Dissertation Defenses

Doctoral Dissertation Announcement

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Candidate: Brian Bird

Degree of: Doctor of Philosophy

Department: Geosciences

Title: Glaciotectonic Deformation along the Valparaiso Upland in Southwest Michigan

Committee:
Dr. Alan Kehew, Chair
Dr. William Sauck
Dr. Ronald Chase
Dr. Andrew Kozlowski

Date: Wednesday, March 17, 2010 3:00 p.m. - 5:00 p.m.
1122 Rood Hall

Abstract:
Glaciotectonic deformation has been observed and analyzed across parts of the Valparaiso, Kendall, and Inner Kalamazoo Moraines in southwest Michigan, USA. Deformation structures such as folds and faults have been analyzed using techniques typically used by structural geologists. The fabric of elongated clasts in the surficial diamicton was also measured and analyzed. The structures are consistent with simple shear, horizontal compressional stresses and pure shear. Evidence of clastic dykes as the result of hydrofracturing is also observed. A series of drumlin fields exists along the western boundary of the study area. Direct investigation of the deformed sediments was conducted at a gravel pit in one of these drumlins. Lacustrine derived sediments with areas of coarse sand and gravel dominate the stratigraphy of the study area. The rheology of the sediments is responsible for the deformation observed as the Lake Michigan Lobe (LML) readvanced across the area to the Kalamazoo Moraine. The LML readvanced into a proglacial lake system impounded between the ice margin and the Kalamazoo Moraine. The fine-grained lacustrine sediments, restricting the flow of subglacial water, increase the pore water pressure, which in turn decreases the shear strength of the sediments promoting the deformation of these sediments. The advancing ice deforms sediments in two stages, proglacially along a décollement at the ice margin, then subglacially as ice overrides the sediments.