204 COPPER-BEARING ROCKS OF LAKE SUPERIOR. 
weenaw Point Range is one of the greatest interest. A moment’s inspection 
of the map of Plate I will serve to show that towards the east the two 
ranges are widely separated, the distance -between them, even west of the 
Ontonagon, being as much as 18 miles, while still further west they rap- 
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Fic. 3.—Map of Exposures in Vicinity of West Branch of Ontonagon River, T. 46, R.41 W., Michigan. 
idly approach, and finally join. The beds of both ranges dip northward. 
Should we suppose a continuous series beneath the intervening horizontal 
sandstone, we should obtain an incredible thickness, and one which west- 
ward must diminish with an incredible rapidity, for after the two ranges 
have joined the total apparent thickness of the Lower Division of the series 
does not exceed 33,000 feet, or only 8,000 feet more than on Keweenaw 
Point. That there is a fold beneath the sandstone-filled area seems im- 
probable. There is no sign of a southern dip along the south side of the 
Keweenaw Range during all its course from Béte Grise Bay to its junction 
with the South Range. I had at one time the idea that such a fold might 
exist,! Foster and Whitney in their report indicating the existence of a 
1See Geology of Wisconsin, Vol. III, Part I, p. 19, foot-note. 
* 
