122 



GEOLOGY OF THE FARRAGAJSTSETT BASIN. 



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which powerful thrusts have acted on the region 

 to the southeastward The granitite of the south- 

 em border in the region of this axis, notably 

 about Fall River, is sheared and rendered locally- 

 schistose by reason of the pressure to which it has 

 been subjected. 



If we continue this Hue still farther southeast- 

 ward, it will be observed that the gneisses of the 

 New Bedford ai-ea exhibit structures roughly con- 

 ^ centric to the Carboniferous strikes on the north- 

 west (see dd, fig. 7). The whole array of sti-uctures 

 points to an older land mass, now submerged, which 

 hes in this southeastern versant of the New England 

 coast From this area the deposits of later times, 

 wrapped about its northern and western sides, 

 I. appear to have been pressed toward the northwest. 



The southern arm of the basin is parallel in 

 structure with the strikes of southern New England 

 westward to the Taconic range. The eastern arm 

 of the basin coincides in trend with the Norfolk 

 I g County and Boston basins in their eastern parts. 

 I These last-named show also, in their inner western 

 extensions, the tendency to become concentric with 

 reference to a point on the southeast. 



The number of great folds in the basin is few 

 (see figs. 8 and 9). Along the line above referred to 

 there are probably not more than four great syn- 

 ^ clines and three inteiwening anticlines. None of 

 these folds appear on earlier sections of this basin 

 (see fig. 10). The great mass of sediments is here 

 thrown into folds having dimensions quite equal to 

 those of the Appalachian folds in Pennsylvania (see 

 fig. 8). From axis to axis of the same kind is a dis- 

 tance upward of 6 miles (see map, fig. 7). With 

 dips often of 45 "^ or more, folds of so great a breadth 

 ar^ commensurable only with a great thickness of 



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