THE CARBONIFEROUS BASIN. 



121 



GENERAL STRUCTURE OF THE BASIN. 



The broader secondary features of the basin — the system of folds with 

 their axes and the parallel direction of the borders — are relatively simple. 

 The structural outline of the basin is that of a ship's knee, with the 

 angle on the northwest, one arm extending southward to the mouth of 

 Narragansett Bay, the 



7/°30' y/o/S' i/onn -tn°AX' 



other eastward toward 

 Cape Cod Bay, and the 

 inner curve forming the 

 border from Tiverton 

 northeastward to Lake- 

 ville. If a line be drawn 

 from the northwestern 

 corner near Diamond 

 Hill (see fig. 7) south- 

 eastward to a bisection 

 of the curvilinear border 

 near Fall River, it will 

 pass through the three 

 deep synclinal depres- 

 sions in which the upper- 

 most conglomerates of 

 the Carboniferous have 

 been infolded and pre- 

 served from denudation. 

 On the northwest this 

 line also passes through 

 the small area of pro- 

 found dislocation and 

 uplift which brings the 

 granitite of H o p p i n 

 Hill, the Cambrian, and 

 the lower Carboniferous 

 trend nearly north and 

 west. This axis of pi 



Fig. 7. — Map showing general outline of the Narragansett Basin. A-B, 1 



ing through deeper synclines of middle of the area; aa, inlier of grauitite and 

 Cambrian at Hoppin Hill and the Diamond Hill quartz mass on western border; 

 bb, granitic and gneissic inliers near Bristol. Rhode Island ; cc, synclines with 

 coarse conglomerates; oo, synclines along northern border of the basin; dd, 

 gneiss structure in New Bedford area. 



strata to the surface. West of this line the strikes 

 south; east of the line they trend about east and 

 essure, moreover, appears to have been that in 



