This report has to do with the physical geography of the area in south central Wisconsin, shown on the accompanying sketch map, Plate I . The region is of especial interest, both because of its striking scenery, and because it illustrates clearly many of the principles involved in the evolution of the geography of land surfaces. Generally speaking, the region is an undulating plain, above which rise a few notable elevations, chief among which are the Baraboo quartzite ranges, marked by diagonal

From loose sand to quartzite. —To understand the geography of a region it is necessary to understand the nature of the materials, the sculpture of which has made the geography. It has already been indicated (p. 14 ) that the Huronian quartzite of which the most prominent elevations of this region are composed, was once loose sand. Even at the risk of repetition, the steps in its history are here recounted. The source of the sand was probably the still older rocks of the land in the northern part

Elements of erosion. —The general process of subaerial erosion is divisible into the several sub-processes of weathering, transportation, and corrasion. [5] Weathering is the term applied to all those processes which disintegrate and disrupt exposed surfaces of rock. It is accomplished chiefly by solution, changes in temperature, the wedge-work of ice and roots, the borings of animals, and such chemical changes as surface water and air effect. The products of weathering are transported by the di

The uplift following the period of Paleozoic deposition in south central Wisconsin, inaugurated a period of erosion which, with some interruptions, has continued to the present day. The processes of weathering began as soon as the surface was exposed to the weather, and corrasion by running water began with the first shower which fell upon it. The sediment worn from the land was carried back to the sea, there to be used in the building of still younger formations. The rate of erosion of a land s

The eastern part of the area with which this report deals, is covered with a mantle of drift which, as already pointed out, has greatly modified the details of its topography. To the consideration of the drift and its history attention is now turned. The drift. —The drift consists of a body of clay, sand, gravel and bowlders, spread out as a cover of unequal thickness over the rock formations beneath. These various classes of material may be confusedly commingled, or they may be more or less dis