J, P. Kimball on Iron Ores of Marquette, Michigan. 297 
_ thegreenstones of Keweenaw Point are intercalated conformably, 
and within the sectional development of which they are included, 
kstunconformably upon the crystalline schists of the Marquette 
- district, and hence the stratigraphical identity between the rocks 
_ tf these two districts, inferred by Mr. Rivot, is clearly out of the 
Bohemian Mts. and the superincumbent series is one merely 
__ Of special lithological characters, and not one of general struc- 
Jas assumed by Mr. Rivot. The syenite of Mt. Houghton 
M ‘ 
acter of th 
: Mr. Rivot was one of the first to assert the metamorphic char- 
) 
- Stounds of structural analogy alone, opposed the generally re- 
nie °pinton that the bedded syenites, diorites, dolerites, chlo- 
Zeolitie and epidotic amygdaloids, and so-c 
- the copper-bearing series, are erupted masses, having originated 
_ eMSuecessive overflows during the accumulation of the Paleo- 
_ Miesediments in a horizontal position. Notwithstanding the strat- 
_ puphical arrangement of this series upon the South shore-en- 
“Ghee 2? Out the theory of their metamorphic origin, certain 
ot ot 
Shore v0US of the Geological Survey of Canada upon the North 
to strengthen the view advanced by Messrs. Foster 
If the explanation of trappean overflows on 
* Geol, Survey of Canada, p. 70. 
