THE ACADIAN TRIASSIC 259 



Devonian granite, and in part by pre-Cambrian slates (the Meguma 

 series) and other metamorphic rocks (the pre-Cambrian complex 

 of New Brunswick). The Connecticut Valley area is underlain 

 by gneisses and schists, the New Jersey area by gneisses and some 

 Paleozoic sediments, and the Richmond area by gneisses and 

 granites. A theory which accounts for the structure of the Newark 

 beds must therefore suit the various basement rocks. 



Davis, 1 in studying the Connecticut area, reached the con- 

 clusion that the origin of the monoclinal fault structure was the 

 slipping of blocks of the underlying crystalline rocks on each other 

 along cleavage planes. As pointed out above, although the Con- 

 necticut area is underlain by gneisses and schists, the other Newark 

 areas are not. Suitable cleavage planes would therefore not be 

 expected in the other areas. 



In the Minas Basin region, the crystalline rocks are several 

 thousand feet below the base of the Triassic. Furthermore, the 

 planes of slipping in these crystallines are parallel to the main struc- 

 tural lines of the formation. These lines run at an angle to the 

 axis of Minas Basin, as is seen in the nearest exposures of the 

 crystallines (the Meguma, or Gold-bearing series). The theory 

 proposed by Professor Davis does not seem, therefore, to apply to 

 the Acadian area. 



Hobbs 2 considers that Professor Davis' theory does not suit 

 the facts in the Connecticut Valley or in the Pomperaug area. 

 For the latter area, Hobbs proposes another theory to account for 

 the peculiar system of quadrangular block-faults. As this detailed 

 faulting is not typical of all the Newark areas, the theory is of 

 limited application. 



Professor Barrell 3 has recently ascribed the origin of the Con- 

 necticut Valley Triassic area to the gradual development of a fault 

 on the east side of the geosyncline, contemporaneously with the 



1 W. M. Davis, "The Structure of the Triassic Formation of the Connecticut 

 Valley," U.S. Geol. Surv., yth Ann. Rept., 1888, pp. 486-89. 



2 W. H. Hobbs, "The Newark System in the Pomperaug Valley, Connecticut," 

 U.S. Geol. Surv., 21st Ann. Rept., Part 3 (1901), pp. 122-33. 



3 J. Barrell, "Central Connecticut in the Geologic Past," Proc. Wyo. (Penn.) 

 Hist, and Geol. Soc, XII (19 12). 



