142 COPPER-BEARING ROCKS OF LAKE SUPERIOR. 
From Grand. Marais westward to Poplar River the trend of the strata is 
more easterly than that of the coast, so that in looking in that direction 
these hill blocks are seen succeeding each other in such a way as to have 
suggested the very apposite epithet of “Saw Teeth Mountains.” An 
attempt to represent this appearance is made in the accompanying outline 
sketch. 
Fic. 1.—Outlines of coast hills for 20 miles above Grand Marais, Minn. 
In the woods of the North Shore away from the lake, the same feature 
is constantly repeated; ridges are everywhere met with trending with the 
strike of the formation, sloping gradually to the southeast, and dropping 
off abruptly to the northwest. This structure has been attributed by N. 
H. Winchell’ to faulting, each drop being regarded as the result of a fault. 
There may be a few such faults, but it is evident enough that the case is 
just such as is found in every region of flat-dipping hard rocks, and espe- 
cially where softer layers are interleaved, as in this case. 
On the south shore of the lake the dip is commonly higher, and 
although the same structure occurs the front slope is often flatter than the 
dip slope. In the eastern part of Keweenaw Point, where the dip flattens, 
the structure comes out finely in a series of bold ridges. Towards Portage 
Lake, however, the dip becomes as high as 50° or more, and the several 
ridges merge into one broad swell. This holds until the Porcupine Mount- 
ains are reached, where, though the dip-angle is as high as 30°, the struct- 
ure is most beautifully illustrated in the outer ridge. This ridge rises 
Report of the Geological Survey of Minnesota for 1878, p. 12. 
