28 GUIDE TO LOCALITIES. 



hill, a ridge of fine granite a mile wide, to Hayward creek. The 

 Paradoxides quarry is on the south bank of the creek at its mouth 

 and one-third of a mile east of the avenue. A few rods southeast 

 of the quarry the igneous contact of the slate and fine granite is 

 exposed obscurely in the marsh, as described by Wads\^orth. 

 This contact runs in a west-northwest direction to the creek, and 

 north of the creek it may be traced in the same direct line, with 

 numerous exposures over Eldridge hill. On the north side of 

 Eldridge hill the slate ends abruptly against a large trap dike which 

 undoubtedly occupies a fault fissure. These phenomena are sub- 

 stantially repeated, without the dike, in the valley of Ruggles 

 creek, north of Eldridge hill ; a long narrow belt of slate meeting 

 the fine granite on the south in an igneous contact (actually ex- 

 posed only at a few points), and on the north in a remarkably 

 straight, continuous and conspicuous fault scarp a mile long. 



From Ruggles creek, Quincy may be reached by electric cars 

 on Quincy avenue or on Washington street half a mile farther 

 north. 



BLUE HILLS OF MILTON. 



Relations of the Quincy granite to the quartz porphyry and 

 other forms of aporhyolite (felsite). 



Boute. — Train to Quincy Adams station, by New Haven road, Knee- 

 land street station, returning from this station or West Quincy ; fare, $.17. 



This excursion involves a rough walk of five or six miles, but is 

 replete with interest for the student of granitic rocks. It can 

 be made advantageously only with a guide, on account of the 

 wilderness-like character of the area ; and hence need not be de- 

 scribed in detail here. 



QUINCT (IKINITE QUARRIES. 



iJouJe.— Train to West Quincy, by New Haven road, Kneeland street 

 statiou; fare, $.15. 



The principal quarries are on the hill immediately west of the 

 railroad, extending back from one to two miles, and on North 

 Common hill nearly a mile east of the railroad. Among the fea- 

 tures of special geological interest are the joint structure — both 

 block and sheet quarries being well represented — the relations of 

 the gray aud black granites, and the intricate relations of the 



