1893. } NEW YORK ACADEMY OF SCIENCES. 203 
PETROGRAPHY OF THE GNEISSES OF THE TOWN OF 
GOUVERNEDUR, N. Y. 
BY C. H. SMYTH, JR. 
INTRODUCTION. 
In a previous communication* the writer has given a brief 
description of the main geological features of a portion of the 
towns of Gouverneur and Fowler, St. Lawrence County, New 
York. It is the aim of the present paper to set forth briefly the 
petrographic characters of the formations there discussed. 
Rocks, which, like the limestone and sandstone, though of great 
stratigraphic importance, are comparatively simple and uniform 
in composition, receive little attention; while considerable 
space is sometimes given to rocks of limited extent, but of more 
interest from a petrographic standpoint. It is hoped that the 
facts here recorded may be of value as a basis for comparison 
in future work on the geology of the Adirondack region, The 
writer is indebted to the Geological Department of Columbia 
College for the grinding of all rock-sections used in the 
preparation of this paper, and takes pleasure in expressing his 
appreciation of this material assistance. 
GNEISS, 
While as a whole the gneiss presents a great sameness over 
wide areas, still local variations are so numerous and diverse 
that the limits of this paper would hardly suffice for their 
description, Therefore, only the general character of the 
gneiss, together with a few of its more important modifications, 
will be described. 
The color of the unweathered gneiss is generally gray, less 
often red, and varies from this to black, the Jatter color being 
confined to distinct layers and lenticular patches. The banding 
and foliation vary greatly, being sometimes marked and again 
wholly absent. Thus considerable areas in the gneiss have all 
the characters of granite, and this is commonly the case with 
hand specimens. 
**“ A Geological (Reconnoissance in the Vicinity of Gouverneur.” N. Y. 
Trans. N, Y. Acad. Sci., XII., p. 97. 
