^ EASTERN MASSACHUSETTS, 417 



forming parts of one ancient crystalline series, which is largely developed in 

 the vicinity of Boston, and may be traced at intervals from Newport to the 

 Bay of Fundy, and beyond. To this same series I refer the great range of 

 gneissic and dioritic rocks with serpentines, chloritic, talcose and epidotic 

 schists which stretches through western New England. These ancient rocks 

 are in various places penetrated by intrusive granites, which are generally more 



or less hornblendic — the syenites of Hitchcock and others In this 



vicinity, besides the granites of Cape Ann and of Quincy, which probably be- 

 long to this class, examples of intrusive granites (or syenites) are well seen in 

 Stoneham and in Marblehead, where they cut the greenish chloritic rocks, 

 and on Marblehead Neck, where they are erupted among the felsite-porphyries. 

 In all these places the phenomena of disruption and enclosure of fragments of 

 the broken rock in the granite are well seen, the lines of contact being always 



sharp and well-defined All of these rocks, the granites included, are on 



Marblehead Neck traversed by dykes of intrusive greenstone, which are some- 

 times very similar in aspect to certain of the bedded diorites of A. Of the 

 rocks of class C, the unaltered argiUites of Braintree, holding a primordial 

 fauna, were observed by Prof. Shaler and myself to rest directly upon a hard 

 jiorphyritic felsite of the ancient series Eeddish granulites directly un- 

 derlie the Ijlack argillites of "Weymouth, and tlie ({uartzites with conglomerates 

 and argillites of Chestnut Hill Reservoir, and of Brighton near by, are in sev- 

 eral places observed in contact with the old dioritic and epidotic rocks already 

 noticed. The Eoxbury conglomerate was observed to contain pebbles of the 

 felsite-porphyries, diorites and intrusive granites of the older series, besides, as 

 already remarked by Hitchcock, fragments of argillaceous slate. In this con- 

 nection may be noticed a remarkable recomposed rock long since correctly 

 described by the same careful observer, as an aggregate of broken-up and re- 

 cemented felsite-porphyry He observed it at Hingham and Cohasset, 



and Mr. Hyatt has since found it on Marblehead Neck, resting directly on the 

 parent rock, and very firmly cemented. The unequal weathering of the sur- 

 face, however, clearly shows both its conglomerate character and the inferior 



hardness of the cement The fact that the primordial strata of Braintree 



have suffered no metamorphism is the more significant, since the beds of sim- 

 ilar age in New Brunswick and Newfoundland rest unconiormably on crystal- 

 line strata supposed to belong to the same ancient series that underlies the 

 Braintree beds, and are, like these, unaltered sand and mud rocks." (Proc. 

 Bost. Soc. Nat. Hist., 1870, XI Y., pp. 45-49.) 



This paper of Dr. Hunt's secured au amount of acceptance amongst 

 the local geologists far beyond that to which it was entitled ; especially 

 when it is remembered that it is based on simple assertion, without any 

 evidence in support of the positions taken. Moreover, these views were 

 largely in opposition to his life-long teachings, down to 18G9, and con- 

 cerning which statements had been made as positive in character as 

 those of an opposite nature here upheld. From this time onward, how- 



VOL. VII. NO. 1. • 27 



