r 



275 



These are. facts that harmonize perfectly with the ferruginous 

 character of the beds which, it will be observed, are very 

 similar to the rocks lying in the estuary-like prolongations of 

 the Boston basin. 



The determination of the age of these so-called Devonian 

 beds rests as yet on a very insufficient basis of facts. In 

 reality this question remains about where President Hitchcock 

 left it nearly forty years ago. This eminent observer consid- 

 ered the Norfolk County series older than the Carboniferous, 

 and the red color suggested its equivalence to the Old Red 

 Sandstone. I am not acquainted with a single characteristic of 

 the red beds of Norfolk County and Rhode Island which proves , 

 or even implies, their want of synchronism with the un crystal- 

 lines of the Boston basin, unless it be that they are less fre- 

 quently and extensively cut by intrusives . The lithological dif- 

 ferences observed are unimportant, and may be easily explained 

 as matching the unlike physical conditions which obtained in 

 the two basins during Primordial time. With respect to stra- 

 tigraphy the Norfolk County basin is, apparently, exactly paral- 

 leled, on a smaller scale, by the Newton and Natick belt of 

 conglomerate and slate ; and here we find, as already pointed 

 out, the most striking resemblance in lithology and the prob- 

 able conditions of deposition. 



CARBONIFEROUS . 



Under this head I have nothing to add to what is already 

 known ; and will simply re-affirm my belief that the rocks of 

 this age in Rhode Island and Massachusetts — chiefly gray and 

 black, sometimes reddish, shales, sandstone, and conglomerate — 

 were deposited in an arm of the Gulf of Maine, expanding and 

 deepening toward the north-east, and having its head in the ■ 

 direction of Newport and Providence. 



I have had no opportunity to study the supposed tertiary de- 

 posits in Marshfield and Duxbury, and hence these, although 

 properly coming within the scope of this paper, must necessarily 

 remain unnoticed here. 



