202 H. L. FAIRCHILD POST-GLACIAL UPLIFT OF X. E. AMERICA 



of the southwestern border permitted some rise in the district previous to 

 the waning of the Labradorian sheet. It is therefore probable that the 

 differential uplift shown in the glacial lake beaches of the Michigan and 

 Erie basins is not a record of the earliest nor the total uplift in the west- 

 ern area. The wavelike uplift of the earth's surface following the re- 



FiGUKE 1. — Post-Glacial continental Uplift 



The lines indicate, in feet, the amount of land uplift following the removal of tbe 



Labradorian ice-cap 



moval of the ice-l)urden probably raised the territory southwest of the 

 Michigan and Erie basins, at least in greater amount, before the lake 

 inscriptions were completed. 



The near horizontality of the southwestern stretches of the ancient 

 beaches is not proof of lack of hiiid uplift, l)ecausc some reasonable rela- 

 tion of lake history to rise of land might leave the shorelines quite level. 



