The Southern Superior Uplands Section (SSU) occurs mainly along the south shore of Lake Superior in northern Wisconsin and has limited extent in Minnesota. The land surface is composed mostly of clayey sediments deposited by Glacial Lake Duluth. The landscape is highly dissected by the Nemadji River and its tributaries and is characterized by steep-sided ravines. The ravine slopes support wet-mesic forests of aspen and paper birch mixed with conifers such as white spruce, balsam fir, white cedar, and white pine; and mesic forests of sugar maple, basswood, and paper birch. High areas between the ravines represent flat, clayey, poorly drained remnants of the glacial lake bed. These sites most commonly have wet forests dominated by black ash mixed with white cedar and yellow birch.
Subsections are units within Sections that are defined using glacial deposition processes, surface bedrock formations, local climate, topographic relief, and the distribution of plants, especially trees. Minnesota has 26 subsections. Printable map of subsections