:1 



EASTERN MASSACHUSETTS. 



413 



111 the Bulletin of tho Essex Institute, August 20, 1869, Vol. I. 

 p. lOG, the following report occurs : 



" Professor T. Sterry Hunt of Canada gave a geological description and his- 

 tory of the New England granite formation. The investigation of the last 

 twenty years had gone very far to destroy the commonly received notion that 

 granite was the foundation of all other rocks. They were beginning to learn 

 that instead of the granites being the substrata of the globe, they were rather 

 secondary or derived rocks, — that they were once great beds of gravel or sand- 

 stone which had subsequently become crystallized. After speaking of the 

 probable age of New England granites, Professor Hunt said that in walking 

 along the sliore at Rockport, lie could see tluit the granites were distinctly strati- 

 fied with alternations of sandstone at different periods. This clearly showed 

 their sedimentary origin, and probably identified them as being the same as the 

 granites north and south, and thus enabled them to class them among the De- 

 vonian rocks. Perhaps ten thousand or fifteen thousand feet beneath them 

 might be beds holding fossils of the Silurian type, —the same beds, perhaps, 

 as those cropping out at Braintree. As compared witli the I'ocks at Braintree, 

 the granites probably were of very recent origin. From careful analysis it was 

 ascertained that the llockport granite contained traces of living organisms. 

 He would mention that with reference to aerolites, chemists had found in 

 them traces wdiich by them were regarded as certain evidence of the remains of 

 organic life." 



October 19, 1870, Dr. Hunt said that the granites of Cape Ann and 

 of Quincy were probably intrusive, (Proc. Bost. Soc. Nat. Hist., 1870, 

 XIV., p. 4G,) which agrees with tho view advanced by him in a paper 

 read before the American Association for the Advancement of Science, 

 August 20, 1870. (Am. Jour. Sci., 1871, (3) I., p. 8b.) In 1873 

 the granites of Rockport were stated by him to be distinctly eruptive. 

 (Proc. Bost. Soc. Nat. Hist., 1873, XV. p. 2G2.) Those statements, 

 then, according to Dr. Hunt's published views (Chemical Essays, p. 9), 

 necessitate a depression of the sediments, out of which the granite was 

 formed, into the solid earth to the zone of igneo-a(pieous fusion, where 

 the eruptive granite was formed. Part of tho original sandstone, how- 

 ever, remained in this zone unchanged ; while beneath, at a depth of ten 

 or fifteen thousand feet lower, the Silurian rocks retained their original 

 character, their fossils remaining imaftccted ; and this took place in the 

 "same beds, perhaps, as those cropping out at Braintree," the rock at 

 that place being, as is well known, an easily fusible argillite. Then this 

 granite was raised again to the surface, thus carrying tho argillite uu~ 

 metamorphosed twice through the zone of igneo-aqucous fusion. 



In November, 18G9, Mr. E. Bicknell annoaucod that Eozol'm Cana- 



