GLACIAL WATERS IN THE LAKE ERIE BASIN 



II 



southwest ward along the ice margin to the open lake waters in the 

 western part of the Erie basin, with ultimate overflow to the 

 Mississippi. This brings us to the matter which is the special 

 subject of this writing — the history of the glacial waters, the 

 stream phenomena and the lake records. 



(4) The lake waters. As the ice body melted away, obliquely, 

 from the land slope the lake waters crept in along the ice margin 

 and occupied all the open space below their level. Beaches, as 

 gravel bars and spits, and delta fillings mark the borders of these 

 glacial lakes, which followed the waning ice front and expanded 

 to vast extent. Before we can fully and properly describe the 

 stream channels and the greater glacial lakes and their effects it is 

 necessary to discuss some other features, specially the moraines 

 and the local glacial lakes which occupied at various levels the 

 valleys sloping toward the glacier. 



ICE MARGINS: MORAINES 



The glacial period probably included several epochs of ice 

 invasion with intervening epochs of ice retreat or deglaciation. In 

 western New York we have accepted evidences of only the last epoch 

 of glaciation, called the Wisconsin. All the phenomena described 

 in this paper relate to or are connected with the waning and disap- 

 pearance of the Wisconsin ice sheet, and particularly of the Erian 

 and Ontarian lobes. 



The pauses in the recession of the ice front are marked by termi- 

 nal accumulations of marginal drift, or recessional moraines. The 

 series of recessional moraines for the whole Erie basin are given, 

 somewhat theoretically, in Leverett's Monograph XLI. The corre- 

 lation of the later moraines in western New York with those across 

 the basin, in Ontario, Can. has not yet been made, although essen- 

 tial for full knowledge of the glacial lake history. The succession 

 and altitude of the glacial waters were determined by the successive 

 positions of the ice front, acting as a barrier, at certain critical 

 localities. As any possible mapping now of the correlated or cor- 

 responding moraines in Michigan, Ontario and New York would be 

 conjectural and probably misleading no attempt is here made to 

 map or represent them. 



The terminal moraine, which marks the greatest expansion of the 

 Wisconsin ice body in the Lake Erie basin and western New York, 

 lies near Olean and Salamanca. From this locality it extends both 

 southeast and southwest into Pennsylvania, showing that the ice 

 front there had an indentation or reentrant angle. 



