331Ge Montana Sedimentary Plains

Landscape Characteristics:

Plains and hills formed in residuum and alluvium from shale and sandstone. Some lacustrine sediments also occur. Elevations range from 2100 to 4150 feet. Drainage density is moderate.

Climate:

Mean annual precipitation ranges from 10 to 14 inches, about 30 percent falling as snow. The soil temperature and moisture regimes are frigid and aridic ustic. Summers are dry.

Potential Vegetation:

Grama-needlegrass-wheatgrass with Eastern ponderosa forest on higher elevation hills.

Relationships of Dominant Map Unit Components:

Landform Geology Soil Taxa
Plains/hills Sedimentary Camborthids/Haplargids/Haploborolls/Ustochrepts

Disturbance and Land Use:

The primary natural disturbance is fire and drought. Land use is predominantly livestock grazing with a small amount of dryland farming.