The Alexandria Moraine Complex forms the western and southern boundary of this subsection. The eastern boundary was delineated based on general landform boundaries and the separation of lands dominated in the past by northern hardwoods from lands dominated by conifer or aspen-birch forest.
Steep slopes, high hills and lakes formed in glacial end moraines and outwash plains characterize this subsection. Presettlement vegetation included maple-basswood forests interspersed with oak savannas, tallgrass prairies, and oak forests. Much of this region is currently farmed. Where lakes are present, tourism is common.
Ice stagnation moraines, end moraines, ground moraines, and outwash plains are major landforms present in this subsection. Kettle lakes are numerous, both on moraine and outwash deposits (Albert 1993). Parent material is primarily calcareous glacial till and outwash sediments. The glacial till is calcareous loamy sediment deposited by the last major glaciation (Wisconsin age).
There are 100 to 500 feet of glacial drift covering most of the bedrock in this subsection. The thickest drift is in the northwestern half (Olsen and Mossler 1982). Middle Precambrian granitic bedrock is locally exposed in the southeast, along the Crow River (Morey 1976, 1981). Bedrock underlying the subsection is diverse. Cretaceous shale, sandstone, and clay and Lower Precambrian granite, meta-sedimentary and metaigneous gneiss, schist, and migmatite underlie the southern half (Morey 1976). To the north are metasedimentary rocks, iron formation, enschist, and metavolcanic rocks (Albert 1993).
Soil textures range from loamy sands and sandy loams on outwash plains to loams and clay loams on moraines. Loamy soils are prevalent. Most are classified as Borolls (cold well drained soils developed under grassland) and Aquolls (wet soils developed under grassland), with some Udolls (dry soils developed under grassland, with soil temperatures warmer than Borolls). There are some Alfisols (soils developed under forested or savanna conditions) (Cummins and Grigal 1981).
Total annual precipitation ranges from 24 inches in the west to 27 inches in the east. Growing season precipitation ranges from 10.5 to 11.5 inches. The growing season ranges from approximately 122 days in the north to 140 days in the south.
The Alexandria Moraine forms a high ridge that is the headwaters region of many rivers and streams flowing east and west. The drainage network is young and undeveloped throughout this subsection. Major rivers include the Chippewa, the Long Prairie, the Sauk, and the Crow Wing rivers. The Mississippi River forms a portion of the east boundary. The Continental Divide splits this subsection. North of the divide, water eventually flows into Hudson Bay. South of the divide, water flows into the Mississippi River system. The subsection has numerous lakes, with over 400 lakes greater than 160 acres in size. The majority of these are present on end moraines and pitted outwash plains.
Irregular topography and presence of numerous lakes and wetlands provided a partial barrier to fire, resulting in woodland or forest rather than prairie vegetation. A mosaic of tallgrass prairie, aspen-oak land, and oak openings or savanna was present along the prairie boundary to the west (Marschner 1974). Mixed forests of oaks, sugar maple, basswood, and other hardwoods were present in fire protected sites farther east. Tallgrass prairie grew on more level terrain within the subsection.
Present vegetation and land use
Agriculture is the major land use. Wetlands and lakes in poorly-drained potholes provide opportunities for recreation or wildlife habitat. Some upland forests remain, adjacent to lakes or on steep landscapes. Tourism is important, especially in areas around lakes.
Fire was important in oak savanna development. Windthrow was common in the sugar maple-basswood forests. Tornados and other high wind events also created natural disturbances (Albert 1993).
Species in Greatest Conservation need for the Hardwood Hills Subsection