University or Wisconsin, 
DEPARTMENT OF GEOLOGY AND MINERALOGY, 
Madison, October 15, 1881. 
Str: I send you herewith the manuscript of my memoir on the Copper- 
Bearing or Keweenawan Rocks of Lake Superior. 
I an, sir, with great respect, your very obedient servant, 
ROLAND D. IRVING. 
RapHaEL PumPELty, 
In charge Division Mining Geology, 
United States Geological Survey, Newport, R. I. 
