F: II. Lahee — Metamorphism and Geological Structure. 369 



ern northern Conanicut, are stratigraphically lower, and are 

 more metamorphosed, than those of northeastern Conanicut . 

 In northern Aquidneck Island, the rocks of the eastern and 

 western coasts are below those of the central portion of the 

 island ; but the eastern outcrops display more alteration than 

 do the middle and western outcrops. The conglomerate of 

 High Hill Point (Loc. 45, 1 : 11-12), correlated with the Pur- 

 gatory conglomerate of southeastern Aquidneck, is more highly 

 sheared than the latter. Finally, the arkose and associated 

 rocks, which are presumably low in the series, are scarcely 

 metamorphosed on the eastern coast of Mackerel Cove (Loc. 

 22, D : 14), and are not severely crushed on Sachuest Neck 

 (H:14). 



These and other comparisons which might be made, compel 

 us to believe that the degree of metamorphism is not inti- 

 mately dependent upon stratigraphic depth. As in the case of 

 texture, this may be on account of the great thickness of the 

 overlying cover during the process of metamorphism, by virtue 

 of which differential values were reduced. 



Relations Between the Degree of Metamorphism and the 

 Intensity of the Folding. 



In describing the structural geology, we discussed strikes, 

 dips, pitch, axial planes, relative number of folds across the 

 Basin, and minor folding.* The degree of metamorphism 

 may now be studied with reference to each of these topics. 



Strikes. — The most regular strikes were said to occur in the 

 western coast belt on Boston Neck and northward to Barber's 

 Height (Loc. 9, B-C : 12) and in northern Conanicut Island ; 

 and the fact was explained by the inference that the action of 

 the maximum component of the forces of deformation was 

 here predominant. These are also districts of almost uni- 

 formly high metamorphism. 



In the western coast belt between Hamilton (Loc. 8, B : 11) 

 and East Greenwich, and on Prudence Island, strikes are 

 somewhat variable. The degree of metamorphism is constant 

 and is high in these areas. 



Elsewhere strikes are less regular and, coincidently, varia- 

 tions in the metamorphism within short distances are greater. 



Thus, there seems to be a correspondence between the 

 degree of regularity in the strikes of the major folding, on the 

 one hand, and the intensity of the metamorphism, on the 

 other hand. 



Dips. — The degree of metamorphism is more often high 

 than low where dips are steep ; but locally it may be high in 

 outcrops with a gentle dip. 



* This Journal, last number, pp. 256-259. 



