Geologic Mapping of the Bronson North and Bronson South 7.5-Minute Quadrangles, Branch County, Michigan
Date of Award
Master of Science
Geological and Environmental Sciences
Dr. Alan E. Kehew
William Sauck, Ph.D.
Robb Gillespie, Ph.D.
Cuesta, geology, quaternary, glaciation, geophysics
Masters Thesis-Open Access
This study contributes to a better understanding of the glacial history of southwest Michigan through detailed surficial geologic and bedrock topography mapping within the Bronson North and Bronson South Quadrangles in Branch County, Michigan. This project was supported during the summer of 2017 by the USGS EDMAP program in conjunction with the Michigan Geological Survey. Hand-auger borings, grain size analysis tests, passive seismic depth-to-bedrock measurements, and ground penetrating radar transects were collected for this study. There are 350 feet of bedrock relief from west to east across the quadrangles, including a bedrock cuesta of Mississippian Coldwater Shale. This cuesta underlies an area of streamlined drumlins in the northern portion of the study area, which become more diffuse to the west of the study area. Drumlins mapped in the area are composed of diamicton occurring at elevations above 900ft (274m) in the northern quadrangle. Coarse-grained outwash occurs in swales between the drumlins. The southern quadrangle is predominantly composed of coarse-grained outwash, which exhibits a hummocky topographic surface. Surficial sediments in this upland were deposited within a braided stream system during deglaciation. Glaciofluvial sediments within these quadrangles were deposited by meltwater streams derived from the Huron-Erie and Saginaw Lobes of the Laurentide Ice Sheet during final retreat approximately 19,000 cal yr.
Backhaus, Karl John, "Geologic Mapping of the Bronson North and Bronson South 7.5-Minute Quadrangles, Branch County, Michigan" (2018). Masters Theses. 3432.