342 GEOLOGY OF THE NAEEAGANSETT BASIK 



a strike toward the west of north for the underlying strata, which would 

 agree with the exposures at Rocky Point. 



Kingstown series exposures on the western islands. FrOlU tlie JDOnnet tlie IvHlgStOWn 



series has been traced northward into western Warwick and southwestern 

 Cranston. The relationship of the overlying Dutch Island section has been 

 shown^ and similar rocks have been traced along the western part of north- 

 ern Conanicut, and others form Hope Island. The exposures at Beaver 

 Head and along the eastern shore of northern Conanicut appear to be a 

 more coaly variation, intermediate between the sandstone series beneath and 

 the green and dark-blue shales above. 



Prudence Island. — Lithologically somcwhat similar features are presented 

 along the western side of Prudence Island, where sandstones and some con- 

 glomerate occur along the shore north of Prudence Park wharf, dipping 

 eastward, on the average, about 25 '^. Overlying these are black carbona- 

 ceous shales and sandstones containing fern leaves. Higher, near the 

 wharf, are shown the dark-blue shales. If the dark-blue shales be corre- 

 lated with the green and dark-blue shales of Conanicut, and if the sand- 

 stones and conglomerates be associated with the Kingstown series as 

 shown on Dutch Island, then the coaly shales are equivalent to the black 

 shales forming the main mass of Beaver Head. Comparisons at so great 

 distances have, of course, little value. The real reason for considering the 

 sandstones and conglomerates of the western shore of Prudence Island as 

 equivalent to the top of the Saunderstown series is their situation beneath 

 a considerable thickness of shales. The thickness and lithological charac- 

 teristics of these shales seem to warrant their correlation with the great 

 body of shales on Aquidneck Island and the southern part of Conanicut 

 Island, the whole forming a geological group in the bay region of the Nar- 

 ragansett Basin, which group is here called the Aquidneck series, and 

 which overhes the Kingstown series. The unity of the shale series will be 

 discussed further on. Correlating the conglomerates on the western shore 

 of Prudence Island with the conglomerate at Beaver Head, it may be sug- 

 gested that the sections at Rocky Point may not far underlie their horizon. 



The actual exposure of sandstones and conglomerates north of the 

 wharf at Prudence Park can hardly exceed 60 feet. The overlying coaly 

 shales may possibly amount to 150 feet in thickness south of Prudence 

 Park wharf, but if that is the case they certainly thin out rapidly north- 



