120 



GEOLOGY OF THE Is T ARRAGANSETT BASIX. 



mainly to do, the acquisition of secondary characters in the strata is very 

 closely related to the degree of tilting which the}'- have undergone. Aside 

 from one or two narrow belts of dynamic metamorphism, accompanied by 

 the development of new minerals, the alteration is generally limited to the 

 production of cleavages and joint structures. It is on account of this lesser 

 degree of alteration and the identifiable condition of plant remains that 



Fia. 6. — Map showing distribution of ruetauiorpkoserl Carboniferous rocks. 

 A, Narraiiansett Bay area of maximum ruetamorphisiu ; B, Winneconnetarea; 

 C, Morrill's area in Norfolk County Basin. 



this portion of the field affords the best ground in the Carboniferous basin 

 for determining the succession. 



In the subsequent pages the attempt to establish certain rock groups 

 in a typical area will be followed by a description of the extension of the 

 rocks over the remaining field. Before describing' the rocks, however, I 

 shall discuss the facts relating to the general structure and the boundary of 

 the basin. 



