120 W. O. Crosby—Pinite in Eastern Massachusetts. 
sachusetts, is in Miiton, on Central Avenue, about one-fourth 
rates of the Boston basin. The contact just noticed almost cer- 
tainly marks a fault, and both it and the cleavage are at right 
angles to the strike of the beds. The stratification, however, 18 
much obscured by the cleavage, though it can still be made out 
by careful observation. 
he color of the unaltered petrosilex in this case is dark pur 
ple, and the pea-green pinite occurs in it in the form of irregu- 
lar and ill-defined masses which seem to have their major axes 
normal to the surface of the ledge. Closer observation shows 
that they follow the jointing of the petrosilex ; each joint being 
bordered on either side by pinite which exhibits a gradual pas- 
sage into normal petrosilex at a distance of a few inches. ‘The 
rather limited exposure is best in the vertical direction; and 
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