3 98 



typical melapliyr. Furtherniore, the mclapliyr appears to be 

 limited to one heavy bed near the base of the conglomerate 

 series ; and tlie repeated alternations of sediments and lavas so 

 characteristic of the Nantasket area are wanting in Hingham. 

 The stratigraphic eontrast is so great that a satisfactory 

 correlation is impossible with the data now at command. It 

 appears probable, however, as stated in tiie introduction, that 

 the two areas are complementary, the Hingliam series beginning 

 with approximately the same beds with which the Nantasket 

 series ends. This view naturally leads us to regard the mela[)hyr 

 of Hingham as probably e(]uivaleut to the great bed ofmelaphyr 

 near the top of the Nantasket section ; and certainly the thick 

 beds are far more likely than the thinner ones to extend over 

 considerable areas. 



Akhougli the great shite series, consisting of gray slate with- 

 out intercalated sandstone and eonglomerate, appears to cover 

 a considerable area in the northwestern corner of Hingham, it 

 is well exposed oidy on the shores of Huit's Cove and Beat's 

 Cove. These exposures, however, are sufficient to show, first, 

 that the slate is certainly conformable with and essentially a 

 continuation of the conglomerate series ; and, secondly, tiiat it 

 [)rol)ably overlies these coarser rocks. But the a])parent ai)sence 

 of fossils in the slate and the entii'e lack of outcro[)s connecting 

 the Hingham beds with the fossiliferous Cambrian slates of 

 Weymouth and Braintree leave us no certain clue to the geo- 

 logical age of the Hingham strata, except what is afforded by 

 thei)- relations to the granitic rocks and the composition of the 

 conglomerate. Fortunately, however, this evidence, which 

 will be fully set forth in a later section, is sufficiently clear to 

 permit us to say i)rovisionally that, while the granite is certainly 

 newer than the Paradoxides beds of J^raintree, the conglomerate 

 series of Hingham, like that of Nantasket, and hence the over- 

 lying slate, must be newer than the granite. 



The history of the Hingham strata may, then, Ix; outlined 

 as follows : subsequently to the deposition and plication ot 



