Date of Award

8-2008

Degree Name

Master of Science

Department

Geosciences

First Advisor

Dr. Alan Kehew

Second Advisor

Dr. Mohamed Sultan

Third Advisor

Dr. Andrew Kozlowski

Access Setting

Masters Thesis-Open Access

Abstract

Surficial mapping, borehole analysis, and ground penetrating radar surveys are used to reconstruct conditions leading to the formation of tunnel valley and esker networks within the Dowling 7 .5 minute quadrangle. The relationship between tunnel valleys and eskers has important implications on the subglacial hydrology beneath the Saginaw Lobe of the Laurentide Ice Sheet.

Surficial mapping reveals northeast-southwest trending tunnel valleys, some containing eskers of the same orientation, in hummocky topography mapped as the Saginaw Kalamazoo Moraine. A borehole hole drilled through one such tunnel valley and esker pair reveals sand and gravel fining upwards to fine sand. Stratigraphy suggests that the subglacial tunnel persisted for a long period of time with flow waning. A sandy diamicton capping the esker and other hummocky topography throughout the study area is interpreted as meltout till. The ground penetrating radar surveys show features such as normal faults, slumping beds, and buried hummocks, which are consist with downwasting of stagnant debris rich ice. This corresponds to models which postulate the Saginaw Lobe was in state of stagnation and retreat as ice movement to the north began shifting to the Huron-Erie and Lake Michigan Lobes.

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