EASTERN MASSACflUSETTS. 



417 



fonuing parts of one ancient crystalline series, wliicli is largely developed in 

 tlie 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 varions places penetrated by intrusive granites, which are generally more 



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



vicinity, besides the granites (jf 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 Marblchead, where they cut tlie greenish chloritic rocks, 

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

 In all these places the phenomena of disrupti(m and enclosure of fragments of 

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

 sharp und well-delhied All of these rocks, the granites included, are on 



Marblchead Neck traversed by dykes of intrusive greenstone, which arc some- 

 times A^ery similar in aspect to certain of the bedde<l dioritcs of A. Of the 

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

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

 porphyritic felsite of the ancient series. .... Reddish granulites directly un- 

 derlie the black argillites of Weymouth, and the (j^uart/ites with conglomerates 

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

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

 noticed. The Boxbury conglomerate was observed to contain pebbles of tlie 

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

 already remai'ked by Ilitclicock, fragments of argillaceous slate. In this VAm- 

 nectiou 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 Marblchead Neck, resting directly on the 

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

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



haj'dness of the cement The fact that tlie primordial strata of Braintree 



have suH'ered no metamorphism is the more significant, since the beds of sim- 

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

 liiu; strata supposed to belong to the same ancient series that underlies the 

 Brahitree beds, and are, like these, unaltered sand and mud ro"ks." (Proc. 

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



Tliis paper of Dr. Hunt's secured an 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 lijid been made as positive in character as 

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



VOL. VII. — NO. '1. 27 



m 



