OHAPTEE III. 



THE WESTERN SHORE OF THE BAY. 



FROM SAUNBERSTOWlSr TO NABRAGAlSrSETT PIEB. 



ALONG THE SHORE. 



About a quarter of a mile south of Saunderstown occurs, along the 

 shore, black shaly rock, originally a very fine-grained carbonaceous sand- 

 stone, and a light-colored coarser quartzitic rock, representing an original 

 coarse-grained sandstone, with but little carbonaceous material. The shaly 

 rock is full of a micaceous mineral, and also contains black specks, which 

 in part are probably biotite and in part some other mineral. The coarse- 

 grained sandstone has black mica abundantly disseminated throughout it, 

 and not collected in patches as on Hope Island, The strike is N. 20"^ E., 

 dip 40^ E. Southward some of the coarse-grained sandstone contains white 

 mica; yet farther south very small pebbles begin to appear in the sand- 

 stone, usually in thin layers, forming a small part of the total thickness of 

 the sandstones. Black, shaly, very fine-grained i^ock continues to be inter- 

 stratified with the sandstones. Stxike N. 30"^ E., dip often as low as 25*^ E. 

 The pebbles are usually less than 1 inch long, and have been drawn out 

 and flattened by shearing. At first, black shaly rock and sandstone alter- 

 nate rather frequently just north of a small stream entering the bay; sand- 

 stone very largely predominates. South of the brook there is again an 

 alternation of sandstones and black shales, and the low dip of 30*^ E. 

 becomes 40^ E., then steeper, until it is soon practically vertical; after 

 which the dip becomes westward, about 70° W. at first, and finally, at a 

 point 1,250 feet north of the South Ferry wharf, it is 40 "^ W. Here the 

 section is cut off transversely to the strike by a large pegmatite dike. 

 Soulh of this dike the lowest rocks are black shales, almost horizontal, over- 

 lain by quartziferous sandstone with white mica, containing small pebbles, 

 overlain by black shale dipping 20° E. The low eastward dip continues 



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