Throughout the surrounding hills, the remains of hundreds of charcoal pits survive. Workers called colliers tended these pits to transform wood into charcoal, a pure carbon fuel. They ignited stacked wood covered with leaves and dirt to begin the process, and it took ten days to two weeks for the wood to come to foot, or char completely. Around the clock, colliers watched the smoldering pits carefully to prevent open flame from igniting and ruining the charcoal. The best charcoal here was made by gradually charring chestnut, oak, and hickory wood. Master colliers and their helpers made charcoal during spring, summer, and fall. Seldom seen here, they lived as nomads in primitive, cone-shaped huts. By centralizing their homesites, two or three charcoal workers could tend up to nine charcoal pits at a time.