300 COPPER-BEARING ROCKS OF LAKE SUPERIOR. 
due north, and to the east of it changing gradually more towards the N. N. E. 
The coast line is trending here as a whole just about N. E., but subordinately 
it gives a number of long trends corresponding to the more northerly trend 
of the rocks, as shown in Fig. 17. Until this unusual amount of northing 
y 
Scale 1 mile to 2 inches. 
Fic. 17.—Sketch-map of rock exposures near Split Rock River, Minnesota coast, T. 54, R. 8 W. 
in the strike is realized the exposures in this vicinity are confusing. The 
following is the succession of strata roughly made out for some four miles 
along the coast in the neighborhood of Split Rock River. There are prob- 
ably some gaps in the succession, and the thicknesses given are only the 
roughest approximations. Nevertheless, the section in its general features 
is correct, and will well illustrate the nature of the lower beds of this group 
