NORTHWEST SHORE OF LAKE SUPERIOR. 



377 



filled with thin seams of jasper. Beyond this place, hornblendic rock is seen at 

 occasional points on the river, until the country becomes flat and swampy, and the 

 river wide and sluggish. The distance from the Lake to the point where the ex- 

 ploration of this stream ceased, was estimated at twenty miles. 



The dike which passes the mouth of Inaonani River, is a continuation of that 

 forming the " Two Islands," and bears north 30° east. The rocks in contact with 

 it are remarkably full of zeolites and thalite. The rocks described in the section of 

 that stream, extend as far as the mouth of Kawimbash River, the grit-beds being 

 overlaid by a bed of No. 630. The underlying rocks are very amygdaloidal, while 

 the trap-bed is but slightly so. It appears as if the main body of the dike, which 

 is easily broken down, had been carried away by the Lake, and left only the matter 

 which had overflowed on the northwest side remaining, supported by the more 

 compact metamorphosed beds. At a number of points, the wrinkled beds (No. 

 161) were seen on the lake-shore. The position they occupy here is between the 

 compact beds and the shaly layers, and beneath a thin breccia. These wrinkles 

 bear some resemblance to ripple-marks, and were, at first, mistaken for them. They 

 are raised from a half to three-quarters of an inch, and are about an inch in width. 

 In the mass, they look much more like piles of cordage than layers of ripple-marked 

 rocks. They are, in all probability, the result of an overflow of molten rock in a 

 somewhat viscid state. If so, I am inclined to the opinion, that the material was 

 derived mostly, if not entirely, from pre-existing grit-beds, as it differs entirely in 

 character from the basaltic beds so frequently met with. The underlying beds, as 

 well as those above it, although considered to be of volcanic origin, are still sedi- 

 mentary, and do not differ in composition from the wrinkled beds. That they were 

 sedimentary deposits, and not the result of lava currents, is conclusively shown by 

 the intercalation of thin seams of clay between them. Some of the beds are very 

 thin, and even lamellated ; some of them are very ferruginous, and others assume 

 a crystalline aspect. Many small veins of calcite and ferruginous clay fill the 

 joints and cracks, and some of them contain traces of blue carbonate of copper. 

 That the grit-beds along this part of the coast were deposited in troubled waters, 

 and subject to the action of variable currents, is shown by the great irregularity of 

 the horizontal lines of bedding ; and that they were afterwards affected by convul- 

 sive movements sufficient to throw the beds into a vertical position, is shown by 

 the section a short distance below the mouth of Inaonani River, and at many 

 other places. 



16. Kawimbash River. — The explorations on this stream were extended only to 

 the distance of four miles. At the mouth, the lower beds have been heaved up so 

 as to form an arch ; and a short distance further on is a fault, causing a displace- 

 ment in all the beds of ten feet. The lower beds are in strata, from six inches to 

 two feet thick, while the overlying bed is eighteen feet in thickness, massive, and 

 jointed perpendicularly. At one point, where the bending of the lower beds has 

 left a depression, it appears to have been filled up, previous to the deposition of the 

 overlying rock, by from one to three feet of ferruginous shaly matter. Both the 

 upper and lower rocks are amygdaloidal, and belong to the grits already described. 



