226 J. W. SPENCER SUBMARINE VALLEYS 



Glacial elevation did not exceed from 200 to 450 feet above the present 

 level. 



Appendix 



As Mr Lindenkohl, of the Coast Surve}^ had previously made the 

 studies of the submarine valleys along the coast, I submitted this paper 

 to his consideration, in reply to which I received the following commu- 

 nication, with permission to use it, and as it brings out one or two points, 

 T take the liberty of adding it to the foregoing paper: 



' ' Washington, D. C. , December S6, 1902. 



" Dear Sir: I have perused with great interest your paper on 'Submarine val- 

 leys," etcetera. . . . Your statements accord very well with my recollections, 

 and your conclusions seemed to have been reached by sound logical reasoning. 

 . . . Are there no indications of a submerged Connecticut river, a river in which 

 Professor Dana was greatly interested ? Some years ago I traced a river channel 

 from the entrance of Narragansett bay to two-thirds the way from Gay head to 

 Block island, where a terminal moraine is incised by a deep gorge (216 feet). This 

 channel disappears in a bar of about 165 feet below sealevel. Allowing 15 feet for 

 effective depth of bar, these figures indicate the subsidence of about 150 feet since 

 the Glacial period. There is a similar submerged channel between Block island 

 and Montauk point. 



" The channel of the Narragansettan river passes through an inner or later mo- 

 raine, stretching to the northern shore of Long island. A branch of the Narra- 

 gansettan river enters the sound. I have no doubt that more indications of sub- 

 merged channels will be found wherever they are not obliterated by glacial drift 

 or other sediments when a careful search shall have been made. The fact of the 

 existence of similar channels from the European side of the Atlantic appears to 

 me to favor the theory of an accumulation of water in the northern part of the 

 ocean" (meaning a change of ocean level b}' transference of the waters, as shown 

 in the subsequent letter) "rather than the subsidence of the land, but I assume 

 that your close investigations into the geological structure of the Antilles has en- 

 enabled you to correctly explain the physiographical features of the adjacent sea 

 bottom. 



" Yours very truly, A, Lindenkohl." 



So far as the information is before me, it seems that the Connecticut 

 river was a tributar}^ to that from Narragansett bay, as I know of no 

 buried channel across Long island, nor is there sufficient indentation 

 or corresponding cove in the edge of the continental shore, as is the case 

 in front of Narragansett h2i\. 



With regard to the causes of change of level of land and sea, I do not 

 exclude Mr Lindenkohl's suggestions that part of the change may have 

 been due to the movements of the oceanic waters, as there are many 

 observations which sustain the hypothesis; yet at other points the de- 

 formation of the land is independent of the ocean level and in })art has 

 given rise to the changes. 



