Potential meltwater incision of the Blue Hills Felsenmeer Valley, Rusk County, Wisconsin, during the Late Wisconsin Glaciation

Abstract

The Blue Hills Felsenmeer valley contains a high concentration of angular quartzite boulders. The valley has a small modern water-catchment area that heads at an elevation of 1456 ft. based on LiDAR data. Cahow (no date) proposed the valley was cut by Chippewa Lobe meltwater during the late Chippewa Phase of the late Wisconsin Glaciation. The purpose of this study is to determine if the Chippewa Lobe ice surface was sufficiently high to supply meltwater to erode the valley. We mapped the maximum extent of the Chippewa Moraine using domestic well logs, the Rusk County soil survey, and aerial photographs. Field observations verified the ice-margin position marked by chaotic hummocks, kettles, and ice-walled-lake plains. Hummock-crest elevations were measured within 2 km of the former ice-margin position near the felsenmeer valley head. Clark (1992) reports that this provides a minimum ice-surface elevation estimate within 30-100 ft of the actual value. Hummock crest elevations between 1400-1410 ft show that the ice surface was within 56 ft of the valley-head threshold. Thus, meltwater from the late Chippewa Phase of the late Wisconsin Glaciation could have eroded the valley.