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Mapping the Ice Age deposits of Jefferson County

Libby IvesLibby Ives, a research assistant at the Survey and a PhD student at UW–Milwaukee, is one of the Survey’s newest members. With the Survey’s Elmo Rawling, Libby is mapping the Pleistocene (Ice Age) geology in Jefferson County. Libby says, “The two most interesting glacial features in this area are drumlins and Glacial Lake Scuppernong.”

Drumlins of the Green Bay Lobe in Wisconsin

Drumlins of the Green Bay Lobe in Wisconsin.

The most prominent and charismatic landforms in northern Jefferson County are the drumlins, elongated cigar-shaped hills, of the Green Bay Lobe. The glacial deposits in this region seem to be quite thin in some areas, meaning that the bedrock is near the surface. This may have influenced the orientation and distribution of the drumlins.

Ives said, “We’re really excited about the opportunity to coordinate with the planned bedrock mapping project of Jefferson County to better understand how local bedrock geology influenced Wisconsin glaciers and the sediments they deposited.” (Bedrock geologist Esther Stewart will begin a 2-year mapping project in the county in 2019.)

Glacial Lake Scuppernong probably formed following the retreat of the Green Bay Lobe at the end of the last ice age. That lake is thought to have covered most of Jefferson County at one point or another. Mapping Jefferson County will let Rawling and Ives focus on the history of this glacial lake, which is not something that’s been worked on in detail yet.

Libby said, “In addition to understanding Wisconsin’s geologic past, Pleistocene (sometimes called surficial) geologic maps are essential to understanding and managing our water, aggregate, and natural resources.”

Ives was born and raised in Waukesha, Wisconsin. She got a B.S. in earth science from Northern Michigan University and an M.S. in geology (with a focus on glacial geomorphology) from Iowa State University. She is currently a Ph.D. student in the Department of Geosciences at UW–Milwaukee, focusing on glacial sedimentology.