1894. | NEW YORK ACADEMY OF SCIENCES. 195 
ous fusion, than those more acid ones whose production requires 
the presence of a considerable amount of water in the magma. 
That some water was present in the St. John intrusion must 
follow from the minerals present. But that it was less than 
ordinary, and scarcely in excess of what was needed for the 
mineral formation, seems probable from the following evidence: 
1. Veins, granite veins and pegmatite masses, due presumably 
to the action of highly heated water under heavy pressure, are 
usually very prominent and abundant around the edges of gran- 
ites intruded into crystalline rocks. This is notably the case, as 
Prof. Kemp informs me, with the intrusive granites of western 
Rhode Island. The pegmatite veins of eastern Connecticut, so 
well known as localities for rare minerals, are certainly in part, 
and probably all, connected with intrusive granites. These 
features are not common in the St. John area. 
2. Contact influence on the surrounding rocks is limited, and 
consists chiefly in their higher crystallization, None of the 
characteristic contact minerals, such as scapolite, sillimanite 
tourmaline, chondrodite, etc.,are to be seen; garnet, titanite and 
green pyroxene occur close to the contact, and the two former, 
at least, were very probably caused by mineral-bearing solutions 
spreading out from the edge of the granite into the surrounding 
rocks. But these are found only for a few feet from the junc- 
tion of the two. In contrast with this may be placed a granite 
from Orange county, N. Y., recently described by Prof. Kemp 
and Mr. Hollick.* This isa basic granite, probably very near 
the St. John rock in composition, and comes up through lime- 
stones not much less crystalline. But the neighboring rock is 
greatly changed, becoming very coarse, with great bunches of 
silicate minerals, and abundant development of scapolite and 
fluoric and boracic acid compounds, 
3. The granite-diorite is generally nearly uniform throughout 
any one band. But, where differentiated parts of the magma 
have come in contact, they show a great disinclination to mix or 
grade one into the other. This, along with the rarity of dykes 
or apophyses branching out from the main body, seems to indi- 
cate a very viscid magma. The characters of the Indiantown 
contact would in this case lead us to suppose that there may 
have been an unusual supply of water at the edge at that point, 
causing a differentiation of the mass, its granular character and 
the presence of pegmatite. 
4. The structural resemblance to intrusives of medium com- 
position has been already noted. 
_* The granite at Mts. Adam and Eve, Warwick, Orange Co, N. Y. By J. F 
Kemp and Arthur Hollick. Trans. N. Y. Acad. Sci,, Vol. VII., p. 638, Feb , 1894. 
