Arguably, the most notable event to define Wisconsin’s geography was the “Wisconsin Glaciation.” It radically altered the geography of North America north of the Ohio River. It consisted of a major advance of the North American Laurentide ice sheet, which covered most of Canada and a large portion of the US.

This Glaciation Episode extended from about 110,000 to 10,000 years ago. It is important to note that this was the most recent glacial period or, said differently, the last glacial period. The Great Lakes resulted from this episode. So did Niagara Falls. It carved the gorge that is now the Upper Mississippi River.

One of the more incredible features of this glaciation was that the ice sheet did not cover the entire state. In layman’s terms, a large hole of geography was never covered by the ice. It is known as the Driftless Area; that is, when it withdrew, the glacier did not leave any drift there because it did not cover this area. This area extended into parts of Minnesota, Iowa, and Illinois. Indeed, in the case of Wisconsin, it left a steep and rugged landscape untouched, something most noticeable when traveling through the southwest region of the state.

The Driftless Area extends into Minnesota, Illinois, and Iowa. It is that part of the American Midwest that was never glaciated. The rugged terrain is due to the lack of glacial deposits or drift. The Area contains deeply-carved river valleys and elevations ranging from 603 to 1,719 feet.

I wish to show you two more maps that will help you understand the state’s geography well.

The scientists have divided the state into five Geographic Provinces, as shown here. If you look carefully, you can see a greenish dotted line outlining the edge of the Driftless area. I have found understanding this map to be most helpful in my travels.

This second map is as helpful as its predecessor, maybe more so. Scientists have defined the Ecological Landscapes of Wisconsin. I drew this from Wisconsin Department of Natural Resources. 2015. The ecological landscapes of Wisconsin: An

assessment of ecological resources and a guide to planning sustainable management.  This document says,

“Ecological Landscapes are 16 areas of Wisconsin with different ecological attributes and management opportunities. They can be used to identify the best areas of the state to manage for different natural communities, key habitats, aquatic features and native plants and animals from an ecosystem management perspective.

“Wisconsin contains a diverse array of ecological features that make it an ecologically important place, continentally and globally. The Tension Zone is an ecoclimatic band that crosses the state from northwest to southeast, separating the prairie-savanna-hardwood forest ecosystems of the south and west from the mixed coniferous-deciduous forest ecosystems of the north and east.”