362 GEOLOGY OF THE iSTARRAGANSETT BASIN. 



Tail to Mackerel Cove and Dutch Island Harbor, probably even as far as 

 Potters Cove, north of Freebody Hill, belong to the Aquidneck shales. At 

 the former localities, sandstones and even small-pebbled conglomerates are 

 fairly common, while at the latter conglomerates and coarse-grained sand- 

 stones are altogether unknown, and sandstones of any description are 

 exceedingly rare. Nothing could be in g-reater contrast than the exposures 

 on Fox Hill and those on the main body of Conanicut from Freebody Hill 

 to Beaver Tail. There is no transition between the Kingstown series and 

 the Conanicut shales in this region. The dissimilarity here is indeed far 

 greater than farther northeast, where the Aquidneck shales contain more or 

 less sandstone. Sandstones and even a little conglomerate occur, for 

 instance, in the Aquidneck shales of Prudence Island, and in the shales on 

 Aquidneck itself, especially near the base of the formation. Sandstones 

 form a few widely distant beds also at higher altitudes in the shale series 

 on Aquidneck Island, but sandstones are not common in the upper beds 

 until the Sakonnet sandstones are reached. However, neither on Prudence 

 Island nor on Aquidneck Island is it possible to recognize a transition, 

 either lateral or vertical, from the Kingstown into the Aquidneck series. 



The Aquidneck shale series is therefore most distinct from the Kings- 

 town sandstone in the areas where the two series are most typically 

 developed — at the nearest point of approach of these areas, at Fox Hill on 

 Conanicut Island; and on the western side of Prudence Island the dips 

 indicate that the Aquidneck shales overlie the Kingstown sandstones, and 

 for the present the conclusion must be that the shales overlie the sandstone- 

 shale series, and this has been the interpretation in this monograph. 



This does not, however, overlook the facts that the shale series on 

 Prudence Island may contain rather frequent sandstone and some con- 

 glomerate beds, that on Aquidneck Island they may contain many sand- 

 stone beds near the base and a few higher, and that in Cranston, East 

 Providence, Swansea, and northward they contain so much sandstone, and 

 even conglomerate, that the two formations can no longer be distinguished, 

 but are merged into a general Carboniferous series of shales, sandstones, 

 and to some extent conglomerates. 



The distinction between Kingstown sandstones and Aquidneck shales 

 therefore disappears' in the northern part of the area comprised in the 

 bay region of the Narragansett Basin, but the difference between these 



