100 TRANSACTIONS OF THE [Fes. 23 
this is shown at B5, where the strongly foliated gneiss passes 
by insensible stages into coarse red granite, showing no trace 
of banding or foliation. It is possible that the granite is 
younger than the gneiss, the gradual passage from one to the 
other being due to the finer grain of the intruded rock near the 
contact and the subsequent effects of dynamic metamorphism. 
But the transition is so gradual that this explanation seems 
improbable, and it is rendered more so by the perfect agreement 
in the mineralogical composition of the two rocks when 
examined under the microscope. It seems necessary to regard 
the gneiss and granite as different phases of the same rock. 
The cause of the difference may be explained in two ways: 
either the granite is an unchanged remnant of a plutonic mass 
from which the gneiss is derived; or it is a result of fusion of 
the gneiss by intense metamorphism. For a choice between 
these two explanations little evidence is at hand. It is, however, 
a fact that the gneiss of this locality shows unusually pronounced 
foliation, whence it would seem that metamorphism was strong 
here, and would be more likely to produce fusion than to leave 
a considerable area unaffected. 
Limestone.—As shown on the map,a large portion of the 
region examined is underlain by limestone, which extends in an 
irregular belt many miles east and west. In age it is evidently 
next younger than the gneiss. This limestone is the source of 
most of the interesting minerals of the region, of which tourma- 
line, amphibole, pyroxene, scapolite, and serpentine are, perhaps, 
most common. But while these are developed only in certain 
localities, the limestone nearly everywhere has disseminated 
through it abundant scales of graphite and light brown mica, 
sometimes associated with grains of pyrite. 
The rock varies from dark grey to white, and is always 
coarsely crystalline. Where large surfaces are exposed a 
distinct banding is often apparent, but in most outcrops this is 
not shown, and the rock presents such a massive appearance 
that it is impossible to make out the strike and dip. Thus, in 
spite of numerous outcrops, it is a matter of much difficulty to 
ascertain the thickness of the formation, and its relations to the 
underlying and overlying rocks. 
The limestone is always greatly weathered, the most evident 
result being a gray to black surface coloration. When pyrite is 
present a yellow stain extends to some depth. Some curious 
effects have been produced by solution along the abundant joint 
planes, many outcrops being completely honeycombed in this 
way. A rounding of all edges and corners is invariably shown, 
