J.P. Kimball on Iron Ores of Marquette, Michigan. 293 
Must continue to remain an open question until it is decided by 
- however, that upon the evidence of explorers and collections, 
‘ obtained at Marquette, the metamorphie character of the North- 
thisie neiss—often granitoid, quartzite, massive feldspars, tal- 
8, hornblende and chlorite slates, seams of graphite and mag- 
-Uetie iron ore. My own observations in the Iron region im- 
_ Pressing me with the indigenous character of the larger masses 
of diorite and granite represented within the defined area of the 
jtmorphic strata, and their entire distinctness from intrusive 
or erupted masses, and concurring in the recognition of 
; ee of crystalline rocks are indigenous, and to be divisible 
Maes, two formations, Laurentian and Huron the fo: 
ie hended under the name of Azoic. 
place below the Huronian; while the only argument milita- 
YouR. Sct._Szcoxp Serres, Vou. XXXIX, No. 117.—Mar, 1865. 
. 38 
