GLACIAL LAKE MEMPHREMAGOG 



641 



before the ice had conipletely melted from the valleys. These deposits were 

 therefore forms of aggradation aud not forms produced by degradation. 



Typical eskers, deltas, and kettle-holes are associated with these so-called 

 terraces ■, and eren where these deposits have the characteristic form of river 

 cut terraces, cross-sections as revealed by railway or other cuts show delta 

 structure rather than the structure of alluvial flood-plains. The delta lobes 

 point either down stream or into side valleys, and there are frequently found 

 unfilled portions of the main preglacial valley and of its tributaries below the 

 level of the delta-terrace, between the delta-terrace and the rock walls of the 

 older valley. 



The discussion was participated in by F. G. Clapp. E. D. Salisbury, 

 F. Leverett, Alden, and the author. 



PLEISTOCENE GLACIAL PHENOMENA OF THE BOLIVIAN PLATEAU 



BY W. G. TIGHT 



The paper was discussed by H. F. Eeid and C. H. Hitchcock. 



PREGLACIAL DRAINAGE IN THE MISSISSIPPI VALLEY, A WORKING 



HYPOTHESIS 



BY W. G. TIGHT 



Eemarks were made by F. Leverett and F. Carney. 

 The following paper was read by title : 



GLACIAL FLOWAGE OVER NEW ENGLAND 

 BY J. B. WOODWORTH 



COMPLEXITY OF THE GLACIAL PERIOD IN NORTHEASTERN NEW ENGLAND 



BY- FREDERICK C. CLAPP 



Discussion by F. Leverett, C. H. Hitchcock, Alden, H. M. Ami, and 

 the author. Tliis paper is printed as pages 505-556 of this volume. 



GLACIAL LAKE MEMPHREMAGOG 

 BY C. H. HITCHCOCK 



[Abstract] 



The existence of this lake was first announced at the meeting of the society 

 in 1894.* Recent studies show that it was tributary to Glacial Lake Cham- 

 plain by way of both the La Moille aud Winooski valleys. When the ice 

 filled the Champlain valley to the depth of a thousand feet the impounded 

 water on the east side could have reached the Connecticut basin by way of 

 White river. 



* Bull. fJeol. Soc. Am., vol. 6, p. 400. 



