Four furnaces dating to this period have been excavated. The furnaces are estimated
to have been 3m high from tap channel to furnace top, and water-powered. The furnaces
produced cast iron.
The landscape model proposed is that a furnace operated intensely for a few months
in a year The following year the smelters built a new furnace at another location.
Thus the furnace site migrated around the valley returning to the first site perhaps
some 10-15 years later by which time the local woodland would have regenerated to
produce the charcoal for the smelt.