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80 GEOLOGY OF NEW YORK CITY
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veins,
with two rolled masses of granitic matter, like big kernels, towards
the upper edge of the cliff, suggesting included ponds of granite which
have been elevated and compressed, sharing all the vicissitudes of the
inclosing schist. There were, on north and south exposures in this part
of the excavation, erect granite sections eight to ten feet wide,
conformable with the schist walls and disappearing into these by a
network of invading and parallel veinlets. In the so-called pegmatized
areas quartz inclusions and fine-ruled lines of quartz and feldspar
appear; in fact, an impregnation of articulating and scattered granitic
or quartzitic threads, stringers and nuts. Figs. 12 and 13 show the
quarrying out, with granite inclusions, of the gneiss or schistose
rocks west of 9th Avenue in the Pennsylvania Terminal.
It
seems apparent that the granite flows have, generally, at least,
entered the schists before the latter's elevation, and that the complex
represents a simultaneous catastrophe; but here, as elsewhere, there is
suggested a refusion and recrys-tallization of the schists where the
mariolitic-like pegmatiza-tion diversifies the schist with blebs,
blotches, and shreds of quartz and feldspathic lenticles. It would be
interesting to be able to follow these granite dikes deeply to their
possible sources. As they were probably, at least many of them,
intruded when the rocks were more horizontal, their ultimate
termination might be in a communal granitic stock, of which they are
the distributed and spreading tentacles. The reader will distinguish
between the granite dike-like walls and veins and the pegmatization of
the gneiss, where the latter incloses and is thickly mixed with
granitic fragments, specks, and strings.
Dr.
A. A. Julien in discussing the pegmatization of the gneiss has
suggested a descriptive term, " occlusion," to represent the
saturation of and the absorption and inclusion by the gneiss of the
granitic or granito-mineralizing menstrua, which in some way, he
states, has poured forth into the pores, laminations, and substance
itself of the gneiss. His language,
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