508 PROCEEDINGS OF COLUMBUS MEETING. 



silt to fill them : so that on a temporary advance it is easy enough to see how even 

 in an open valley all sorts of deposits may take place in rapid succession. 



The bearing of these discoveries concerning the elevated shell-beds in the glacial 

 deposits of England is very significant with reference t<> the general theory of an 

 interglacial period. In fact, the principal necessity for the supposition of an inter- 

 glacial period in England disappears with this explanation. So far as theevidence 

 goes, the glacial period in England seems to have been a -rand unity, characterized 

 only by minor episodes and by periods of the prevalence, first, of the ice moving 

 from Scandinavia and the Welsh mountains and, secondly, of that which proceeded 

 more slowly from the sources of the great Irish-sea glacier. There is now left no 

 sufficient reason for interposing a vast interglacial subsidence between the preva- 

 lence of the ice coming from the first centers mentioned and that coming from the 

 other two. The upper till ami the lower, so far as found in England, is probably 

 the product not of two distinct glacial periods, hut of minor episodes in a single 

 period. 



The Society then took a recess and visited the Columbus ( !lub in accep- 

 tance of the invitation extended the previous day by the colleagues of 

 Dr. Edward Orton. 



At •'! o'clock p. m. the Society reassembled. 



The first paper of the afternoon, read by W J McGee in the absence of 

 the author, was entitled — 



THE CHAMPLAIN sUBMEPmONCE. 



BY WARREN l" I'll AM. 



(Abstract.) 



Marine fossils in beds overlying the glacial drift prove that the northeastern part 

 of North America stood lower than now in the Champlain epoch — that is, the time 

 of departure of the last ice-sheet. This depression, which seems to have been pro- 

 duced by the vast weight of the ice, was bounded on the south approximately by 

 a line drawn from near the city of New York northeastward to Boston and onward 

 through Nova Scotia. When the ice-sheet was being withdrawn from this region 

 the country south of this line stood somewhat higher than now, as is shown by the 

 channels of streams that flowed away from the melting ice and ran across the 

 modified drift plains which form the southern shores of Long island, Martha's 

 Vineyard, Nantucket and cape Cod. A subsequent depression of the land there* 

 continuing perhaps uninterruptedly to the present time, has brought the sea into 

 these old river courses; hut north and northwest of this line the land at the time 

 of recession of the ice-sheet was lower than now and the const and estuaries were 

 more submerged by the sea. Fossiliferous beds of modified drift, supplied from 

 the melting ice-sheet and resting on the till, show that the vertical amount of the 

 marine submergence when the ice-sheet disappeared was 10 to 25 feet in the vicinity 



