331Db Montana Isolated Mountain Ranges

Landscape Characteristics:

Mountainsides, foothills, terraces, moraines, and fans that formed in Tertiary volcanics and mixed sedimentary rocks. Continental glaciation influenced these mountain ranges. Elevations range from 2500 to 5500 feet. Drainage density is moderate.

Climate:

Mean annual precipitation ranges from 16 to 30 inches, about 70 percent falling as snow. The soil temperature and moisture regimes are frigid (cryic at higher elevations) and typic ustic. Chinook winds are common.

Potential Vegetation:

Douglas-fir forest at higher elevations with Foothills prairie on foothill and lower elevations.

Relationships of Dominant Map Unit Components:

Landform Geology Soil Taxa
Mountainsides/moraines Till/volcanics/mixed sedimentary Cryoborolls/Cryoboralfs/Cryochrepts
Foothills Volcanics/sedimentary Haploborolls/Paleboralfs
Terraces/fans Mixed sedimentary Argiborolls/Haploborolls

Disturbance and Land Use:

The primary natural disturbance is fire. Land use is predominantly livestock grazing and some timber harvest.