From Forest to Furnace
Hundreds of men labored cutting timber, working the furnace and driving teams of oxen hauling iron ore to the furnace. To fuel the furnaces, the forests were repeatedly cut, and the wood converted to charcoal. Each furnace required cutting 300 to 400 acres of timber annually to keep up with the demand. Charcoal was produced from this timber. The wood was placed onto a pile 30-50 feet in diameter and 25 feet tall. The pile was then covered with a mound of dirt and the timber was burned for 3-30 days, turning the wood into charcoal. These charcoal fires were tended 24 hours a day; so much wood was required for this process that surrounding hillsides were almost completely stripped of their timber.
Courtesy hmdb.org