244 GEOLOGY OF THE NARRAGANSETT BASIN. 



view, with a strike fault contact over the pegmatite; strike N. 3° E., dip 

 45° E. These Carboniferous rocks are chiefly sandstone, very quartzitic, 

 with white mica, and small specks formed by a black mineral. Some more 

 carbonaceous, darker courses come in just north of the boathouse. Alterna- 

 tions of the sandstone and darker shaly rock continue as far as 120 feet 

 beyond Watsons Pier; strike N. 7° W., dip 60° E. Lighter and darker 

 colored sandstones continue to form the shore until it begins to turn south- 

 westward, but an unusually large mass of pegmatite borders it on the east. 

 West of the angle just mentioned, which is a southward-projecting point of 

 pegmatite, the Carboniferous sandstones are seen again, with the same 

 strike, but with a nearly vertical dip. Along the shore southwestward 

 the Carboniferous rocks are exposed almost as far as the mouth of a small 

 brook, although frequently intersected along the bedding by pegmatite 

 veins, often of considerable size. The more western courses are decidedly 

 black carbonaceous shales. Before reaching the mouth of the little stream 

 pegmatite occurs in great abundance. 



About three -fourths of a mile south of Watsons Pier the coast makes 

 a projection a little like the Bonnet, but smaller. This projection is formed 

 by a rock looking in general like an ordinary light-colored granite, though 

 showing pegmatitic veining and pegmatitic structure in blotches. West of 

 the south end of this projection, and directly west of Whale Rock, there 

 appears dark shaly rock, with some sandstone The sandstone is in jDlaces 

 made up of very coarse quartz grains. Some of the shaly rock is very 

 carbonaceous; strike N. 25° E., dip about vertical. Along the more 

 southerly trend of the shore the Carboniferous rock is at first not exposed, 

 although the occurrence of the pegmatite offshore only in the form of 

 narrow dikes indicates the presence of the intersected clastic rocks, but 

 farther south there is seen a conglomerate with pebbles from one-fourth to 

 one-half an inch in diameter, quartzitic as a rule. The angle northeast of 

 the Clump Rocks is formed by pegmatite. 



The western of the Clump Rocks at the light-house is formed by an 

 ordinary granite rock of medium grain with pegmatitic dikes and blotches. 

 It includes near the top a mass of Carboniferous quartzitic sandstone, with 

 very many biotite flakes. The included piece still has an eastward dip. At 

 the water's edge on the west side is a long mass of Carboniferous rock of 



