692 



WILBUR G. FOYE 



trough may have been bent down between two arched areas on 

 either side, as in Figure i, or the trough may have been faulted down 

 between two upHfted blocks alongside of it, as in Figure 2. While 

 it did not seem advisable to make a final choice between the alterna- 

 tives, the conditions illustrated by Figure i were favored, chiefly 

 because the centripetal dips there shown would give, after general 

 eastward tilting with more or less faulting, moderate dips for the 

 lower strata in the east and stronger dips for the same strata in the 





Fig. 3.— (After Barrell) 



Fig. 4.— (After Barrell) 



^ Trias^ic sediment's and lavas. 



i^ Paleozoic intrusive granit-e-gne>5ses. 



Paleozoic 3edImen^&. 

 Pre-Pateo2oic comple>c gneisses. 



0. Scole in miles, horfzonrol ond.verrical. 10. A-A Depth reached by later cycles of erosion. 



west. Professor Davis states that the field evidence showed an 

 average dip to the east for the basal beds of 20° to 30° along the 

 western border, and seldom more than 20° to the east for the 

 analogous beds where exposed along the eastern.^ His section, so 

 widely copied in textbooks (Fig. 5), is therefore based on Fig. i. 



Professor Barrell, in his well-known study of " Central Connecti- 

 cut in the Geologic Past," gives his conception of the origin of the 

 depression. His idea is illustrated by Figures 3 and 4. A marginal 

 fault of gradual development along the east side of the Connecticut 



^Eighteenth Annual Report, U.S. Geol. Surv., Vol. II, p. 39. 



