Hawkins — Notes on the Geology of Rhode Island. 459 



Fig. 2. 



10 20 50 



Chemical relations of the Gabbros. 



40 miles. 



Fig. 2. — The vertical component in the diagram represents femic content 

 in per cent. The horizontal component represents distance in miles from 

 Ironmine Hill, Cumberland, E. I. 



Tabulation of Norms of Gabbros of this Group in Rhode Island and 

 Vicinity. (See Fig. 2.) 



Point Locality Classification Sal Fern F P-j-0 M 



A. Cumberland, E. I., peridotite . . 9-79 9005 9-79 49-25 39-65 



B. Ironstone, Mass., gabbro 49-68 50-32 49-68 24-81 16-18 



C. Pascoag, E, I., gabbro 57-18 42-82 57-18 39-64 7-37 



D. Moosup Valley, E, I., gabbro . . 60-13 39-87 6013 27-00 11-36 



E. Preston, Conn., Cse. Hb. gabbro 57-10 40-61 57-10 34-43 618 



Sal = salic content. 



Fern = femic content, upon which the curve of fig. 2 is based. 



F — feldspar content. 



P -4- O = pyroxene -j- olivine. 



M = iron ores, including magnetite and ilmenite. 



A = accessory minerals. 



1-15% 

 9-32% 



5-81% 

 1-51% 



Analyst 



C. H. Warren 

 A. C. Hawkins 

 A. C. Hawkins 

 A. C. Hawkins 

 W. A. Drushel 



