Glacial Influence on Dane Waters
Selections of text from the Dane County Multi-Hazard Mitigation Plan (PDF)
Dane County has a varied and unique geologic and physiographic setting. The western part of the county, known as the valley and ridge or “driftless area” is the only part of the county not affected by glaciation. The area is characterized by steep ridges and valleys drained by fast-flowing streams, generally without natural lakes or impoundments.
East of the driftless area is an area of glacial moraines, located at a major drainage divide that is the headwaters of many streams of the Wisconsin, Sugar and Yahara River basins.
East of the moraines in the center of the county is the Yahara River Valley. Here, deep glacial deposits dammed large valleys, forming a chain of large lakes and wetlands. The Yahara River Valley is primarily glacial ground moraine, with extensive areas of peat and marsh deposits. Streams are generally flatter and more sluggish than those in the driftless area. (Read more about the Yahara's geological past on the the UW Water Sustainability and Climate's blog).
The eastern part of the county is known as the drumlin and marsh physiographic area, and consists primarily of general glacial deposits with extensive marshes. This area includes many small drumlin hills interspersed with shallow glacial deposits, which create an extensive system of interconnected wetlands with poorly defined drainage. Small streams wind slowly through the lowlands. The only lakes in this area are small stream impoundments or shallow marshy lakes.
Wisconsin Geological and Natural History Survey
The Wisconsin Geological and Natural History Survey has developed a glacial geological map of Dane County that shows many of the glacial features as well as places of interest. The map can be downloaded from the Wisconsin Geological and Natural History Survey website.