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SUB-SUBSECTIONS: Black Duck Till Plain (X.6.1), Bemidji and Bagley Outwash Plains (X.6.2). (See figure 3.)

ELEVATION: 1,200 to 1,610 feet (366 to 491 m).

AREA: 3,176 square miles (8,232 sq km).

STATES: Minnesota.

CLIMATE: Average annual precipitation ranges from 22 to 25 inches (University of Minnesota et al. 1980a). Annual snowfall is 44 to 56 inches, highest in the east (Wendland et al. 1992). Growing season ranges from 110 to 120 days. The longest growing season is near Lower Red Lake in the north and Leach Lake in the south; these lakes extend the growing season approximately 10 days. Extreme minimum temperatures are -45½F or colder (Reinke et al. 1993).

BEDROCK: Glacial drift thickness over bedrock is generally between 200 and 500 feet. However, at the extreme northeastern edge of the subsection, drift thickness is 100 feet or less (Olsen and Mossler 1982). The bedrock beneath the subsection is early Precambrian (middle to late Archean) and middle Precambrian (early Proterozoic) gneiss, amphibolite, undifferentiated granite, and metamorphosed mafic to intermediate volcanic and sedimentary rocks, iron formation, metasedi-ments, quartzose sedimentary rocks, slate, metagraywacke, and quartzite.

LANDFORM: The primary landforms are flat, water-reworked till plain, ground moraine, and stagnation moraine, with a broad band of outwash along the southern margin of the subsection. Glacial Lake Aitkin forms the eastern edge. Subsection X.6 forms the headwaters of the Mississippi River.

LAKES AND STREAMS: Large lakes include Cass and Bemidji Lakes, and Lake Winnibigoshish. Kettle lakes are common on both stagnation moraine and pitted outwash.

SOILS: Soils of the moraines are clay and silt loams (University of Minnesota et al. 1969, 1980a). Soils of the outwash plains are primarily excessively or well drained sands, but there are also numerous wetlands with very poorly drained soils. More than 10 percent of the soils are peats.

Soils are classified as Psamments and Aquents on the outwash plains (Anderson and Grigal 1984). Boralfs are the predominant soils on the moraines. Fine-textured soils, ranging from loams to silty clays, characterize the subsection. Approximately 70 to 85 percent of the soils are well drained, depending on the landform (University of Minnesota et al. 1980a). The predominant soils are Boralfs (Anderson and Grigal 1984).

PRESETTLEMENT FOREST: Mixed hardwood and pine forests, dominated by a diverse mix of northern hardwoods and white pine, were found in the most fire-protected areas at the northern edge of the subsection (Marschner 1974). The original vegetation on the more steep and irregular stagnation moraines was largely white pine-red pine forest. The ground moraine supported both aspen-birch and hardwood-pine forests. Jack pine and northern pin oak dominated the droughty outwash plains. Bogs and swamp conifers occupied poorly drained outwash.

NATURAL DISTURBANCE: Fire was probably an important disturbance factor within the white pine-red pine forests, but it is not clear whether the fires were from the Bemidji outwash plain immediately to the south or from lightning fires originating within the pine stands themselves.

PRESENT VEGETATION AND LAND USE: High-quality examples of the following plant communities are well represented in this subsection: northern hardwood forest, red pine forest, black spruce swamp, tamarack swamp, and northern white-cedar swamp.

RARE PLANT COMMUNITIES: None identified to date.

RARE PLANTS: Botrychium mormo (goblin fern), largest concentration in the three States.

RARE ANIMALS: Haliaeetus leucocephalus (bald eagle).

NATURAL AREAS: State Natural Areas: Pennington Bog; Research Natural Areas: Battle Point, Stony Point.

PUBLIC LAND MANAGERS: State Forests: Battleground, Big Fork, Blackduck, Bowstring, Buena Vista, Mississippi Headwaters, Pine Island; State Parks: Lake Bemidji; Wildlife Management Areas: Carmen Borgerding, Mud-goose, Sugar Lake; National Forests: Chippewa, Superior; Other: Three Island Lake County Park.

CONSERVATION CONCERNS: Accelerated timber harvest with resulting fragmentation, loss of mature and old-growth forests, and simplification of forest communities.