Some stories are just plain hard to explain, such as this one, from West Virginia:
Charleston Gazette, WV. 5/14/1976
It was discovered July 1, 1975, by Glenn Pierce, the aging caretaker of Oak Grove Cemetery in Morgantown. The sod was pushed up about eight inches, leaving a dark hole on one side. Pierce hesitantly focused the beam of a flashlight inside, then jumped back at the sight of a concrete vault with a broken lid about six feet down.