J, P. Kimball on Iron Ores of Marquette, Michigan. 295 
angular fragments of hornblende and chlorite slates, jasper and 
a green magnesian mineral.’ It seems not unlikely that this 
tock in its further distribution may possess more decidedly the 
characters of a conglomerate, and accordingly the more closely 
bear out the lithological analogy between the lower members*of 
the Huronian series near Marquette, and their well ascertained 
characters north of the great lakes, 
The hornblendic beds are succeeded by thick beds of pure 
quartzite displaying ripple marks, passing into quartziferous con- 
lomerate on the one h and siliceous slates on the other. 
_ Some points a dark colored quartzite resembling greisen except 
_ Inthe presence of hornblende instead of mica, and clearly of 
detrital origin, next underlies the ore beds. 
Possessing the same stratigraphical conditions as the schistose 
“8, while many varieties of them are represented in the 
variable degrees of local metamorphism.” Plentiful evidence 
othe of the blending of a rock of one character into that of the 
The or the continuity between crystallized and schistose beds. 
so diorites and hyperites of this region are never porphyritie, 
on the contrary are so fine-grained as rarely to admit of the 
meni separation, or even the identification of their in- 
en 
* Foster & Whitney’s Report, ii, p. 18. 
* Compare Foster & Whitney’s Report, ii, 16. 
