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Hinghiini contrasting witli that of Weymoiitli on the west and 

 still more with that of" the Nantasket areas on the east. The 

 j)romontory of Rocky Neck, northeast of Planter's Hill, at the 

 mouth of Weir River Bay, is, however, essentiiilly a part of the 

 Nantasket area, and it has been described in that relation, the 

 true or natural boundary between the Hingham and Nantasket 

 areas being marked approximately by the eastern shore of 

 Hingliam Harbor. 



On account of the more abundant drift-deposits, Hingham 

 does not present the almost continuous rock exposures which 

 characterize the Nantasket area. But, fortunately, a different 

 type of structure prevails, and extended outcrops are less essen- 

 tial to the correct interpretation of the geology. Plication, to 

 a large extent, takes the place of faulting, the sedimentary and 

 volcanic rocks being involved in deep and almost isoclinal 

 folds ; and hence, although the actual disturbance and displace- 

 ment of the strata are jjrobably greater in Hingliam than in 

 Nantasket, the beds are more continuous and more easily 

 traced in infrequent outcrops. Again, while Nantasket shows 

 repeated alternations of beds of conglomerate with flows of 

 both basic and acid lavas (melaphyr and porphyrite), the 

 porphyrite, so far as known, is wholly wanting in Hingham 

 and the melaphyr is limited to one flow or bed of great thick- 

 ness ; and the principal problem of the Nantasket area — the 

 identification of the successive flows of lava — is really not 

 presented at all to the students of Hingham geology. On the 

 other hand, while the sedimentary rocks of the Nantasket area, 

 south of the beach, are almost exclusively conglomerate, the 

 Hingham series embraces many beds of sandstone and brownish 

 slates and a great volume of pure gray slate ; and the special 

 feature of the geology of Hingham, the feature in which it 

 excels not only Nantasket but the entire Boston Basin, is the 

 extended series of alternating beds of conglomerate, sandstone, 

 and slate which it jiresents in three different sections, and the 

 seemingly clear exhibition of the relations of this conglomerate 



