Johnson and Warren — Geology of Rhode Island. 9 



a whole takes a concave outline toward the cumberlandite and 

 in one place, almost directly west, a ridge rises to very nearly 

 the same height as the hill. It is everywhere separated from 

 the cumberlandite by drift or by swampy land entirely devoid 

 of outcrops. On the south the gabbro is bounded by the gran- 

 ite mentioned above, but the actual contact, like so many others 

 in this region, is effectually masked by a small, drift-filled 

 valley. The western boundary is somewhat indefinite, but 



C d 



a, Khodose (Cumberlandite). b, Gabbro. c, Granite, d, Metamorphic 

 sedimentaries cut by granite and quartz veins. 



The map indicates the position of the surrounding rocks as shown by out- 

 crops. 



judging from the position of the granite outcrops on the south- 

 west and northwest, its position cannot be very far from that 

 assigned to it on the map. 



On the north and northwest, the gabbro is bounded by 

 metamorphic sedimentary rocks — a quartzose-biotite schist 

 chiefly — or by granite, the latter cutting through the former 

 in the form of dikes and larger irregular masses, and litho- 

 logically like the granite on the south. Near the contact the 



