feet at the southwest end of the study area and reaching nearly 

 8,800 feet on the crest of the Pryors. Wetlands and riparian 

 areas are very limited in the study area, and we made no attempt 

 to sample these rare but important communities. We did not 

 conduct surveys on Bighorn Canyon N.R.A. or on private lands 

 within the study area. 



The oldest formation outcropping in the study area is the 

 Madison limestone v/hich forms the south slopes of the Pryor 

 Mountains. On more level terrain south of the mountain slopes, 

 younger formations overlie the Madison limestone. These are 

 Paleozoic and late Mesozoic sediments, predominantly sandstones 

 and shales. The red sandstones and siltstones interbedded with 

 thin lenses of gypsum of the Chugwater formation are particularly 

 conspicuous (Richards 1955) . A geologic history of the area is 

 provided by Knight et al. (1987) . 



Soils of the study area are predominantly Entisols, 

 Mollisols, and Aridisols (Kratz 1988). In general, soils in the 

 northeast portion of the Pryor Mountains Desert are sandy or 

 silty and often calcareous, v/hile those in the south and v;est 

 portions have a higher clay content and are often saline. Very 

 sandy soils occur locally where they v/eather from sandstone 

 outcrops. Productivity of the vegetation is lov; due to the arid 

 climate. As a result, soil development is minimal and organic 

 matter is low. Shallov; soils formed over Chugwater sandstone are 

 particularly barren. The soils of forests, woodlands, and 

 subalpine grasslands in the study area are mostly derived from 

 calcareous parent materials and vary from sandy loams to loams 

 and from clay loams to clays. 



Climate in the lower portion of the study area is semi-arid. 

 Bridger, Montana, 10 miles north of the west end of the study 

 area at 3,680 feet, receives an average of 12.7 inches of 

 precipitation annually, and mean daily temperatures for January 

 and July are 21.5°F and 70,5°F respectively (NOAA 1982). Lovell, 

 Wyoming, 10 miles south of the east end of the study area at 

 3,800 feet, receives an average of 7.1 inches of precipitation 

 annually. Daily temperatures averaged 16.8° F in January and 

 71.8°F in July (Knight et al. 1987). Spring and early summer 

 rainfall accounts for two-thirds of the annual precipitation, the 

 balance coming as snow (Knight et al. 1987). The Pryor Mountains 

 are undoubtedly cooler and moister. Mean annual precipitation on 

 the crest of the Pryor Mountains is estimated to be 20 inches 

 (USDA-SCS 1981) . 



