98 TRANSACTIONS OF THE [Fex. 23 
The same trend is shown in the lakes north of the Oswegatchie, 
notably in Yellow and Black lakes, the former lying close to the 
river and exactly parallel to it. As would be expected, the 
glacial scorings have the same direction, and it is possible that 
the ice has been a considerable factor in cutting the valleys ; 
but of this no proof is at hand. 
Rock Formation.—The rocks of the district are chiefly gneiss, 
limestone, sandstone, and granite; with which are associated 
limited amounts of iron ores, serpentine, pyroxenic schists, 
and hornblendie rocks, 
The areas occupied by the four important formations are 
roughly outlined upon the accompanying map, which, though 
including only a small portion of the region examined, shows 
the most interesting localities. 
Gneiss.—The gneiss forms the more elevated portions of the 
region and is the oldest of the rocks, underlying the other 
members of the series. It has no characteristics which distinguish 
it from the gneiss of the southern and western portions of the 
Adirondack region, unless it be a larger proportion of biotite, as 
compared with hornblende. The usual color is gray or red, but 
dark colored basic layers are not uncommon. Veins of quartz 
and of pegmatite are abundant, cutting the gneiss in all direc- 
tions. Jointing is pronounced at many points. The hillside 
south of Gouverneur village shows a marked step-like structure, 
due to jointing. North of the village, at EK 4, the gneiss shows 
a large number of small parallel joints, running at right angles 
to strike and dip, and separating the rock into thin layers. 
Along some of these joints slipping has occurred, causing 
miniature faults, with a maximum throw of two feet. These are 
exhibited with diagramatic perfection, as they displace a black 
hornblendic layer about one foot wide, enclosed in red gneiss, 
The gneiss shows no very pronounced effects of weathering. 
The surface is often roughened by solution of the feldspar, the 
quartz remaining intact. Oxidation of iron sometimes gives a 
red or yellow tint, extending to no great depth. Where the 
rock is coated with moss, the surface layer of perhaps 5mm. 
thickness is commonly bleached to pure white by decomposing 
organic matter derived from the moss. 
The banding and foliation of the gneiss are quite variable, 
being sometimes very pronounced, and again nearly or quite 
lacking. As they decrease the gneiss approaches, and some- 
times passes into true granite. A particularly good example of 
