Triassic Fault of Southern Connecticut. 489 



the strata on the north about 2,500 feet, and cites as proof 

 of this the fact that the main sheet outcrops considerably 

 eastwards to the north. Nevertheless, the strata to the 

 north must have sunk, the amount of sinking increasing 

 eastwards, for near Pistapaug Mountain the upper 

 surface of the main sheet is brought close to the horizon 

 of the lower basalt sheet, with the latter on the south, 

 while near the Great Fault the upper and lower basalt 

 sheets are brought nearly opposite each other, with the 



Fig. 4. 



Ant*fioi* 

 Bh«et 



Fig. 4. — Section west-northwest through Pistapaug Mountain. 



lower sheet on the south. The former case corresponds 

 to a throw of about 1,500 feet, the latter to a throw of 

 about 2,500 feet. The displacement of the main sheet to 

 the east on the north is not due to the fault, but to a warp 

 or fold, like that between Pond Rock and Totoket Moun- 

 tain. 



Theoretical Considerations: The Great Fault. 



The Dip of the Plane of the Great Fault. 



Davis 2 believed that the fault plane was nearly vertical, 

 and cited as supporting evidence the fact that the outcrop 

 does not advance to the west in the great anticlinal folds 

 or warps. In another publication 3 he says that the fold- 

 ing probably came before the faulting. If this is the case 

 it is evident that the fault plane could not have been 

 warped by it. However, it will be shown later that part 

 of the movement probably took place before the warped 

 sediments were laid down. 



Am. Jour. Sci. — Fifth Series, Vol. IV, No. 24. — December, 1922. 

 32 



