694 WILBUR G. FOYE 



depression tilted the accumulating sediments toward the east and 

 quickened the streams. Later smaller faults broke the trap flows 

 and initiated the present topography (Fig. 4).^ Professor Barrell 

 supported his conception by the one statement that "the dominant 

 segregation of conglomerates near the eastern margin is even more 

 marked in the beds above the lava flows than in those below, and 

 this greater average coarseness of the upper sediments indicates 

 the intermittent regrowth of the mountains whose perennial waste 

 kept supplying material for the basin."^ 



For reasons which will now be briefly stated the writer believes 

 that Barren's diagram represents most accurately the structure of 

 the Connecticut depression during the Triassic. 



1. A warping movement that distorts a peneplain surface with- 

 out faulting must proceed very slowly. It is difficult to imagine 

 that such a movement would revive the streams flowing into the 

 Connecticut basin and cause them to transport bowlders of such a 

 size as may be found not only in the edge but also toward the center 

 of the trough. Cobbles 6 or 8 inches in diameter are found near 

 the center of the valley, north of Meriden.^ 



2. Arkoses are common along the western border of the basin 

 but are almost lacking along the eastern border, whereas coarse 

 conglomerates are common along the eastern border but are seldom 

 found along the western border. The inference is that the streams 

 from the west were carrying the exfoliation products of a desert 

 topography, but those from the east were carrying bowlders snatched 

 from the wall of a growing fault scarp. 



3. A consideration of the geometry of the geosynclinal hypothesis 

 of Davis and the fault-monoclinal hypothesis of Barrell leads to 

 conclusions which are more favorable to the latter. In Figures 6 

 and 7, let W represent the width of the Connecticut Valley. In 

 northern Connecticut this width is approximately 21 miles; at 

 Middletown it is 17 miles, or, if the Pomperaug Valley area is 

 included within the larger basin, the width becomes 33 miles. Let 

 D represent the depth of sedimentation within the basin. Compe- 



» Bulletin No. 23, Conn. State Geol. and Nat. Hist. Survey, p. 28. 



'Ibid., p 29. 



3 Eighteenth Annual Report, U.S. Geol. Surv., Part II, p. 33. 



