Dakota County in southeastern Minnesota provides unique exhibits for the study of Pleistocene drifts derived from north and northwest of the Lake Superior region.
No known Nebraskan till was found, but the Kansan is exposed in road cuts in the central and western parts of the county. The surficial geology consists of tills of Illinoian, Early Wisconsin (Iowan), and Late Wisconsin (Cary of both Keewatin and Patrician origins and Mankato) ages and extensive areas of outwash.
The stratigraphic relationships of the once much-disputed Iowan to the Illinoian and the Illinoian to the Kansan are revealed in road cuts in the west.
Post-Iowan tills are restricted to the north and west. The terms “Keewatin” and “Patrician” are retained to indicate the sources of the Cary drifts.