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331Gc Powder River Basin/Breaks/Scoria Hills

Landscape Characteristics:

Dissected plains and hills, terraces, and fans with some river breaks and badlands that formed in alluvium and colluvium from sandstone, shale, and siltstone. Elevations range from 2100 to 4980 feet. Drainage density is moderate to high.

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 dry.

Potential Vegetation:

Grama-needlegrass-wheatgrass with some Eastern ponderosa forest along river breaks and higher elevations.

Relationships of Dominant Map Unit Components:

Landform Geology Soil Taxa
Plains/hills Sedimentary Ustorthents/Argiborolls/Torriorthents/Camborthids
Terraces/fans Alluvium Haplargids/Haploborolls/Torrifluvents
Breaks/badlands Alluvium/colluvium Torriorthents

Disturbance and Land Use:

The primary natural disturbance is drought and erosion. Land use is predominantly livestock grazing.