Date of Award
Doctor of Philosophy
Dr. Alan Kehew
Dr. Ardith Hansel
Dr. William Sauck
The objective of the dissertation was to map the glacial geology in southern St. Joseph County, Michigan. The surficial geology was divided into three distinct land systems which are moraine, outwash and fan deposits. The Sturgis Moraine is the most prominent feature transecting the study area from east to west. The topography is further dissected by southwest-trending channels interpreted as tunnel channels.
Thick accumulations of sand and gravel in the study area indicate that glacial meltwater deposition played a dominant role in shaping the landscape. Based on the relative size of the channels and outwash deposits, the largest contribution from meltwater deposition was from the Saginaw Lobe and the least from the Huron-Erie Lobe.
This study also demonstrated that geophysical techniques such as gamma ray logging of domestic water wells, ground penetrating radar and high resolution seismic were useful tools to identify sand, gravel and clay in the subsurface and the thickness of these units. Seven subsurface, gamma ray log markers could be traced throughout the study area. The gamma ray log markers were calibrated to four continuous cores from Sturgis.
The lowest marker, the Sturgis till, lies above a buried soil of possible Sangamon age and is interpreted as a late Wisconsin till. It is present in all wells that are drilled to an adequate depth. Directly overlying the Sturgis till (between markers F-G), is a thin diamicton of similar color but different clay mineralogy (between markers E-F). This thin diamicton is variable in thickness and sometimes there is a facies change from diamicton to coarser grained material at the same stratigraphic level. This sequence is overlain by a sequence of sand and gravel (between markers A and E). This coarse grained sequence is sometimes punctuated by a sequence (or sequences) of higher gamma ray counts interpreted as finer grained units and these individual markers can be traced throughout the study area (markers A-E). Above marker A, is an enigmatic surface diamicton or possible soil horizon.
Nicks, Linda, "The Glacial Geology of Southern St. Joseph County, Michigan" (2004). Dissertations. 3152.