SO-CALLED PORPHYRITIC GNEISS OF NEW HAMPSHIRE 779 
Moreover, at Fitzwilliam, where the inclusions of the neigh- 
boring biotite-gneiss are extremely well exposed, there does not 
seem to be the slightest change in the horses. Yet there can be 
no doubt that the porphyritic granite is here distinctly eruptive 
in the gneiss. In the same way, the ancient granitite described 
on the west and northwest of the village of Antrim has produced 
no material alteration in the composition of the schist inclusions, 
for in that feature they are identical with their parent terrane for 
several miles from the contact. 
It seems reasonable, then, to conclude from the brief account 
of exomorphic contact-phenomena just given that they do not 
invalidate the argument for the porphyritic granite’s being erup- 
tive. It means that the conditions were not such as to permit of 
the development of the well-marked metamorphic aureoles which 
one might expect in invaded terranes composed of relatively 
unaltered rocks. 
Endomorphic changes — More often than not where the actual 
contact between the porphyrictic granite and the older forma- 
tions appears, there is practically little change either in the 
composition or grain of the granite. This fact is characteristic 
of apophyses as well asof the mainbody. Inthe Winnipiseogee 
and Main areas particularly, the feldspat phenocrysts and their 
matrix are remarkably persistent in the size of individual min- 
erals. The reader will remember that a broad band of the 
porphyritic granite with rare phenocrysts appears on the western 
side of the Ashuelot area, and again that, on the eastern side, 
there is evidence of fine-graining in the Bethlehem gneiss-contact 
which can hardly be explained except as belonging to a chilled 
phase of the igneous rock. It is true, however, that this phe- 
nomenon is, on the whole, rather the exception than the rule in 
the different areas. We cannot but think that the invaded 
schists must have been at a high temperature themselves when 
the granite was intruded. Witness the widespread zones of 
passage between the two. The great coarseness of the matrix 
shows that the granite was long in crystallizing and in that 
process would naturally lose much heat to the surrounding rocks. 
