F. H. Lahee — Metamorphi&m and Geological Structure. 261 



the middle of the Basin to the walls. Such an increase does 

 occur, however, within three or four miles of the borders, 

 a phenomenon which might be explained by the greater 

 proximity of these rocks to the pre-Carboniferous mass which 

 transmitted, probably in part, the deforming thrust. 



Apparently there are alternating, nearly north-south belts of 

 greater or less intensity, belts which cannot usually be traced 

 continuously. These belts are as follows : (1) along the west- 

 ern border ; (2) Warwick Neck, northern Narragansett Bay, 

 and Providence River in the latitude of East Providence, 

 and the city of Providence ; (3) eastern part of northern 

 Conanicut Island ; (4) Gould Island, Coaster's Harbor Island, 

 Coddington Point, and eastern Prudence Island ; and, (5) 

 Sakonnet River, and eastern coast belt. 



These facts refer to variations along east-west lines. As for 

 north-south directions, only southward intensification of the 

 deformation was noted, and this was in Swansea and, in gen- 

 eral, from the latitude of Prudence Island. 



Conclusions. — From the preceding statements certain infer- 

 ences may be drawn. 



(1.) The high dips of Carboniferous strata resting uncon- 

 f ormably upon the pre-Carboniferous border rocks, the frequent 

 parallelism of strikes of the Carboniferous sediments with the 

 trend of the border, and the diversity of overturn and under- 

 turn relations at the borders, as exhibited by the axial planes, 

 indicate that the forces which operated through the pre-Car- 

 boniferous, whatever their original character, must have been 

 multiple in value and in direction at nearly all places where 

 they encountered the Carboniferous. 



(2.) Within the Basin strata these forces acted in all direc- 

 tions, but with much greater intensity along east-west lines 

 than along north- south lines. 



(3.) In different parts of the Basin the deformation effected 

 by these forces varies in complexity according (a) to variations 

 in the direction and potency of the forces themselves ; (b) to the 

 texture (and therefore rigidity) of the rock affected ; and (c) 

 to vertical position in a given fold. 



(4.) Variations in the deformation, due to variations in the 

 forces, are so distributed that (a) there is a marked increase in 

 the complexhVy of folding and in the amount of compression 

 from north to south ; (b) there are approximately north-south 

 alternating belts of more or less intense deformation ; and (c) 

 within a few miles of the border there is sometimes observable 

 an increase in intensity. 



(5.) Variations in the deformation (only minor folding), due 

 to differences of texture, are important, but local. Finer rocks 

 are more highly contorted than coarser ones. 



