John Ackerman, the largest private cave owner in Minnesota, has been called a kook and accused of land-snatching, but supporters say he is nothing short of a protector of subterranean wilderness. Source: Cave Collector in Minnesota Hunts for Additions to His Empire ; ;Related ArticlesCanadian Documents Suggest Shift on PipelineWhere Sand Is Gold, the Reserves Are Running DryTexas Tribune: Making Some Effort, but North Texas Continues to Run the Water ;

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Cave Collector in Minnesota Hunts for Additions to His Empire