Regional Landscape Ecosystems of Michigan, Minnesota, and Wisconsin
SUB-SUBSECTION VII.6.1. Onaway
DISCUSSION: Ground moraine, supporting localized drumlin fields, occupies the eastern three-quarters of the sub-subsection. The western quarter contains several large lakes and sandy lake plain interspersed with small areas of ground moraine.
ELEVATION: 595 to 1,100 feet (181 to 335 m).
AREA: 1,931 square miles (5,005 sq km).
STATES: Michigan.
CLIMATE: Growing season ranges from approximately 100 days at the inland edge in the south to 130 days in the north along Lake Huron (Eichenlaub et al. 1990). Extreme minimum temperature ranges from approximately -46½F inland to -34½F closer to Lake Huron. Average annual precipitation is 30 to 32 inches. Annual snowfall is 140 inches in the west near Lake Michigan and only 70 inches at the eastern edge of the sub-subsection.
BEDROCK GEOLOGY: Glacial drift is as thick as 500 feet at the inland margin of the sub-subsection and is discontinuous within 30 miles of the shorelines of Lake Michigan and Lake Huron (Akers 1938, Haag 1976). The underlying bedrock consists of Mississippian and Devonian marine and near-shore sedimentary deposits (Milstein 1987, Dorr and Eschman 1984). Limestone, dolomite, and gypsum are locally exposed and mined. Devonian bedrock in the sub-subsection is a source for salt, brine, and major petroleum reservoirs (Dorr and Eschman 1984).
LANDFORMS: Rolling to moderately sloping groundmoraine topography. Drumlins are common on the ground moraine of the eastern threequarters. Readvancing glaciers sculpted the southeastwardtrending drumlin fields. Most of the drumlins are less than 60 feet high, one-eighth to one-fourth mile wide, and about 1 mile long. Individual drumlins are typically separated by poorly drained outwash. The western quarter contains several large lakes and large areas of lake plain interspersed with small ground moraine deposits. The lacustrine deposits are from early Algonquin time, when the small groundmoraine deposits remained as "islands" above the level of Glacial Lake Algonquin (Burgis and Eschman 1981, Dorr and Eschman 1984).
Elevations are generally lower to the northeast near Lake Huron and higher to the southwest along the boundary with the Vanderbilt sub-subsection (VII.2.3). Small areas of exposed limestone bedrock are common in the ground moraine, and karst topography is also present. The ground moraine is broken by a broad outwash channel west of the town of Hawks.
LAKES AND STREAMS: Several large lakes are located here, including Burt, Douglas, Mullett, and Black Lakes. Major rivers are the Maple, Sturgeon, Black, Cheboygan, and Pigeon.
SOILS: The rolling hills and drumlins of the eastern section of ground moraine, characterized by slopes in the 0 to 12 percent slope class, have highly variable drainage and soil texture. Gravelly sandy loams are common. The gravel and angular rock fragments are predominantly limestone, derived from bedrock at the northern edge of the drumlin fields (Burgis and Eschman 1981). The glacial deposits within the drumlin fields are primarily brown, sandy tills, but these are overlain locally by red, sandy till or lacustrine deposits. Moderately well to well drained sands and sandy loams typify the drumlins. The depressions between the drumlins are generally poorly drained and constitute more of the landscape than the drumlin ridges.
Soils of the outwash channels vary from sand to gravel, and drainage conditions vary from excessively well drained to very poorly drained. The outwash contains several kettle lakes.
PRESETTLEMENT VEGETATION: Most of the drumlins supported northern hardwood forest, dominated by sugar maple, beech, basswood, hophornbeam, white ash, and hemlock (Comer et al. 1993a). In the southeast and near Black Lake, some sandy drumlins surrounded by droughty outwash supported red pine forest, with red oak and bigtooth aspen. Some of the smaller, low drumlin ridges were dominated by hemlock or a mix of hemlock and white pine; similar to vegetation found on the smaller drumlins in Menominee County (Sub-subsection VIII.3.1).
The poorly drained outwash and ground moraine surrounding the drumlins typically supported forested wetlands of northern white-cedar. Cedar was commonly the dominant at the upland margins of wetlands, but increasing amounts of tamarack and black spruce occurred in the center of the wetlands. Other species observed in these forested wetlands included trembling aspen, balsam poplar, paper birch, black ash, white pine, hemlock, willow, and speckled alder.
NATURAL DISTURBANCE: Windthrows were noted along the boundary with the Cheboygan sub-subsection (VII.6.3), but most of these windthrows occurred on that lake plain, not on the moraines of this sub-subsection.
PRESENT VEGETATION AND LAND USE: Most of this sub-subsection remains forested and is either part of State forest or commercial forest lands. Most of the drumlin ridges were cleared for agriculture, primarily for pasture, but also for some row crops and potatoes. The soils are very rocky; the rocks removed from fields form huge mounds on the landscape, and many have been built into fieldstone houses. Some of the wetlands have also been drained for pasture, but most remain intact.
RARE PLANT COMMUNITIES: None identified to date.
RARE PLANTS: Armoracia aquatica (lake cress), Carex nigra (black sedge), Cirsium pitcheri (Pitcher's thistle), Iris lacustris (dwarf lake iris), Juncus militaris (bayonet rush), Mimulus glabratus var. michiganensis (Michigan monkey-flower), Tanacetum huronense (Lake Huron tansy).
RARE ANIMALS: Brychius hungerfordi (Hungerford's crawling water beetle), Buteo lineatus (red-shouldered hawk), Charadrius melodus (piping plover), Lanius ludovicians (loggerhead shrike).
NATURAL AREAS: Little Traverse Conservancy Preserves: Swift, Raunecker, W. Wequetonsing, Bartley, Schachinger, Bissell, James, Fischer, Sandford, Meadowgate, Fairbairn, Morley, Burley, Fisk, Goldman, Rockwell, Menonaqua Woods, Round Lake, L'Arbre Croche, Rocky Point, Orchis Fen, McCune, Bryan; Other: Colonial Point Forest Preserve (University of Michigan Biological Station).
PUBLIC LAND MANAGERS: State Forests: Mackinaw; State Parks: Harrisville, Negwegon, Onaway; National Forests: Huron; Other: University of Michigan Biological Station.
CONSERVATION CONCERNS: Partially because of insufficient biological surveys, little natural area protection has been achieved for this inland sub-subsection.
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