SECTION OF THE ROCKS OF THE ISLAND OF 

 RHODE ISLAND. 



Plate 6. 



1st Granite. — (See plate 6, fig- 1.) This rock 

 shows itself, at the south end of this Island, and 

 is a close-grained compound of Quartz, Mica and 

 Feldspar, with occasionally some Hornblende ; one 

 variety has small green specks resembling Ser- 

 pentine. 



It is not overlaid by Gneiss, as on the Island of 

 New York, there is however one variety of the 

 Gra.ywacke, (which appears to run into Gneiss,) 

 which has a small quantity of Mica in its compo- 

 sition. 



2nd Serpentine. — (See plate 6, fig. 2.) The 

 locality of this rock is between the town of New- 

 port and Fort Adams, near the Granite ; it is a 

 black variety of nearly the same quality as the 

 Serpentine of New York Island. 



3d Talcose Slate.— (See plate G,fig. 3.) This 

 rock, may be seen at Fort Adams, in the area of 



