331Dh Montana Glaciated Plains

Landscape Characteristics:

Plains, terraces, fans, and floodplains that formed in glacial till, gravel deposits, and alluvium over clay shale, sandstone, and siltstone. Elevations range from 1800 to 4400 feet. Drainage density is moderate and glacial potholes are common, especially in the northern part of subsection.

Climate:

Mean annual precipitation ranges from 10 to 15 inches, about 20 to 30 percent falling as snow. The soil temperature and moisture regimes are frigid and aridic ustic.

Potential Vegetation:

Grama-needlegrass-wheatgrass

Relationships of Dominant Map Unit Components:

Landform Geology Soil Taxa
Plains Till/shale Argiborolls/Paleargids/Ustorthents/Torriorthents
Terraces/fans/floodplains Gravel deposits/alluvium Torrifluvents/Ustifluvents/Ustochrepts

Disturbance and Land Use:

The primary natural disturbance is drought. Land use is predominantly livestock grazing with some dryland farming.