228 GEOLOGY OP THE NABEAGAISTSETT BASEK 



end The same sandstones with thin conglomerate layers are also fomid 

 north of the wharf, as far as the obtuse northeast angle of the shore. The 

 strike here is N. 16° E., and the dip of the strata, as actually exposed, is 

 nearly vertical, though a consideration of the more southern exposures of 

 this series warrants the belief that the general dip is eastward. 



In general, the strata of Dutch Island may be described as eonsisthig 

 chiefly of sandstones with subsidiary conglomerate la}^ers, underlain on tlie 

 extreme western border by a series in which black, often coaly, shales pre- 

 dominate. The general strike is N. 20° E., becoming more directly north- 

 ward at the south end. The dip is eastward. A continuation of the strike 

 northward would carry this series to the western side of Conanicut, at the 

 southern end of the line of exposures corresponding to Slocums Ledge. 

 Here, in fact, a similar series of rocks occurs, but the strike is more north- 

 ward (N. 3° E.); the dip eastward. Continuhig the strike southward, the 

 most eastern exposure on Dutch Island should pass to the west of Beaver 

 Head or Fox Hill, the nearest part of Conanicut. Yet, even if this be the 

 case, there is no doubt that the Fox Hill strata belong to the same general 

 series, and if they represent a higher horizon there is plenty of room on 

 Conanicut for the combined series. 



The degree of metamorphism shown by the Dutch Island rocks will 

 be discussed in connection with the metamorphism shown by the corre- 

 sponding rocks on Conanicut. 



COlSrAKICUT ISIjAND. 



Sandstone and several conglomerate layers are found along the more 

 westei-n margin of the hill along the shore as far as its southwestern point, 

 the beginning of the beach. Some of the pebbles of the conglomerate layers 

 are fairly large, and one or two a little over a foot in length were found. 

 The beds containing these pebbles can not be compared, however, with the 

 Purgatory conglomerates; still, the presence of large pebbles is noteworthy. 

 Near the southern end of the series of exposures the coaly shales show 

 considerable crumpling. This becomes less marked northward, where 

 the strike is found to be N. 18*^ E., aaid the dip as low as 30*^ E. Over- 



