BOUNDARY OF THE BASIN. 125 



Sir Charles Lyell's map of 1845 is fairly accurate as regards the 

 boundaries of the basin, but the southern half of the Massachusetts 

 extension of the Carboniferous is erroneously colored to represent the Old 

 Red sandstone, or Devonian. The connection with the Norfolk County 

 Basin is not shown. 1 



Sir W. E. Logan, in the geological map of Canada, dated 1864, 

 accompanying the Atlas of 1865, represents, on the authority of James 

 Hall, the outlines of the Carboniferous basin and its connection with the 

 Norfolk County Basin, the beds of which latter field are for the first time 

 colored as Carboniferous. 



C. H. Hitchcock published a map in 1871 in which a barrier of 

 granitic rocks between the red beds of the Narragansett Basin and the 

 Norfolk Basin is again erroneously introduced. Other changes in the west- 

 ern boundary are made by referring a belt of strata to the Silurian. 



W. 0. Crosby's map of 1877 gives a generalized boundary of the 

 northern part of the basin, and an attempt is made to show the connection 

 between the Narragansett and Norfolk County basins. The Carboniferous 

 is shown extending as a tongue northward to Norwood in the Norfolk 

 County Basin, the underlying beds being, on the authority of Edward 

 Hitchcock, represented as Devonian. 



In 1880 Crosby and Barton published an account of their tracing the 

 beds of the Norfolk County Basin into the Narragansett Basin, and stated 

 their reasons for considering all the beds to be Carboniferous, but they did 

 not publish a map. 



The latest compiled general geological maps of the United States 2 

 perpetuate the error in regard to the nature of the connection between the 

 Norfolk and Narragansett basins, a bond which was correctly shown on 

 Logan and Hall's map of 1864, and still earlier under the coloring- of 

 Devonian in the Hitchcock map of 1841. 



BOUNDARY OF THE BASIN ON THE >'OETH AND EAST. 

 From Cranston to the Blackstone River. 111 the SOUtllWeSt COl'Iiei' of the Pl'OvidenCe 



quadrangle the basal beds of the Carboniferous are seen standing in nearly 

 vertical attitude against the boundary wall of the pre-Carboniferous series. 



1 Travels in North America, Vol. II, New York, 1845, PI. II. 



2 C. E. Van Hise, after McGee and Hitchcock: Bull. U. S. Geol. Survey No. 86, PI. XI. W. J. 

 Mc-Gee: Fifth Ann. Eept. U. S. Geol. Survey, 1884, PL II. 



