LOWER HURONIAN AND UNDERLYING GRANITE. 269 



N. W. X, N. E. X, Sec. 18, T. 46 N. R. 29 W., Mich. 



The map is from a tracing of a manuscript copy of Brooks' Map, i inch = 200 

 feet, in the possession of the Republic Iron Co. The area represented on the large 

 scale covers a little more than the N. W. % of the N. E. X of Sec. 18, T. 46 N., R. 

 29 W. The sketch to small scale shows the relation to the trough as a whole. 



(Fig.V.) 



