370 



PLEISTOCENE OF INDIANA AND MICHIGAN. 



stood many miles away to the east or northeast. It was evidently far enough away to allow 

 the heavy seas of Lake Arkona to sweep in from the east to the beach. Here is an ideal oppor- 

 tunity to measure or at least to make a very close estimate of the amount of drift deposited 

 and the work of the ice sheet in the building of a great moraine. 



y* . & gift / m 







I \ ^ \7 ^KiP'" ^ Of /> *> v=, 



*4£ 











^. ^ \ \ '» *^'~ 1 < (W '• '"'er of 



W^ ^ \ .y .^^A^SOr 



Sarnia. s,,.^^ 

 port Hvtronir ^>f> e 



LEGEND 





Moraines deposited Moraines deposited 



on land in water 



(Forestep ice "barriers 



A, B, C, D, E.) 



<l / ,''<£< Detroit g t ..-;.V::v,,... 



A LAKE " / 

 ST CLAIR I 



(Backstep ice barriers 



o, 6, c, ^ e.) 

 CCocations conjectural; 



Figure 6.— Diagram showing lake stages as affected by glacial oscillations on the " thumb" of Michigan. 



SUBMERGED AND MODIFIED ARKONA BEACHES BETWEEN SPRING HILL AND THE OHIO 



LINE. 



From the gateway between Spring Hill and Zion to the State line of Ohio in southeastern 

 Lenawee County the three Arkona beaches are faint and hard to trace, and, indeed, the same 

 character continues throughout Ohio and Pennsylvania and western New York. Detailed 

 descriptions, however, will be confined to the part in Michigan. 



MODIFICATION OF THE BEACHES. 



Between Spring Hill and the Ohio State line the Arkona beaches do not show the characters 

 normal to those in the Saginaw and Black River valleys. The slope southeast of Spring Hill 

 at the Arkona levels bears scarcely anything which could be called a beach ridge ; it carries only 



