Wikipedia
Scowle
Scowles are landscape features which range from amorphous shallow pits to irregular labyrinthine hollows up to several metres deep. and are possibly unique to the Forest of Dean in Gloucestershire, England.
They have traditionally been interpreted as the remains of prehistoric and early historic open-cast iron ore extraction, but investigation undertaken by the Forest of Dean Archaeological Survey from 2003 to 2004 suggests that they have a primarily natural origin which has been exploited by humans.