Subsection X.12 consists of a flat, poorly drained lake plain. Growing season is short, from 98 to 111 days, and shortest near the eastern edge. At the western edge of the basin, where drift thicknesses are generally greatest, drift is as thick as 300 feet. The peatlands occupy a large glacial lake bed.
Sediments vary considerably in texture across the extensive lake bed.
Sandy beach ridges are exposed throughout the subsection. A greater percentage of organic soils is in the center of the lake basin, with increased amounts of poorly drained mineral soils near the edges. About 75 percent of the soils are peats in this part of the basin. As in the northwest, clays and loams underlie the sands at 2 to 4 feet. See presettlement vegetation.