260 GEOLOGY OF THE KAERAGANSETT BASIIJT. 



The nearest rocks with well-defined dips are shown in a set of large 

 sandstone exposures a moderate distance east of the three ridges named. 

 These eastern sandstone exposures show an undoubted westward dip of 

 40*^ to 45°. This is indicated both by the presence of conglomeratic layers 

 and by the distribution of a large number of plant stems. Owing to the 

 two distinct cases of westward dips east of the Pomham local syncline, one 

 in the middle ridge, the other in the sandstone quarried east of this ridge, 

 a general synclinal structure of this region seems a possibility, although 

 the probability of a series of folds here must not be excluded. 



With this possible structure in view, the conglomei*ates and sandstones 

 west of Rocky Point and east of the Pomham rocks are correlated as belong- 

 ing at least to the same general series, above the rocks found farther west- 

 ward in Warwick. In other words, these rocks are believed either to overlie 

 the Saunderstown sandstone series as a distinct superior formation or to form 

 the summit of that series. 



If this be true, the sandstones and conglomerates east of the Provi- 

 dence River must dip southeastward on approaching Rumstick Neck, in 

 order to underlie the exposures south of that neck, if the shales of the latter 

 are to be correlated with the Aquidneck series. The exposures within the 

 writer's field are inadequate to settle this question. 



RUMSTICK ISTEOK. 



The first exposures eastward of Providence River, in Barrington, occur 

 along the southeastern shore of Rumstick Neck. About a quarter of a mile 

 west of the southern end of the neck lies Long Ledge, made up of Carbon- 

 iferous sandstone with strike N.-S. and dip 30^ E. A little southeast 

 the same sandstone is exposed in Rumstick Rock with strike of E.-W. 

 and dip 45° N. ' The sandstone here contains impressions of plant stems — 

 one like calamites, the others coarsely ridged. They are of the same 

 type as those found at Hills Grove, east of Providence River, north and 

 south of Silver Spring, in the quarry east of the range of three ledges, 

 northeast of Riverside, and elsewhere. On the shore itself is greenish shale 

 of the same type as that belonging to the shale series northward. It seems 

 to have a strike of N. 20° W., dip 30° E., and evidently overlies the sand- 

 stone of the ledges. 



