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M332Ej Southwest Montana Intermontane Basins and Valleys

Landscape Characteristics:

Intermontane basins and broad valleys that formed in alluvium, glacial deposits, and Tertiary volcanic materials. Elevations range from 4700 to 7600 feet. Drainage density is low.

Climate:

Mean annual precipitation ranges from 9 to 20 inches, about 10 percent falling as snow. The soil temperature and moisture regimes are frigid and aridic ustic. Parts of the Red Rock Basin and Big Hole Valley have cryic temperature regimes.

Potential Vegetation:

Sagebrush steppe

Relationships of Dominant Map Unit Components:

Landform Geology Soil Taxa
Valley floor Alluvium Haploborolls/Calciorthids/Torriorthents/Cryaquolls
Terraces/foothills Alluvium/till/volcanic deposits Cryoborolls/Cryochrepts

Disturbance and Land Use:

The primary natural disturbances are flooding and fire. Land use is predominantly livestock grazing, agriculture, and urban/suburban development.