194 TRANSACTIONS OF THE [aPR. 16, 
some of which, as seen in Prof. Kemp’s collections, this speci- 
men very much resembles. 
The contact is mostly with Laurentian limestone, which is 
considerably altered, though scarcely as much as one would ex- 
pect in view of the change in the accompanying acid rocks. It 
is harder, whiter and coarser in grain, and shows in thin section 
an abundance of pyroxene crystals, now mostly serpentinized 
on the surface. Near King’s Mill several small marble quarries 
have been opened in the limestones next the granite, but they 
were soon abandoned. In one of these, close to the intrusive 
mass, garnet is largely developed, in crystals or irregular masses, 
forming nearly half the rock, and separating the pure limestone 
from the granite. It again is separated from the granite by a 
thin layer of pyroxenic gneiss and a still thinner one of pegma- 
titic material, the last composed of quite large crystals of dull 
green, rusty, weathering augite scattered through a granophyric 
mixture of quartz, orthoclase and microcline. At another part 
of the contact, near Pleasant Point, a rock composed of nearly 
pure garnet separates the limestone and granite. 
Passing northwest, away from the edge of the granite, the 
limestone is less and less altered, till at Green Head it is dark 
colored, fine grained and well stratified. 
Although elsewhere the edges of the intrusion are faulted or 
concealed, yet it appears that the limestones i in the neighborhood 
are whiter, harder and coarser than those at some distance away. 
The band next the contact on the south side of the main mass of 
granite has given the name of Marble Point to a part of Indian- 
town, and is traceable by its whiteness and coarse grain, as well 
as by its purity, for some distance in either direction. 
On the whole, the’contact effects here are quite small in view 
of the size and character of the intrusion, and it is not surpris- 
ing that the granite was considered sedimentary, with the views 
as to metamorphism then prevailing,* and the array of negative 
evidence as to its influence on the surrounding rock. The in- 
clusions were thought to be pebbles or boulders; the gneissic 
structure to show a sedimentary origin, and the different bands 
were placed in the Laurentian series, as an unconformable lower 
member. 
CHARACTER OF THE INTRUDED MAGMA. From the foregoing de- 
scription and figure, it can be seen that the granite-diorite has 
not exactly a normal granite structure, though its composition 
is within the limits of normal oranites, except for the excess of 
iron present, It seems rather to simulate the intrusive rocks of 
medium composition, which are thought to be due to true igne- 
* 1871. 
