Periglacial Features in the Driftless Area of Southern Wisconsin

Abstract

At several places in the Driftless Area there occur anomalous surface features not readily explicable on the basis of processes now active. In the Baraboo area, blocks of quartzite from the pre-Cambrian bedrock have accumulated in block streams, block fields, rubble zones, and talus, on slopes ranging from 50 to 360. Locally, small valleys have been choked by the rubble. In the Blue Mound area, block streams, block fields, and isolated rock masses, derived from the Niagara chert which caps the mound, are found at distances of up to nearly 1 mile from the parent ledges and on slopes down to slightly less than 40. At both places the block accumulations are either surrounded or partially overgrown by vegetation and show the effects of long-continued weathering. Nowhere is there any indication of appreciable movement at the present time. The features in question are fossil forms, now in a state of stagnation and decay. They are best explained as products of periglacial frost weathering, solifluction, and ...