TS REGINALD ALDWORTH DALY 
ded in the granite, but the overlying loose deposits prevent the 
discovery of any definite arrangement among them. The 
granite itself has a good parallel structure, and it is important to 
note that its structure-planes are conformable in strike and dip 
with those of the adjacent schists. This same conformity was 
several times observed along this western side of the area. 
Sometimes, even at the contact, the porphyritic granite is quite 
granitic without a trace of the foliated structure. A good 
example of this appears at the contact on Hall’s hill, near 
Chesterfield factory. At this locality, too, there is no doubt as 
to the relation of the two formations. The intrusive tongues of 
porphyritic granite cut across the schists and associated gneissic 
bands in a very marked way; the sharp contrast of grain and 
composition enabling one easily to differentiate the igneous 
masses. Occasionally dikes of the porphyritic granite may be 
found traversing the schists at a distance from the contact. At 
the three corners, about a mile south of Chesterfield, numerous 
great veins of coarse pegmatite outcrop and with them occurs a 
set of true porphyritic granite dikes which are probably apophy- 
ses of the main mass, half a mile away. 
Facts of like character refer to the contact with the Beth- 
lehem gneiss on the eastern side of the oval. Field evidence 
shows that the latter is of the same metamorphic epoch to which 
the Cods mica-schist is referred; thus, the argument regarding 
the better exposed part of the boundary applies to it in its 
entirety. 
Fitzwilliam area.—We have seen already that the survey 
suspected an eruptive origin for certain parts of the porphyritic 
granite, and had cited facts,from the Fitzwilliam area as in part 
the basis for the conception. The contact line of this little patch 
of the rock is very clear in its teaching. Even more graphic 
than that of the bowlders described in the survey report*is the 
evidence where the rock is in place. About a mile southwest 
of the village the porphyritic granite is found in a pasture field 
by the roadside. Included in it are many horses of biotite- 
Vol. II, p. 471. 
