390 THE JOURNAL OF GEOLOGY. 



the terraces of the Connecticut have a much greater southward- 

 slope than those on the smaller river, and the depression was 

 not sufficient to reverse the stream. The conditions on the two 

 sides of the trap ridge were not the same. 



To sum up, then, the history of the Farmington seems to 

 have been as follows : Its original consequent course -was south- 

 east on the crystallines and perhaps across the trap ridge at 

 Cook's Gap, from which course it was turned in the Tertiary 

 cycle by a stream whose course was approximately that of the 

 Mill river of to-day. The damming of the valley by the depos- 

 its of the Upper Farmington, and the depression in the north 

 accompanying the ice retreat, reversed the river at Farmington, 

 and it took a new course on the terrace deposits, escaping by 

 the sag in the trap at Tariffville into the Connecticut valley. 



The Quimiipiac. The gorge of the Quinnipiac, already men- 

 tioned several times, seems closely comparable to the gorge of 

 the Farmington. It is not of the Tertiary cycle, and is best 

 referred to the inter -glacial or post-glacial epochs. We should 

 expect the Quinnipiac, instead of turning eastward, to cut 

 through this sandstone ridge, to continue southward along the 

 Mill river valley. Dana^ finds from the heights of the terraces 

 that the drainage of the terrace -building period was not along 

 the Quinnipiac, but along the Mill river, and concludes that the 

 Quinnipiac gorge was obstructed by an ice -dam. I have not as 

 vet studied it enough in detail to do more than express the 

 opinion here reiterated, that this gorge is later than the cycle in 

 which the open sandstone lowland on either side of it was exca- 

 vated. Its topographic form would put it in the cycle which 

 has been called post -Tertiary. 



The Scantic. In the Scantic we have a typical example of 

 a river whose lower course is manifestly of a later date than 

 the upper. In this it is similar to several of our Atlantic rivers, 

 notably those of North Carolina, whose upper courses are on 

 the Piedmont crystallines, being probably established previous 

 to the Cretaceous baselevelling, and whose lower courses stretch 

 ' J. D. Dana. Amer. Jour. Sci., 3d sen, vol. xxv, p. 441. 



