1. Lake Michigan Archipelago
Erosion is enhanced where
glacial flow is parallel to
the strike of the formation.

2. Glacial Tunnel Valleys

3. Glacial Tunnel Valleys

4. Lake Michigan Paleolake Levels

5. Lake Michigan Paleolake Levels

6. Lake Michigan Paleolake Levels

7. Lake Michigan Paleolake Levels
9,223 cal. Yrs. ago

8. In the Post-Algonquin era, lake levels
In the Post-Algonquin era, lake levels in the Great Lakes Basin progressively fell due to deglaciation of new, lower outlets to the east.
Eventually, the water level in the Lake Michigan Basin reached its lowest elevation, when drainage shifted to the final outlet at North Bay, Ontario, which flowed eastward along the Ottawa River Valley.

9. This extreme low lake stage is called. Lake Chippewa in the Michigan
This extreme low lake stage is called Lake Chippewa in the Michigan Basin.
Its correlatives were Lake Stanley in the Huron Basin and Lake Hough in Georgian Bay.
Lake Chippewa drained eastward into Lake Stanley, cutting the “Mackinaw channel”.

10. Mackinaw Channel

11. Lake Michigan Paleolake Levels

12. Glacial Isostatic Adjustment (GIA)
A process that continues today!

13. Glacial Isostatic Adjustment (GIA)
Tawas
3 cm/century
Sault Ste. Marie
21 cm/century

14. Isostatic rebound evidence
Nipissing wave cliff
Algonquin 13,000 cal. yrs.
184.4 m
Nipissing cal. yrs.
51.8 m rise in 7000 yrs.
Algonquin wave cliffs

15. The End