Detailed surficial geologic mapping and terrain analysis of the Blue Hills Felsenmeer Valley, Rusk County, Wisconsin

Abstract

The Barron Quartzite of west-central Wisconsin forms a rolling upland known locally as the Blue Hills. Our study concerns the Blue Hills Felsenmeer State Natural Area in Rusk County, which encompasses a small valley 300 meters long, 100 meters wide, with 25 meters of relief. Underlain by angular quartzite boulders averaging 30 cm. long, the valley contains little to no vegetation and contrasts markedly with the surrounding mixed conifer and hardwood forests. This work is part of a larger study re-examining the origin of this valley in an effort to evaluate if the feature is truly a felsenmeer (rocks frost-shatteed in place), and determine if other mechanisms, such as talus accumulation, may account for this feature (Thompson and Syverson, 2006). Our mapping and interpretations use a LiDAR (Light Detection and Ranging) base with a two-foot contour interval provided by courtesy of the Barron County Soil and Water Conservation Office. LiDAR data were emplyed to generate digital elevation models, which can be used to create shaded-relief maps and conduct terrain analysis. Parameters obtained from digital terrain analysis may provide additional insight regarding the mechanism of landscape development by comparing locations of boulder accumulation with slope angle and aspect values using GIS.