Todd Thompson
Geological Research at the IGS

Middle-Holocene (ca. 6500 to 3500 years ago) lake-level change of ancestral Lake Superior, Huron Mountains, Upper Michigan

Status Start Date End Date Locations
completed Feb 1, 2014 Feb 1, 2015 Outside Indiana
Director: Henry Loope
Other Researchers: Todd Thompson John Johnston, Ken Lepper
Funding: Huron Mountain Wildlife Foundation
Issue: A detailed paleohydrograph for ancestral Lake Superior spanning the early and middle Holocene (ca. 9000 to 4500 years ago) has not been produced. Large changes in lake level occurred during this time and the relative roles of glacial isostatic rebound and climate are not entirely known. This information is critical for inputs to glacial isostaic rebound models and provides a long-term perspective on the influence of climate on lake-level fluctuation.
Objective: The primary objective is to determine the age and elevation of foreshore sediments associated with beach ridges in a strandplain located in the Huron Mountains, Upper Michigan. These data will be used to generate a relative paleohydrograph for the site covering 3000 years, from roughly 6500 to 3500 years ago.
Approach: Twenty-five vibracores will be collected in order to determine the stratigraphy and elevation of foreshore deposits associated with each beach ridge. Optically stimulated luminescence (OSL) dating will be used to determine the age of foreshore or eolian sediments at select beach ridges (five ridges in total). Each site is to be surveyed with an optical transit and the elevation is determined relative to the International Great Lakes Datum of 1985.
Products: Loope, H.M., Johnston, J.W., Thompson, T.A., and Lepper, K., 2015. Analysis of Middle-Holocene Lake-Level Change of Ancestral Lake Superior, Huron Mountains, Upper Michigan: Indiana Geological Survey Open-File Study 15-01.
Benefits: Understanding the timing and magnitude of past lake-level change of the Upper Great Lakes (Lakes Superior and Huron-Michigan) allows historical observations of lake level to be placed in a broader geologic context. These data permit evaluation of the relative role of glacial isostatic rebound and climate on lake-level change. This work also adds to the understanding of long-term behavior of Great Lakes coastal systems which provides a framework for modern processes and management of Great Lakes coastlines.
Publications:

Preliminary analysis of Middle Holocene lake-level change of ancestral Lake Superior, Huron Mountains, upper Michigan

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