392 THE JOURNAL OF GEOLOGY. 



land was elevated and estuarine conditions gave place to fluvia- 

 tile, the Scantic lengthened "mouthward," consequent upon the 

 minor inequalities of the newly made beds. The effect would be 

 substantially the same if the terraces were built by great valley 

 floods, as Dana supposes. In pre -glacial times this river, in 

 common with several other rivers rising on the crystallines and 

 flowing into the Connecticut, had courses of various lengths over 

 the Triassic sandstones, but these old valleys are lost entirely, 

 the later trenches in the terrace deposits being altogether inde- 

 pendent of them. 



Otlier examples. The lower Hockanum, Farmington, Park, 

 and the entire length of many short streams are similar to the 

 lower Scantic, and originated under similar conditions. Stony 

 Brook, a little stream north of Windsor Locks, presents the 

 same features, but with this variation : It is superimposed 

 through a thin layer of drift upon the sandstone, into which it 

 has cut a deep, picturesque gorge. The Hockanum and Farm- 

 ington are also " locally superimposed" in a few places. The 

 Connecticut, also, north of Middletown, although following its 

 pre -glacial valley, has departed in numerous places from its for- 

 mer bed, and has cut down through the valley -filling onto ledges 

 of rock beneath. The water-power at Enfield, Conn., and at 

 Turner's Falls and Bellows Falls, Mass., is the result of this 

 superimposed position. 



Aba?idoned gaps. Many abandoned water -gaps must exist 

 among the hills of the state. Cook's Gap, through which the New 

 York and New England Railroad crosses the trap ridge, three 

 miles west of New Britain, has already been discussed. It must 

 not be confounded with the majority of the other gaps in the 

 trap ridge, which are oblique, break the alignment of the ridge, 

 and are due to faults. 



The New York and New England Railroad in ascending to 

 the eastern plateau passes through Bolton Notch, a few miles east 

 of Manchester. This notch, also, is an abandoned river bed but, 

 as it seems, abandoned at a later date and for another reason 

 than that assigned for Cook's Gap. The drift is very heavy in 



