TITLES AND ABSTRACTS OF PAPERS 63 



To Doctor Spencer: The structures referred to in the paper were not built 

 below tide level at a distance from the shore and the intei-vening land cut 

 away, but were erected on the tide water and have simply been buried where 

 they stood. 



To Doctor Clarke : Beaver dams have been found in a salt marsh below low- 

 tide level. 



To Prof. W. M. Davis : The fact that the Nantasket beaches show apparent 

 stability is offset by the fact that in a series of beaches forming the "Point 

 of Pines" at the north end of Revere Beach the shoreward or older beaches 

 are distinctly lower than the one at the present seaward beach, so much so 

 that the spits or ends of the older beaches are now nearly buried by the salt 

 marsh landward and those of the more recent ones are still well above its level. 



To Doctor Goldthwait: The idea of local change in high-tide level because 

 of filling the Bacli Bay in Boston does not appear tenable, since the decrease 

 in the size of the basin would so decrease the velocity of the water entering 

 the opening that not so much would enter as before the arm was closed, and 

 the elevation of the tide would be inappreciable. This may be confirmed by 

 the condition in the North River, where no filling has been done, yet which 

 shows about the same amount of tidal elevation as in the marshes cited in the 

 paper. 



To Professor Johnson : It is not possible that the salt marshes were formed 

 previous to the Nantasket beaches, since if this were true the salt marshes by 

 this time would have ceased to exist as such and have been converted into 

 fresh-water wooded swamps from accretions to their surfaces. The entire 

 character of the flora of salt marshes cut off from the sea by dikes has been 

 changed to the writer's knowledge in a period of less than ten years. The 

 structure of the deposits in existing marshes is so homogeneous that there is 

 no question in the author's mind that the conditions prevailing when the lower 

 beds were formed have been in existence throughout their formation and still 

 persist. The theory of change in the form of tidal surface is not sufficiently 

 elastic to cover all of the cases where historic evidence of subsidence exists, 

 nor are the changes proven to exist sufficiently great to account for the deposits 

 covering some of the objects mentioned in the paper. 



PLEISTOCENE MARINE SUBMERGENCE OF THE CONNECTICUT AND HUDSON 



VALLEYS 



BY HERMAN L. FAIBCHILD 



(Abstract) 



It has long been known that during the waning of the latest ice-sheet New 

 England stood lower with reference to sealevel than at present, but the full 

 amount of submergence has not been recognized. The terraced plains of the 

 Connecticut Valley have generally been attributed to the river, enormously 

 swollen by the glacial outflow. 



In the Massachusetts section of the Valley Professor Emerson recognized the 

 phenomena as due to static waters, and he correctly discriminated the work of 

 the standing water in the open valley from that of the superior glacial streams 

 and lakes, and also from that of the much inferior river flood. His levels for 

 Massachusetts give us a theoretic plane for the sealevel waters. This plane 



