Guardian: The National Park Service is beginning to excavate the mouth of an unexplored cave in the Black Hills of South Dakota, and researchers believe it could help broaden our understanding of how the regions climate has changed over thousands of years.
A park service worker found Persistence Cave in 2004 on the grounds of Wind Cave national park, in western South Dakota, but the agency kept it quiet, partly to prevent amateur spelunkers from trying to explore the well-preserved site.
On Monday,...