378 THE JOURNAL OF GEOLOGY. 



Triassic times, during which the contorted crystallines were worn 

 down to a comparative level; second, a cycle of subsidence, de- 

 position and volcanic outburst, during which the sea entered the 

 crystalline trough, and the Triassic conglomerates, sandstones and 

 shales were deposited with the intercalated layers of lava; third, 

 a long cycle of elevation, folding, faulting and erosion, during 

 which the sedimentary beds were elevated — tilted into the present 

 faulted monocline, and this constructional surface worn down to a 

 baselevel of erosion in late Cretaceous times. Each of these 

 cycles probably represents the sum total of several subordinate 

 cycles. There was, fourth, a post -Cretaceous uplift inaugurating 

 a period of erosion lasting through Tertiary times and resulting 

 in the formation of valleys in the hardest rocks, and a lowland 

 approaching baselevel on the Triassic sandstones and shales; 

 fifth, a probable late or post -Tertiary uplift, when the valleys 

 were deepened and the lowlands trenched — obscure in Connec- 

 ticut, but well shown farther south; sixth, the land, near the 

 coast at least, is now slightly lower than it has been in the not 

 remote past, as is shown by the fjords. 



With the changes of the physical geography clearly in mind, 

 the rivers of Connecticut may now be examined in respect to 

 their conditions of origin, the number of cycles through which 

 they have lived, and the approach they have made to mature 

 old age. But at the very outset a serious difficulty is encountered, 

 for the geological structure of the state is nowhere well described, 

 nor have topographic maps of all the districts yet been issued. 

 Since the structural details are to some extent unknown 

 it is unwise in many cases to attempt more than tentative 

 conclusions. Several of the problems to be presented cannot 

 be considered as settled. Considerable progress toward a final 

 settlement will have been made, however, if the conditions of 

 the problems are made clear, various hypotheses suggested, and 

 the attention of workers in this field called to these questions. 



Early drainage. Of the drainage of Connecticut during 

 Jurassic and Cretaceous times very little can be said. It is not 

 even known whether it was consequent upon the Jurassic tilting 



