286 GEOLOGY OF THE NARRAGANSETT BASIN. 



granite mass could not have been far away. It seems probably that the 

 porphyritic granite near high-tide level may be a part of the original 

 granite mass and not a bowlder derived from the same. The existence of 

 this granite with large feldspar phenocrysts at Little Compton, and south- 

 east of Almys Pond, south of Newport, as well as at the Cormorant Rock, 

 makes such a supposition not impossible. 



PRE-CARBONIFEROUS ROCKS. 



The Island Rocks and other associated rocks off the northeast coast of 

 Sachuest Neck are all composed of a greenish rock, varying between a 

 slate and a shale, striking about N. 24° E. and clipping westward. The 

 Island Rocks resemble very much the more quartzitic rock in the hill 

 exposures east of Browns Point. The green shales are also exposed along 

 the east shore of Sachuest Neck, from a point a cpiarter of a mile south ot 

 Flint Point to the arkose promontory a quarter of a mile farther south. 

 Near its northern end the shale contains a little conglomerate, striking N. 

 43° E., dip 35° W. This changes soon to strike N. 33° E., dip 60° W., 

 this strike and dip being maintained as far as the arkose promontory. At 

 the north end of the cove, southwest of the promontory, the rocks strike 

 N. 35° E., dip 35° W. ; southward in the cove the strike changes to N. 40° 

 E., then N. 45° E. toward the southern side of the cove, changing to N. 

 30° E., dip 60° W., near the south end of the cove. The more southern 

 exposures along the cove show considerable conglomerate with angular 

 fragments, and from this point southward most of the rock is conglomeratic- 

 A whitish sandy band makes its appearance in the conglomeratic greenish 

 rock. It is similar to some of the more quartzitic rock in the Little Comp- 

 ton shale series on the hill east of Browns Point. This can be followed for 

 a considerable distance, having strike N. 30° E., dip 60° W. at the north 

 end, becoming steeper southward. The shore here makes a convex curve. 

 Toward the southern end of this the strike is still N. 33° E., dip 80° W., 

 but immediately beyond the strike becomes N. 58°' E., dip 70° E., chang- 

 ing southward to N. 53° E., clip 60° E., and then, at another convex curve 

 in the shore line, to N. 35° E., clip 45° E. Southward there is a small 

 promontory halfway between the arkose promontory and Sachuest Point 

 The strike here is N. 63° E., clip 60° E. West of the cove formed by' this 

 promontory the strike is N. 22° E., dip 80° E., becoming N. 30° E., clip 



