It happened around 1:30 Saturday afternoon at Baldpate Mountain Park.
Police on the scene told Action News that Robert Goss fell into the hole while searching for artifacts.
His fall caused a boulder to shift and fall on his leg.
Rescue crews were able to free Goss shortly before 5:00 p.m after nearly four hours. He was taken to Capital Health Regional Medical Center in guarded condition for severe leg injuries.
No word what caused the victim to fall.