THE VOLCANICS OF THE MICHIGAMME DISTRICT, 
OF MICHIGAN (PRELIMINARY). 
Tus name is given toa series of volcanic rocks occurring on 
the Upper Peninsula of Michigan, between Townships 42 and 47 
N., and Ranges 30 and 34 W. They are included between the 
Paint (Mequacumecum ) and Michigamme Rivers, and are inter- 
sected by their tributaries, the Fence (Mitchigan), the Deer, and 
the Hemlock Rivers. 
Previous work in this area.—The chief interest in the area has 
been due to the occurrence of iron ores in the sedimentary rocks 
associated with the volcanics. The iron deposits first discovered 
in this region were those lying along the Paint River near Crystal 
Falls, just outside of the immediate area under discussion, and 
were briefly mentioned by Major T. B. Brooks in his report on 
the iron-bearing rocks of Michigan.t Apparently little attention 
was paid to the district for some time after this, except by the 
prospectors, who gradually advanced with their test pits to the 
north, until the deposits along the Michigamme to the northeast 
and at Amasa to the northwest were found. 
In his report of work done on the Upper Peninsula between 
1881-4, which has just appeared, Rominger?’ refers those iron 
deposits occurring along the Michigamme River in Township 43 
N., Range 31 W., Section 4, and Township 44 N., Range 31 W., 
Sections 33 and 34, to the Huronian, corresponding to the rocks 
of the Quinnesec ore range, to which reference had been made in 
previous publications. The volcanics were not recognized as 
such, but were called diorite.4 oa 
* Geol. Sur. of Mich., Vol. I., Part I, p. 182, 1873: he writes, “Too little is 
known about the Paint River district . . . . to enable me to give anything of interest 
regarding its geological structure. The Huronian rocks are extensively developed 
there, and contain deposits of hard hematite ore.” 
2 Geol. Sur. of Mich., Vol. V., p. 32, 1895. 
3Ibid., Vol. IV., p. 82, 1881. 
4 Ibid., Vol. V., p. 37. 
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