331Fc Pierre Shale Plains

Landscape Characteristics:

Rolling plains and low hills, floodplains, fans, and terraces that formed in alluvium and colluvium weathered from shale and sandstone. Badlands and river breaks occur along the lower Yellowstone and Powder rivers. Elevations range from 1000 to 3500 feet. Drainage density is moderate.

Climate:

Mean annual precipitation ranges from 10 to 14 inches, about 20 percent falling as snow. The soil temperature and moisture regimes are frigid and aridic ustic. Summers are usually dry.

Potential Vegetation:

Wheatgrass-needlegrass and Grama-needlegrass-wheatgrass

Relationships of Dominant Map Unit Components:

Landform Geology Soil Taxa
Plains/hills Shale/sandstone Torriorthents/Ustorthents/Camborthids/Ustochrepts
Terraces Alluvium Haplargids/Haploborolls/Torrifluvents/Camborthids
Fans/floodplains Alluvium Camborthids/Torrifluvents
River breaks Alluvium/colluvium Torriorthents

Disturbance and Land Use:

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