Haywood, Carl N. (ed.) / Transactions of the Wisconsin Academy of Sciences, Arts and Letters
volume 78 (1990)
Rosen, Carol J.; Day, Michael J.
Glaciated karst terrain in the Door peninsula of Wisconsin, pp. 39-44 PDF (2.3 MB)
Glaciated Karst Terrain in the Door Peninsula of Wisconsin Abstract. Glaciated kanst terrain, which is poorly documented in the United States, is well developed in the Door Peninsula of northeastern Wisconsin. The peninsula is a southeastwarddipping cuesta developed on the Silunian Niagaran dolomite. Wisconsinan glacial plucking east of the escarpment produced glaciokanst features including alternating steps and risers (schichttreppenkarst) and extensive dolomite pavements. Pre- and post-glacial karst landfonms include enlarged crevices (gnikes), sinkholes, and caves. Staircases and pavements are predominantly south- and east-facing and are particularly well developed on the Brussels Hill outlien. Their distribution is as predicted by the general model of northwest-southeast ice movement. Many of the smaller kanst landfonms are postglacial, although shallow features may have an important inherited component, and the larger sinkholes and the caves may antedate Wisconsinan glaciation. Much of the postglacial karst development is in the Burnt Bluff Formation on the western side of the peninsula where the hydraulic gradient is steepest, joints ane dilated, and the drift is thinnest. Regional joint sets at 25, 70, and 155 degrees have strongly influenced cave and sinkhole development. 39 Carol J. Rosen and Michael J. Day Although large areas of carbonate bedrock in the United States experienced the effects of Pleistocene glaciation, glaciokarst—characteristic terrain developed through glaciation of karst landscape—is poorly documented. In many areas glaciokarst is limited because the himestones or dolomites are mantled by thick, often carbonate-rich glacial deposits. These mask any preglacial karst, as well as the effects of glacial erosion, and hinder postglacial karst development. Never- Carol Rosen is an Assistant Professor of Geography at UW-Whitewater. She received her PhD from UWMilwaukee in May, 1990. Her MS Thesis at UWMilwaukee dealt with the Karst geomorphology of the Door Peninsula. Michael Day is an Associate Professor of Geography at UW-Milwaukee. His research focuses on karst geomorphology. He received the DPhil from Oxford University in 1978. theless, glaciokarst is present in some areas, particularly where drift deposits are thin. In this paper we call attention to one major area of glaciated karst terrain developed on dolomites in northeastern Wisconsin and present some initial results of studies of the karst landforms. The Regional Setting The Door Peninsula, which extends some 100 km into Lake Michigan and ranges from 5 to 30 km wide (Fig. 1), is a cuesta developed on the Silurian-aged Niagaran dolomite (Sherrill 1978). The Niagaran Series is approximately 107-m thick and consists dominantly of light gray, medium to coarsegrained, thin-bedded, fossiliferous dolomites. Bioherms are common and are expressed topographically in outliers such as Brussels Hill, the highest point on the peninsula at 260 m (Thwaites and Bertrand 1957).
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