Sediment properties and origin of Lake Michigan Ice Lobe till

• Main Authors: Albert, Zach, Frievalt, Kurt
• Format: Text
• Language: unknown
• Published: UWM Digital Commons 2015
• Subjects: Life Sciences; Ice Sheet
• Online Access: https://dc.uwm.edu/uwsurca/2015/Poster1/84

The sediment deposited at the end of a retreating ice sheet records both the processes at the time of deposition and links these processes to those of original erosion and sediment transport. These records can be found along the length of recessional moraines through changes in deposited sediments. The sediment of the deposited material provides accessible and easily identifiable samples to tie the source, its transport path, and the final sink together. / As the Lake Michigan lobe of the Laurentide Ice Sheet retreated from its Wisconsin maximum, it deposited multiple moraines, including the Lake Border Morainic sequence in southeastern Wisconsin and northeastern Illinois. In Wisconsin, the largest and latest moraine of this sequence is commonly referred to as the Petrifying Springs Moraine. This moraine is primarily composed of the Oak Creek Formation. Like many of the Laurentide Ice Sheet tills, the sediment in the Oak Creek Formation reflects not only local bedrock sources but also those more distal. / Focusing on the Petrifying Springs moraine in Kenosha County, Wisconsin, initial analysis reveals sedimentologic variation over single boreholes less than two meters deep. Examining the lithology of these samples, we investigate their possible provenance and transport using their lithology and other sedimentologic properties. The grain size data collected betters our understanding of the Lake Border Morainic sequence by allowing for the correlations between sediment depositional processes and ice advances of the Lake Michigan Lobe. The differences in the material properties and grain size show spatial variations in depositional energy and highlight the variability of the processes operating on the edge of a recessional ice sheet.