Sedimentology of the Blue Hills Felsenmeer State Natural Area, Wisconsin Orr 1, I.M., Mohr 1, A.R., Syverson 1, K.M., and Jol 2, H.M. 1 2 Department of Geology and Department of Geography University of Wisconsin, Eau Claire, WI 54702 (E-mail:
[email protected] ) May 15, 2009 Information in this report is modified from a poster presented at the North-Central Geological Society of America meeting in Rockford, IL, on April 3rd , 2009. Official presentation reference: Orr, I.M., Mohr, A.R., Syverson, K.M., and Jol, H.M., 2009, Sedimentology of the Blue Hills Felsenmeer State Natural Area, Wisconsin: Geological Society of America Abstracts with Programs , v. 41, no. 4, p. 63. 1 Abstract (Orr et al., 2009) The Blue Hills Felsenmeer valley in Rusk County, Wisconsin, trends east-west, is 25 m deep, and is 300 m long. The valley walls slope at 25°and are strewn with angular Barron Quartzite boulders. Steep slopes suggest a rock fall (talus) origin for the block field rather than freeze-thaw processes acting in situ (the process of felsenmeer formation). The purpose of this study is to examine the sedimentology of the block field and assess whether it is a felsenmeer or talus deposit. The sedimentology of the Felsenmeer was studied during ten field days. Nine grain-size distributions (n = 306 to 520) were determined by tossing a rope over the blocks and measuring long-axis rock diameters in contact with the rope. Each sample area was mapped using a GPS unit. A ground penetrating radar (GPR) survey was conducted along the long axis of the Felsenmeer valley to discern any internal block-field stratigraphy.