32 



is the view held by Prof. Edward Hitchcock, 1 after many years of 

 observation ; and the same conclusion has also been reached by 

 Mr. T. T. Bouve. 2 Such specific evidence as can be adduced on 

 this point will be presented after the description of the petro- 

 silex. 



The euritic, or fine-grained binary granite of this region is 

 as wide-spread, but not so abundant, as the type. The fine- 

 grained granite in the vicinity of the trilobite quarry on Quincy 

 Neck, along the east side of Payson's Hill, the west and north 

 side of Weymouth Fore River, and south and west of the 

 Braintree station on the Old Colony Railroad, may be referred 

 to this variety. In the western part of Braintree there can be 

 little doubt that the rock in question passes into the Blue Hill 

 petrosilex. The granite adjacent to the slates at 'Mill Cove, 

 in North Weymouth, is identical with that adjoining the Para- 

 doxides quarry on the opposite side of the river. These euritic 

 granites differ from the type only in texture ; they are undoubt- 

 edly identical with it in origin, and the impracticability of a 

 geographic separation becomes apparent as we study their dis- 

 tribution ; for the two varieties are everywhere found intimately 

 associated. We have just seen that the Quincy range of gran- 

 ite, though mainly composed of the typical variety, is bordered, 

 about its eastern end, by a fine-grained, sub-crystalline species ; 

 and in traversing the broad areas composed chiefly of typical 

 granite, in southern Norfolk and northern Bristol and Plymouth 

 Counties, and in Essex County, between Beverly andRockport, 

 the observer is constantly encountering small patches of this 

 rock, which is usually of a pale pink or reddish color. I have 

 seen it in Cohasset, along the Old Colony Railroad in North 

 Easton, on the New York and New England Railroad in Wal- 

 pole and Norfolk, in the vicinity of Pride's Crossing in 

 Beverly, and in the neighborhood of Rockport on Cape Ann. 

 On Marblehead Neck there is a rock which is closely associated 



1 Final Report Geol. of Mass., p. G67. 



2 Proo. Bost. Sue. Nat. Hist., xvn., 2'20. 



