41 



offshoot or spur of the large granitic area of Lynn and 

 Peabody. Similarly, the granite in Reading and Wakefield 

 may be regarded, not as an isolated mass, but as connected, 

 under the drift, with the larger tract of granite on the east. 

 This connection is indicated on the map. I have sought in 

 vain for a surface connection between the Peabody granite and 

 that in Beverly. Between this Natick and Rockport granite 

 belt and the large area of granite, already noticed, on the 

 south, are several considerable masses of this rock, of which 

 the Blue Hill range is one ; and it is probable that part at least 

 of the territory marked on the map as general Huronian, in 

 Medway, Medfield, and Franklin, now extensively drift-cov- 

 ered, is underlaid by granite. The attempt to detect any system 

 in the arrangement of these masses has been attended with poor 

 success ; and I can only say that their present complicated and 

 apparently systemless disposition appears to be due to two 

 forces operating to arrange the granite along two distinct 

 lines ; one line coinciding in direction with the Natick and 

 Rockport belt, north-east and south-west, and the other 

 having an east and west trend. It will be readily observed 

 that the Dover, Dedham, and Blue Hill granite masses are in 

 line with each other, and appear to form an east- west band of 

 this rock, connected with the Natick and Rockport band, in 

 Natick, and with the broad southern area, in Braintree. But 

 this may be illusory, a more probable view, perhaps, being 

 that these masses are portions of independent north-east and 

 south-west bands parallel with that already described, the 

 south-western extensions of which are concealed by newer 

 rocks or drift. 



North of the Natick and Rockport granite range, in Essex 

 County, we find a parallel but shorter belt stretching through 

 southern Ipswich, Hamilton, and Topsfield. The granite in 

 Essex connects this band with the longer range. Another 

 band runs with nearly the same course through Rowley and 

 Newbury, south of the river Parker, branching westerly ; and 

 north of this stream a narrow band of variable width reaches 



