400 Emmons on American Geology. 
Mr. Emmons brings forward many cases in illustration of his 
theory of the hypogene origin of these crystalline erat such 
as their occurrence in veins and intruded masses among the feld- 
spathic and quartzose rocks of the region. ‘That te cases exist 
is very true; but any one who has intelligently studied them, 
will admit that the limestones are nevertheless interstratified with 
these felspathic and quartzose rocks, and that they may be traced 
for miles in the direction of the undulations, maintaining through- 
out, the same relation to the spew dice strata. e 8 
from personal obServation. ‘T'his is in so evident, that Mr. 
Emmons both in his Geological Report, pare in the present work, 
finds no other means of describing the distribution of these lime- 
stones in New York, than to speak of them as beds, running 
N. E. and S.W. At the same time, Mr. Hunt, in the paper already 
referred to, observes that the limestone appears at some period to 
have heen ‘rendered almost liquid, oy to have been subjected at 
the same time to great ~ re, so that in many cases, it has 
flowed around and among the Srblioh and often distorted frag- 
ments of the Sees silicions strata, as if it had been an 
injected hypogene rock.” (This Journal, [2], xviii, p. 194. 
The cryenlne ca es of Pennsylvania, Virginia, and North 
Carolina are described by our author as “ranges belonging to the 
laminated and schistose rocks,” yet he says, ‘all these limestones 
must be regarded as belonging to the eruptive class, p. 83. Ac- 
cording to him they resemble the limestones of the Hoosick range 
in Western Massachusetts, which are also pyrocrystalline, and are 
not to be confounded with the Vermont and Berkshire marbles, 
“which are of sedimentary origin and belong to the Taconic 
em.” He then tells us‘that these two limestones are related 
to each other as granite and gneiss, as if he admitted the sedi- 
mentary origin of gneiss, which he has already classed with 
granite as pyrocrystalline. The distinction which he draws be- 
tween the Washington and Pittsfield marbles is as baseless as the 
onic system to which he refers the latter. Both of these 
limestones belong to a single formation which may be traced with 
a sie outcrop, from the exposures holding Trenton fossils 
near Missisquoi Bay, in Canada, through the marbles of Rut- 
land, of Berkshire and of Westchester Co., N. Y., the alteration 
dually increasing, until we reach nge Co., New York, an 
x Co., N. Jersey. Yet the sedimentary’ origin of these rocks 
is not more clearly marked, than is that of those of the Lauren- 
tian , which, having been disturbed and rendered crystalline, 
are, along their whole outcrop in Canada and New York, covered 
by the unaltered and horizontal paleozoic strata of the New York 
ne Le base of which is sometimes a conglomerate of these 
chit the eruption of the +, 
n the face of these facts NV . Emmons would 
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