°. It continues to form the river-chan- 

 nel for half a mile, when it disappears beneath a bed of trap, probably the same 

 which overlies it where it was first seen. This rock bears great resemblance to 

 syenite, and might be mistaken for it in hand specimens. It belongs, however, to 

 the same beds as No. 402 of the west branch of the river. At its junction with the 

 overlying trap, mentioned above, there is a fall of ten feet, and above the fall the 

 metamorphosed rock assumes more the character of No. 401. It is seen in the 

 west bank of the river, six feet thick, and underlying the trap-bed. It is very 

 amygdaloidal. Just above this fall is a spar vein, two and a half feet wide, with an 

 east and west direction. It is accompanied by a narrow trap-dike, having the same 

 strike. About one hundred and twenty yards above the dike is a ridge of green- 

 stone (No. 413), which crosses the river, and makes a fall of thirty feet. 



Immediately beyond this ridge, contorted shales, such as were seen on the west 

 branch, occur, and form the bed and walls of the river for the distance of four hun- 

 dred yards. These shales are traversed by numerous veins containing flinty quartz 

 and various other minerals (No. 414). Some of these beds also contain numerous 

 fucoidal impressions,* such as were found in the neighbourhood of Oginekau and 

 Cut Face Rivers. (No. 415.) 



The next rock met with is greenstone, forming a ridge and crossing the river in 



* See Tab. I. C. 



