ON THE NORTHWEST SHORE OF LAKE SUPERIOR. 407 
the slates have no perceptible dip. Between the two falls, the argillaceous beds are 
extremely fissile (No. 12), for the height of fifteen or twenty feet above the river- 
level, and then become gradually more and more altered, until they assume a 
columnar structure as the greenstone-bed is approached, as shown in the second 
section on this page. 
init tic = 
The section below is among the very few where any certain connexion was seen 
between the overlying trap-beds and the large dikes. The dike, which traverses 
a. Argillaceous slate. 6. Met hosed sl c. Bed of g t d. Greenstone dike. 
the slates at this place, and sends off the sheets which overlie them, has produced 
little or no disturbance, except at the junction. A section of the rocks here, in 
ascending order, is as follows : , 
1. Quartzose schists (No. 7). 
2. Clay slates (No. 8), alternating with quartzose layers. 
3. Hornblendic schists (No. 9). 
4. The same rock (No. 10), passing into greenstone. 
5. Greenstone (No. 11), forming the dike and the overlying beds. 
The thickness of the metamorphosed beds in this section is forty-five feet. Below 
the dike, the beds have no perceptible dip; above it, they dip to the northwest, at 
a. Argillaceous slate. 
6. Me ate. 
i d. Quartzose porphyry. 
c, ¢ Greenstone, dike and bed. 
e. Spar vein. 
an angle of 5°. About two hundred yards further up stream is another dike, 
which appears to have been erupted at the same time with the one last-named, as 
