University of Illinois Urbana-Champaign

Refining the span and rates of deposition of the Glenwood phase of Lake Chicago

Bruegger, Alison Rae

Content Files
BRUEGGER-THESIS-2016.pdf

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https://hdl.handle.net/2142/92666

Description

Title
Refining the span and rates of deposition of the Glenwood phase of Lake Chicago
Author(s)
Bruegger, Alison Rae
Issue Date
2016-07-21
Director of Research (if dissertation) or Advisor (if thesis)
Conroy, Jessica
Committee Member(s)
Curry, B. Brandon
Department of Study
Geology
Discipline
Geology
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
M.S.
Degree Level
Thesis
Date of Ingest
2016-11-10T17:49:11Z
Keyword(s)
  • Lake Chicago
  • Glenwood
  • Illinois
Abstract
The Glenwood phase of proglacial Lake Chicago is its oldest phase, but is the least studied. By developing the and ideas previously published maps by Bretz in the 1930s and studies by Hansel, Mickelson, Thompson and others I will be redefining the span and role of the Glenwood Phase of proglacial Lake Chicago. This task will be completed by using LiDAR DEMs and by obtaining sediment cores proximal to Glenwood phase features and using age models created by AMS C-14 ages. Using this information, in addition to grain size analyses and clay mineral analyses, I will determine the span of the Glenwood phase of Glacial Lake Chicago and indirectly determine the timing of any large meltwater floods and the rate of downcutting of the Chicago Outlet during the transition from the Glenwood phase to its successive Calumet phase. 22 new radiocarbon ages of needles, charcoal and plant marcrofossils were obtained from cores sampled near Glenwood phase features that can still be easily identified. The age models created from the new ages indicate a disturbance in the record at about 15.1 ka. Presently, it is yet debated if the drop from the Glenwood to the Calumet level was due to gradual changes in hydrology or to rapid incision of the Chicago Outlet. If the sediment accumulation rate abruptly decreases simultaneously with the end of the Glenwood phase and subsequently the ~7meter drop from the Glenwood to the Calumet lake levels, that reflects sudden erosion of the Chicago Outlet. The produced age models do present evidence for an abrupt incision near the end of the Glenwood, but a more in depth look at LiDAR evidence proves the Glenwood/Calumet transition to be a bit more complex. A revised history of the Glenwood Phase of Glacial Lake Chicago will help resolve issues of the nature of downstream contributions of Glacial Lake Chicago to the Illinois and Mississippi Rivers, and Gulf of Mexico as well as upstream contributions from the Laurentide Ice Sheet into Glacial Lake Chicago.
Graduation Semester
2016-08
Type of Resource
text
Permalink
http://hdl.handle.net/2142/92666
Copyright and License Information
Copyright 2016 Alison Bruegger

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