Source : Webster's Revised Unabridged Dictionary (1913)

Bad lands \Bad" lands"\
   Barren regions, especially in the western United States,
   where horizontal strata (Tertiary deposits) have been often
   eroded into fantastic forms, and much intersected by
   ca[~n]ons, and where lack of wood, water, and forage
   increases the difficulty of traversing the country, whence
   the name, first given by the Canadian French, Mauvaises
   Terres (bad lands).

Source : WordNet®

Bad Lands
     n : an eroded and barren region in southwestern South Dakota and
         northwestern Nebraska [syn: {Badlands}]