Se ne ee Ee ee eee See 
in St. Lawrence Co., N. Y. 23 
with the overlying ore was regarded by him as eruptive. This 
schist, like the ore, varies greatly in thickness, the maximum 
observed being at least 90 feet. 
4th, Below the schist is a bed of Naar eryevalne pad 
stone, white to light gray in color; often friable near the s 
face and weathering toadark color. It holds numerous aryaute 
of bronze colored mica and, still more abundantly, graphite in 
thin scales. The thickness of this formation is not less than 
250 feet. 
5th, Is a sandstone similar in character to No. 1, described above. 
The thickness ‘as uncertain, but one outcrop is exposed not 
less than 15 fe Dr. Emmons does not mention this rock, and I 
do not thinke a8 observed it, or he certainly would have men- 
tioned it in connection with his i igneous theory for the origin of 
limestones, inasmuch as it separates two deposits of his “ primi- 
~ limestone.’ 
, Is a granular crystalline limestone closely resembling 
i 4 before describe d, but differing in containing in places 
irregular beds or veins of granite, composed of a white feldspar 
and quartz. A mineral resembling tremolite was observed in this 
formation. This association of limestone and granite is fully 
described by Dr. Emmons (pages 24 and 338 and 340), and 
seems to have afforded him the best arguments for his peculiar 
views regarding the origin of the limestone. The thickness of 
this bed could not be even approximately determined ; it is 
certainly thicker than the limestone already described. 
my survey was purely economic, having reference to 
explorations for iron ore, not much attention was paid to the 
thickness of the rocks below the ore. I consider that the series 
described has a minimum thickness of 700 feet, and probably 
much greater. raga bag this whole series and = bawnding 
not seen. This gneiss is a part of the great azoic area of north- 
ern New York, and is colored Laurentian on the geological 
map of Canada. It is lithologioally a totally different rock from 
the granite described above in No. 6 as associated with the marble, 
although Dr. Emmons seems to give them the same origin and 
e. No limestone was seen in it,—the feldspar was reddi 
and it always contained mica and often hornblende. 
This series of sandstones, limestones, and ferruginous and 
magnesian schists was not found complete, so as to display 
unmistakably the sequence of the beds except on one section, 
1. ¢@., through the west corner of the Caledonia mine lot :—and 
there the 3nd and 3rd members were of less than usual thick- 
ness. The Laurentian gneiss was not seen on this section. At 
the Kearny mine the members of the series from 1 to 4 inclusive 
