8 Johnson and Warren — Geology of Rhode Island. 



The base of the hill on its northern and western sides has a 

 heavy covering of drift, which widens out rapidly toward the 

 south and southwest, forming a gently rising slope. The ridge 

 itself grows gradually lower toward the south and disappears 

 under the drift near a road which runs across the strike at this 

 point. On its eastern side, the foot of the ridge is marked by 

 a rather heavy talus of large and small bowlders, beyond which 

 a narrow strip of swampy land and a meadow extend the next 

 ridge. Beyond the drift to the north and west, a broad stretch 

 of low land completely isolates the hill. At the present time, 

 the lower portions and a good part of the top are covered with 

 a thick growth of small timber and heavy underbrush. 



The cumberlan elite is nowhere exposed in contact with any 

 other rock, and is separated from the nearest outcrops by bar- 

 ren areas for a distance of at least 700 feet. 



On the east, a ridge somewhat lower than the hill runs par- 

 allel to it. This is the nearest rock seen in place to the cum- 

 berlandite and consists of a fine-grained, green, chlorite-epidote 

 schist. It is cut by numerous quartz veins and granite dikes. 

 A little specular hematite may be found along the joints, and 

 small pockets of brilliant epidote crystals are often associated 

 with the veins. The lamination of the schist is at a steep angle 

 and the general trend of the formation is N.W. This ridge 

 also passes under the drift to the south. Farther to the south 

 granite comes in with abundant inclusions of schist. The schist 

 formation extends for some distance to the east and is succeeded by 

 granite. On the south the granite approaches the hill to within 

 400 or 500 yards. It is a medium grained, biotite granite 

 always showing strong evidences of shearing and possesses very 

 generally a gneissoid and in places a schistose structure. To 

 the southwest near the road to Cumberland Hills, the granite 

 is highly gneissoid and has a pinkish color and is suggestive of 

 the Milford granite several miles to the north. A considerable 

 amount of a purple fluorite is not uncommon in some parts of 

 the granite. Just north of Cumberland Hill, three large dikes 

 of granite or quartz-porphyry intrude the schists parallel to 

 their schistosity. These dikes contain numerous inclusions of 

 the schist and also of the granite. They appear to be the 

 youngest rocks in the area. Beyond the granite on the south, 

 a dark green hornblende schist, evidently a less metamorphosed 

 form of the schist on the east, comes in. 



On the southwest of the cumberlandite, some 350 yards dis- 

 tant, several large ledges of a rather coarse-grained, metamor- 

 phosed gabbro are met with. As may be seen from the map 

 the gabbro occupies a considerable area to the west of the hill, 

 about J a mile wide by f long. It outcrops in a series of heav- 

 ily glaciated ledges between which are considerable stretches 

 of low land or swamp. The eastern margin of the gabbro as 



