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GLACIAL MELTWATER LAKES

A. Introduction

Learning outcomes - You should be able to:


B. Wisconsin Glacial Lakes link icon: Wisconsin relief

Glacial Lake Oshkosh

  • Green Bay Lobe dammed northward-draining Fox River Valley

  • ~5,000-10,000 km2 at largest

  • lake levels controlled by:

    • extent of Green Bay Lobe

    • isosatic adjustment

  • outlets:

    • Wisconsin River to the southwest

    • several outlets to north or east draining into Lake Michigan

  • 3 sets varved silt-clay lake sediment Link: photo of glacial Lake Oshkosh sediment - Hooyer (ed.) 2007 WGNHS

    • lake filled at least 3 times

    • 20-40 ft thick;

    • 32-257 rhythmites

       

 

Map: glacial Lake Oshkosh

 

Diagram: Lake Oshkos stratigraphy.  After Hooyer WGNHS 2007

Glacial Lake Wisconsin

  • initially existed ~19,000 YBP; drained & refilled several times

  • dammed southward-flowing Wisconsin River

    • Green Bay Lobe dammed drainage to east

    • Baraboo Hills bounded drainage to south

  • lake levels controlled by:

    • extent of Green Bay Lobe

    • isosatic adjustment

  • outlets:

    • northwest to East Fork Black River

    • southward to Wisconsin River

  • lake basin:

    • broad, sandy-silty plains; sediment up to ~100 m thick

    • Lewiston sub-basin

      • dammed by Johnstown moraine to west, Green Bay Lobe to east, Baraboo Hills to south

      • helped form present-day Lake Wisconsin

 

map glacial Lake Wisconsin

 


C. Glacial Lake Agassiz link: map of glacial Lake Agassiz link: map of glacial Lake Agassiz

Formed about 11,700 14C YBP

Size

Drainage

Impact on climate


D. Evolution of the Great Lakes link: diagrams showing evolution of Great Lakes  link: diagrams showing evolution of Great Lakes

E. Glacial Lake Missoula   link: map glacial Lake Missoula  link: diagrams showing evolution of Great Lakes

Ice-dammed lake in western Montanna


F. Summary

Formation of ice-marginal lakes

Wisconsin glacial lakes

Glacial Lake Agassiz


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©Karen A. Lemke: klemke@uwsp.edu
Last revised March 8, 2017