GLACIO-LACUSTRINE STACK 



637 



Fig. 526. The beginning of the Great Lakes. The ice still occupied the 

 larger parts of the present lake basins. (U. S. Geol. Surv.) 



Fig. 527. A luu-r stage- in the development of Lakes Chicago and Maumee. 

 Hit- ix- has n-trt-ated, and the outlet of Lake Maumee has been shifted. (U. S. 

 Geol. Surv.) 



