652 LEWIS G. WESTGATE 
granulite. A few of the smaller bands contain much muscovite 
and are well foliated. The granite-gneiss sometimes assumes a 
granulitic facies about inclusions. A good example of this 
occurs at one end of the Benvenue quarry, west of theriver. A 
fifteen-foot mass of schist is caught in the granite-gneiss, which 
is dark gray and thick-bedded, but at the contact with the schist- 
inclusion changes to a fine-grained, white granulite with minute 
scattered flakes of biotite. 
The eruptive nature of the granulite is clear. It cuts across 
the bedding of the surrounding schists ; it sends apophyses into 
them; it holds inclusions of them. That it forms one geological 
body with the granite-gneiss is shown by its gradual passage into 
the latter at several points. It is not a crushed granite, as its 
position about the border of the granite and the absence of 
any microscopical evidence of crushing would show. It is an 
example of original endomorphic contact-metamorphism of the 
granite-gneiss,_more acidic and finer grained than the main 
body of the rock. The fineness of grain and the granulitic 
structure may be due to more rapid cooling of the magma in the 
neighborhood of the contact, though there is no reason why the 
conditions and consequently the structure of the granite-gneiss 
should be different at these points from what they were about 
the whole border of the granite. The more acidic character of 
the rock at the contact has not been satisfactorily explained. 
Similar phenomena have been observed elsewhere,’ notably about 
some of the granite intrusions of France. 
Besides the contact granulite described above, granulite 
occurs in three distinct forms. It occurs (1) as bands, generally 
not over a foot in thickness, cutting the granite-gneiss in or 
across the foliation and often becoming coarser and somewhat 
pegmatitic. In many cases these bands appear to grade some- 
what abruptly into the surrounding rock. They are in a sense 
later than the granite wall-rock and may mark a closing stage 
of igneous activity, before the granite had fully hardened. it 
‘ROSENBUSCH, Massige Gesteine, p. 65. References to articles by BARROIS on 
several of these granites are given on p. 14. 
