especially in the southern half of the study area. Salts are derived from 

 the leaching of shale beds in the Tongue River Member of the Fort Union Form- 

 ation and from the Bearpaw Shale. Other formations also have saline shales 

 which may locally contribute to salinity buildup. Leaching of salts may be 

 accelerated where permeable zones have been formed by the burning of coal 

 beds within saline shale sequences. 



Badlands topography is common in areas underlain by the Fox Hills, Hell 

 Creek and Tullock units, primarily in the western third of the area. Silt de- 

 posits, probably wind blown loess (Colliver and Knechtel 1939) mantle many parts 

 of the area and may have influenced the present topography as well as soils. 



Several major kinds of soils are found in the study area. There are 

 Ertisols and Aridisols (Lithosols and Brown soils), e.g. Bainville silt loam, 

 Mollisols (Chestnut and Chernozem soils), e.g. Bearpaw clay loam, Sprole loam, 

 Vida loam; Ertisols and bedrock outcrops (badlands); Aridisols and some 

 agrids and natragrids (glaciated Brown and Solidized-Solentz soils), e.g. 

 Phillips loam, Scobey clay loam, Thoeny loam, and Fluvents (allivial soils) 

 e.g. Bowdoin clay, Lohmiller clay loam (after Southard 1973). 



The study area is primarily a temperate grassland, or more precisely a 

 mixed grass prairie (Weaver and Albertson, 1956). A second major biome type 

 in the area is the Artemisia dominated cool semi-desert of Whittaker (1975). 

 Other less abundant vegetation types occur in atypical sites. 



Several authors have mapped the vegetation of the area at rather small 

 scale, largely using existing data and some new samples or listing of 

 species. 



Kuchler (1964) has indicated that the area is potentially the Bouteloua 

 qracilis - Stipa comata - Agropyron smithii vegetation type. Morris et al. 

 (1964) has mapped the natural vegetation of the western portion of study 

 area as the Agropyron smithii - Stipa comata - Bouteloua gracil is type and 

 the eastern portion as a Stipa comata - Agropyron smithii - Bouteloua 

 gracilis type. Certainly these are the three major species of the area. 



Ross and Hunter (1975) have identified three principal range sites for 

 the area; the silty range site having 10 to 14 inches (25.4 cm - 

 35.6 cm) precipitation; the silty-clayey range site complex having 10 to 

 14 inches (25.4 cm - 35.6 cm) precipitation; and to a lesser extent the 

 badlands. The three major climax dominants for the first two range sites 

 are Agropyron smithii (and A. dasystachum ) , Andropogon scoparius , and 

 Stipa comata . The three principal increasers for these sites are Bouteloua 

 gracilis , Stipa comata , and Carex filifolia . 



Payne (1973) had indicated three major rangeland types for the area. 

 The southern portion of the study area is the Prairie County grassland, 

 dominated by Stipa Comata , Carex filifolia , and Bouteloua gracilis . The 

 northwest portion of the area is the central grassland, characterized by 

 scattered sagebrush ( Artemisia sp . ) , and Bouteloua gracilis , Agropyron 

 smithi i , and Stipa comata . The northeastern part of the study area is the 

 Northeastern grassland, distinguished by Andropogon scoparius and also 

 Bouteloua gracilis , Stipa comata , and Agropyron smithii . 



