M PROCEEDINGS OF COLUMBUS MEETING. 



the Lafayette-Reynosa by a strong unconformity representing erosion many times, 

 perhaps many hundred times, greater than that of the post-Columbia period. 

 Throughout the greater part of the province there is a still mure noteworthy 

 unconformity below the Lafayette; but this unconformity lias not yet been so 

 clearly recognized in Texas, where indeed there is reason for believing it to be of 

 diminished magnitude. 



Tliis paper forms pages 219-230 of this volume. 

 The next communication was entitled : 



A REVISION ANh MONOGRAPH OF THE GENUS CHONOPHYLLJJM. 



BY \V. II. SHERZER. 



Remarks were made by Alpheus Hyatt. The paper is published as 

 pages 253-282, with plate 8, of this volume. 



Announcements were made by the President and Secretary, and the 

 Society adjourned for the noon recess. 



The Society reassembled at 2 o'clock p. m. and listened to a paper 

 read, in the absence of the author, by W .1 McGee: 



RELATIONSHIP OF THE GLACIAL LAKES WARREN, ALGONQUIN, IROQUOIS AND 



HUDSON-CHAMPLAIN. 



BY WAEREN UPHAM. 



| Abstract. 



These names, excepting the last, which has not been before used, were proposed 

 by Professor J. W. Spencer, in 1888, for the must important and distinctly defined 

 stages of the formerly larger bodies of water that have occupied the basins of the 

 great Laurentian lakes since the deposition of the drift. Their shore lines, high 

 above the present lakes, are clearly marked by beach ridges and eroded cliffs. 

 Large portions of the old beaches and of the enclosed lacustrine tracts have been 

 mapped by the geological surveys of Ohio and Wisconsin and by Professor Spencer 

 and Mr. Gilbert, both of whom have recently made important contributions to the 

 discussion of the history of these lakes, concerning which also I. yell. Chapman. 

 Fleming, Whittlesey, Newberry, ( Maypole, and others had written earlier. Spencer 

 holds that these bodies of water were held by harriers of land, so far as they were 

 true lakes, while he would refer some of the old shove lines to depression of the 

 land so low as to permit them to be formed by the sea. Mr. Gilbert, on the other 

 hand, attributes these ancient lakes to the harrier of the ice-sheet during its reces- 

 sion at the close of the Glacial period, their changes in area and their reduction 

 from higher to lower levels being due to the gradual uncovering of the land from 

 the ice by which it had been enveloped, opening thus successively lower outlets. 



