THE BIOLOGY OF HARDING COUNTY, NORTHWEST- 

 ERN SOUTH DAKOTA. 

 BY S. S. YISHER. 



INTRODUCTION 



Harding County is located in the northern Great Plains. Be- 

 cause of the variety in topography and soil, many ecological as- 

 sociations are represented. It is believed that a study of the biology 

 of this county will make easier an understanding of the biological 

 conditions of a wide area, and therefore that the following report 

 will have more than local interest. 



Harding county is the most northwestern county in South 

 Dakota. It is bordered on the north by Bowman county, North 

 Dakota, on the west by Custer county, Montana, on the south by 

 Butte county. South Dakota, and on the east by Perkins county. 

 It is approximately 50 miles square and so extends southward 

 nearly to the YVyoming-Montana-South Dakota corner. 



Most of the area is a treeless, semi-arid, rolling plain having 

 an average elevation of about 3,400 feet. Upon this uneven plain 

 rise several large more or less forested buttes (Cave Hills in the 

 north central, Slim Buttes in the east and Short Pine Hills in the 

 southwest), and numerous smaller buttes. Below the general 

 level have been eroded many valleys which are most conspicuous 

 because deepest, towards the borders of the county. Badland areas 

 are scattered widely. The finest examples are at various points 

 in or bordering the buttes, especially at Reva gap in the Slim 

 Buttes and about the northeastern end of the East Short Pine 

 Hills. The "jump off" which extends for several miles eastward 

 from the East Short Pines is notable. 



The drainage is thorough there are no lakes and no stand- 

 ing water except behind small artificial dams and in the shallow 

 water holes (most of which were formed by the blowing away of 

 the soil from small areas) which contain water for short intervals 

 after rains. 



