GLACIAL LAKES TAYLOR. 



297 



southern part witli remarkable lidelity. The moraines laid down 

 along the marghi of the lobes at this stage arc roughly concentric 

 with the basins and nearly parallel with their southern shores. A 

 diagrammatic representation of the outline of the ice border at several 

 successive positions is given in figure 1. 



Fig. 1.— Diagrammatic representation of successive positions of ice border. 

 By Frank Leverelt and Frank B. Taj'Ior, 1910. (Data for eastern Wisconsin from Alden and Weidman.) 



COMPLEXITIES OF LAKE HISTORY CAUSED BY STADIAL OSCILLATIONS 



OF ICE FRONT. 



The periodic oscillations in the retreat of the Wisconshi ice sheet 

 introduced a peculiar complexity into the lake history. The stronger 

 or prmcipal recessional morames, called stadial moraines, mark rela- 

 tively long intervals of time — several hundreds, of years, perhaps 

 more than a thousand. Each whole period of oscillation is uivolved 



