342 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



The Connecticut below Turners Falls, Mass. My field notes 

 here are hardly of sufficient detail to serve as the basis of a sketch map. 

 Suffice it to say, that for several miles down the river from Turners 

 Falls to the Fitchburg railroad bridge in Montague, there are numerous 

 examples of defended terraces, fully confirming the principles already 

 illustrated and suggesting some new ones, to which I hope to return in 

 a later essay. But concerning a stretch of the river southward from this 

 section, Emerson has written as follows : " The subsidence of the waters 

 of the Connecticut lakes to the present Connecticut river was very rapid. 

 ... As a result, one goes down ■ — through the whole length of the 

 Montague Lake, which was well filled up in the flood time, except in its 

 southern portion — by a great scarp to the series of erosion terraces of 

 the modern river, the highest of which rise but a few feet above the level 

 of the flood plain" (725). 1 



This conclusion as to the " very rapid " change of level by which the 

 erosion of the present valley floor in the former drift filling was initiated 

 seems to be based entirely on the feature here noted, namely, the great 

 scarp by which descent is made from the high drift plain to the low ter- 

 races of the modern river. The conclusion is so directly opposed to the 

 one that I have reached in the course of the present study that it has 

 been considered with some care. In the end I am led to doubt its 

 validity for the following reasons. 



First, the occurrence of the single great scarp does not necessarily 

 prove that the river suddenly cut its channel down from the level of the 

 "lakes" to about that of the modern flood plain. The single great 

 scarp is here, as in other examples of the same kind, perfectly consistent 

 with a leisurely degradation by the river, and with the production of 

 numerous flood plains during the degradation, provided only that the 

 modern swinging of the river has been greater than the swinging at 

 higher levels, whereby all remnants of the earlier flood plains shall have 

 been destroyed. It has been shown that this is habitual with a number 



1 The stratified drift deposits of the Montague and other basins are interpreted 

 as lacustrine by Emerson. Their fine texture and even stratification certainly 

 indicate deposition in quiet water, but in the absence of any well-proved barrier 

 between the basins of the middle Connecticut valley and the sea, there seems to be 

 a possibility that the water bodies were of the nature of narrow-mouthed bays, 

 with surface at sea-level, rather than normal lakes, with outflowing streams de- 

 scending to sea-level. 



If the reader should consult the original text of this reference, he should note 

 that the first line of page 726 seems to have been misplaced from the bottom of 

 that page. 



