Area where the Arikaree aquifer is absent, Pine Ridge Indian Reservation and Bennett County, South Dakota
This data set describes the area within the Pine Ridge Indian Reservation where the Arikaree aquifer 
(Arikaree Formation) is absent. This absent area includes areas where the Arikaree Formation has 
been eroded and where outcrops of geologic units older than the Arikaree Formation are present at 
the land surface.