Section M332C Rocky Mountain Front
Geomorphology. There are glaciated mountains with limestone scarps and ridges interspersed with glacial and lacustrine intermontane basins. Alpine ridges and cirques occur at higher elevations. Elevation ranges from 5,500 to 8,500 ft (1,678 to 2,593 m). This Section is within the Northern Rocky Mountains physiographic province.
Lithology and Stratigraphy. Precambrian and Paleozoic limestone and marine clastic rocks occur.
Soil Taxa. Soils include frigid and cryic Ochrepts, Boralfs, Orthents, and Borolls. Fluvents occur in the basin areas. These soils are generally shallow to moderately deep with loamy to sandy textures.
Potential Natural Vegetation. Douglas-fir forest and western spruce-fir forest (15 percent), occur mostly between 4,500 to 8,000 ft (1,360 to 2,425 m). Extensive aspen groves also occur. Limber pine is also present. Foothills prairie (85 percent) occurs on lower elevation foothills. Common grasses include wheatgrasses, fescues, and needlegrass.
Fauna. Birds are typical of the drier, open areas of the northern Rocky Mountains, including such species as common raven, black-capped chickadee, hermit thrush, Cassin's finch, and dark-eyed junco. Other birds include the harlequin duck, blue grouse, spruce grouse, gray jay, black-billed magpie, Clark's nutcracker, American dipper, Townsend's solitaire, American pipit, yellow-rumped warbler, fox sparrow, western tanager, and pine siskin. Several species meet the edge of their range at the intersection of Rocky Mountain and plain, including Vaux's swift. Typical herbivores and carnivores include white-tailed deer, mule deer, elk, moose, black bear, bobcat, and cougar. Smaller common herbivores include the snowshoe hare and the northern flying squirrel. Rare species include the grizzly bear and gray wolf. Herpetofauna typical of this Section are the spotted frog, wood frog, Pacific treefrog, western toad, and long-toed salamander.
Climate. Precipitation ranges from 18 to over 100 in (460 to 2,540 mm), with forests receiving an average of 30 to 40 in (760 to 1,020 mm). Maximum precipitation occurs from spring through early summer; winter precipitation is snow. Severe chinook winds and dramatic fluctuations of winter temperatures are common. Climate is cold continental. Temperature averages 36 to 45 F (2 to 7 C). The growing season averages 45 to 90 days.
Surface Water Characteristics. There is generally a dendritic drainage pattern with some structural control. Major water bodies include St. Mary's lake and Gibson reservoir. Smaller lakes occur in high elevation cirque basins. Major rivers include the Sun and the Middle Fork of the Flathead.
Disturbance Regimes. Fire, insects, and disease are the principal natural sources of disturbance. Strong chinook winds that cause windthrow are also a source of disturbance.
Land Use. Livestock grazing is important, along with some timber harvest. Recreation, watershed, and wildlife habitat are other important land uses.
