1893. ] NEW YORK ACADEMY OF SCIENCES. 107 
third of the rock mass, vary in diameter from one-quarter of au 
inch to two feet, are decidedly angular, and are scattered 
through the limestone in the most irregular manner possible. 
At first glance they might be taken for abundant inclusions in 
a light colored igneous rock, and it is strange that Emmons did 
not mention the occurrence in support of his theory of the 
igneous origin of limestone. Examination of other outcrops 
of a similar nature shows that the schist fragments are the 
remains of once continuous sheets, either interbedded with or 
intruded into the limestone, which have been completely shat- 
tered in the course of metamorphism, Between extreme cases, 
like that described, and those where the schist is but slightly 
distorted, there is every possible stage. The schistose layers 
pass from gentle folds into the most elaborate contortions, in 
these the schists are often stretched apart, their edges on each 
side of the break being drawn out to thin wedge shape, some- 
times with a few flattened lenses partially connecting them. 
Complete obliteration of the original continuity is rather excep- 
tional. A peculiar feature of this distortion and fracturing, is 
that the limestone shows almost no tiace of it. It has the 
appearance of a plastic mass in which the schists could move 
with considerable freedom. The conspicuous result of meta- 
morphism in the limestone is crystallization, and this has 
obscured the mechanical effects. 
The true character of the schistose rocks is often greatly 
obscured by this contortion, with the accompanying mineralogi- 
cal changes; and it is sometimes very difficult, or even 
impossible, to decide whether they are interbedded strata or 
intrusive sheets, The smaller masses of pegmatite have been 
much shattered, and are often reduced to small lumps of quartz 
and feldspar, scattered through the limestone. But so far as 
observed, the pegmatite yields to strain only by fracturing, and 
never shows the preliminary contortion that is so general in the 
schistose layers. 
Date of Metamorphism.—A comparison of the different forma- 
tions serves to fix the time of metamorphism only in the most 
general way. It leads to the conclusion that the most intense 
metamorphism, which produced such marked changes in the 
limestone and associated rocks, occurred before upper 
Cambrian time. A second stage of metamorphism is recorded 
in the sandstone, and must therefore belong to post-Potsdam 
time. 
In conclusion, it may be added that the writer hopes to do 
further work in the neighborhood of Gouverneur, as well as in 
