XL] GRANITES AND GRANITIC VEIN-STONES. 197 



of endogenous granite, which are seen to be transverse to the 

 strata. On one side of such a mass more than sixty feet wide, 

 the schistose strata are twisted from their regular northeast 

 strike to the northwest, and so enclosed in the granite as to 

 appear interstratified with it for short distances. The banded 

 structure of the transverse granite veins is here very marked. 

 Some portions present cleavage-planes of orthoclase six inches 

 in diameter ; other parts, which are less coarse, abound in mica. 

 Similar banded granite veins abound in the adjoining towns 

 of Newry and North Bethel, and sometimes present layers of 

 quartz six inches or more in thickness, beside large crystals of 

 mica, and more rarely apatite.* These veins are often irreg- 

 ular in shape and bulging at intervals, and they sometimes run 

 partially across the beds, which seem to have been distended 

 and disturbed ; a fact which was also observed in the thin- 

 bedded schists in contact with some of the veins in Brunswick, 

 and is apparently due to the expansive force of crystallization, 

 as noticed in 27. 



20. The locality already described at Danville offers an 

 instructive example of a phenomenon often met with in the 

 region now under consideration, where granitic masses, resist- 

 ing the actions which have degraded the soft enclosing schists, 

 stand out in relief on the surface, and seem to constitute the 

 rock of the country. A careful search will however show that 

 they are simply veins or endogenous masses of very limited 

 dimensions, rising from out of the mica-schists, which are often 

 concealed by the soil. This is well seen about the lower falls 

 of the Presumpscott, near Portland, where the mica-schists, with 

 some fine-grained gneisses, dipping southeast at angles of from 

 30 to 40, enclose large numbers of granitic veins, which, 

 though sometimes but a few inches in breadth, often measure 

 twenty or even fifty feet, and are usually very coarse grained, 

 with white mica, black tourmaline, and more rarely beryl. 



* A good example of a large vein of this kind of intersecting rocks of the 

 White Mountain series may be seen in the Ramble in the Central Park in 

 the city of New York. Its place is marked by a great erratic block perched 

 directly over the vein. 



