42 



from Byfield, where it appears to connect with the area last 

 mentioned, along the north side of Kent's Island and Old Town 

 Hill, probably, under the drift, to Plum Island River. Still 

 farther north is the Salisbury and Newburyport band, which 

 extends from the western boundary of the formation, along 

 either side of the Merrimac to its mouth. This is the shortest 

 of all the bands, and its boundaries are the least perfectly 

 known. ^ These four granite ranges — the Ipswich, Rowley, 

 Newbury, and Salisbury ranges — are essentially parallel with 

 each other, and with the Natick and Rockport zone on the 

 south. They all narrow rapidly westward; so that only one, 

 the Salisbury range, appears to reach the western limit of the 

 formation. In the Rowley and Newbury bands, notably, the 

 granite is coarsest toward the east. Toward the northern end 

 of Essex County, in Newbury and West Newbury, granite is 

 known to exist outside of the areas indicated above. It occurs 

 in narrow bands and irregular patches, parallel, in a general 

 way, with the large areas between which they lie, and too 

 small for delineation on the map. The number and boun- 

 daries of these small areas remain to be determined. 



The granite described in the preceding pages is not known 

 to occur in Massachusetts beyond the limits here assigned to the 

 Huronian system. Two areas of " syenite," it is true, are rep- 

 resented on the geological map prepared by Prof. Hitchcock 

 as occurring in the Connecticut Valley ; one in Belchertown 

 and Ludlow, and the other in Hatfield and Whately. But 

 these rocks are really, for the most part, hornblendo-micaceous 

 granites, which have a Montalban rather than a Huronian 

 aspect, and are intimately associated with the Montalban rocks 



^ The northern half of Essex County is extensively drift covered; and, notwith- 

 standing this county was regarded by Prof. Hitchcock as, on the whole, the most 

 rocky in the State, outcrops are wanting over most of the area north of the Beverly 

 and Cape Ann range of hills. My opportunities for exploration in that region, also, 

 have been rather limited. And hence the boundaries of some of these granitic areas, 

 as they appear on the map, are, within certain limits, largely conjectural. Where out- 

 crops were wholly wanting, I have been guided by the character of the boulders 

 contained in the drift. 



