376 GEOLOGY OF THE In[AEEAGANSBTT EASIK 



distmct from the Kingstown series, but represent tlie lowest beds of the 

 Kingstown sandstones and shales. The detrital material of which they 

 are composed is evidence of the fact that areas of granite lay sufficiently 

 near to provide the quartz and cementing material of the arkose. The 

 angular breccia conglomerate at places north of Natick suggests that both 

 granite and quartzite existed at no great distance from the present location 

 of these beds. If this surmise be correct, we have a right to assume the 

 existence of land areas somewhere in this region. This does not demand 

 that the present granite and quartzite escarpment should have been a shore 

 line at the time the Carboniferous deposits of the Narragansett Basin were 

 formed. It is not probable that the land areas of that time were bordered 

 by such straight and abrupt escarpments. 



The present granite and quartzite escarpments had probably the fol- 

 lowing history: Before the deposition of the Carboniferous deposits a 

 widely extended area of granite, quartzites, and pre-Carboniferous shales 

 formed the floor of the basin. Part of this floor was above water level, 

 and furnished materials for arkose and conglomerates. The lowering of 

 the basin and the progressive overlapping of later deposits may have 

 entirely covered up these land areas and carried the shore line much farther 

 westward. The direction and location of these early shore lines are in 

 reahty not known. Subsequent to the deposition of the Carboniferous 

 the rocks of the entire basin were subjected to strong folding, the axes of 

 the folds running north-south. The granite and quartzite escarpment on the 

 western side of the bay represents the bed of the Carboniferous deposits, 

 brought up on the western side of a great synclinal fold. The escarpment 

 is due to subsequent erosion. 



Base of the Carboniferous south of Natick.— A milc SOUth of DaviSViUc, aloUg tho 



railroad, an abundant supply of conglomerate is to be referred rather to 

 the base of the Kingstown series than to the basal beds above mentioned. 

 From Natick to East Grreenwich and Wickford Junction the steep escarp- 

 ment continues to indicate approximately the horizon along which the basal 

 deposits occur, but no exposures are foxnid. 



South of Wickford Junction it is impossible to identify the basal 

 deposits of the Carboniferous series. It is possible that they are not exposed, 



Probable relations between the various granites and pegmatites and the Carboniferous beds.— -Tho 



VvTiter is inclined to favor the view that the Carboniferous series once 



