Direction and Dip of the Strata. 



271 



Direction, Dip, and Thickness of the Strata. 



Graywacke is celebrated in other countries for the irregularities of 

 its stratification, and the tortuosities of its slaty varieties. Nor is 

 this rock in New England lacking in these characteristics. The ob- 

 server will be satisfied, after an extensive examination, that the pre- 

 dominant direction of the strata of this rock is not far from east and 

 west, and the dip northerly, generally approaching to 45 degrees. 

 But he will be surprised to find in the western part of the principal 

 deposit, viz. from Randolph to Providence, and so on to the southern 

 extremity of Rhode Island, that the direction of the strata is nearly 

 north and south, and the dip east. The following table exhibits the 

 dip and direction of this formation in various places, as I find them 

 in my notes. 





Direction. 



Dip. 



1% IT n 11 



Mansfield, 



N.W. and S.E. 



45° N.E. 



Berkley, .... 



JN.Jii. ana o. W. 



TVT TXT 



IN. W. small. 



Attleborough, (west part,) . 



North and .South. 



East, small. 



do. (center,) . 



do. 



50° West. 



Walpole, .... 



tvt TTi J" CJ TIT 



N.tj. and b. W. 



rrv°i n a«at tit 



50 to 60 N. W. 



Pawtucket, (Grajnvacke Slate,) 



S. 20° West. 



70° easterly. 



From Providence to Warren, 







Rhode Island. 



N. and South. 



45° East. 



Seekonk, .... 



do. 



10° East. 



Portsmouth, R. I. (Slate,) 



N.E. and S.W. 



S.E. 40° to 90°. 



Newport, R. I. near Fort Ad- 







ams, (Slate,) 



N. and South. 



5°tol0°easterly. 



do. South part, (do.) 



E. and West. 



Various. 



do. Southeast part (do.) 



N. and South. 



60°to70°West. 



do. do. Purple Quartz 







Rock, 



N. and South. 



80° East. 



West side of Narraganset Bay 







(Slate,) 



N. and South. 



10° to 15° East 



Middletown, R. I. Blue Quartz 







Rock, 



N. and South. 



E. 80° East. 



do. do. Amphibolic 







Aggregate, 



N. and South. 



60to 70° West 



Between Warren and Bristol, 







Rhode Island, 



E. and West. 



10to20°North. 



