For about a hundred years, the main economic activity in the upland parts of the park was making charcoal for the Catoctin furnace. Using the methods of those days, it took 200 bushels of charcoal to make one ton of pig iron. So an active furnace burned through about 500 acres of trees in a year. The owners of the furnace owned thousands of acres of land up here in the mountains, but even that wasn't enough. They still bought a lot of timber from their neighbors as well. The way they made charcoal was they dug out a wide, shallow hole 30, even 50 feet across. They piled up the logs on top of it. Then, they covered it over with dirt leaving just a couple of holes, so that the fire smoldered and charred the wood, rather than consuming it. Those fires burned for 2 to 3 weeks and the whole time they had to be watched to make sure that they never got too hot or went out. The men who watched the fires were called charcoal burners, or colliers. We don't know much about the colliers, but in pictures they're always old men, so they may have been semi-retired loggers or furnace men. They lived up here on the mountain in crazy wood shacks while they tended the fires full time. Once the fired had burned out, they closed up the holes so the fire would die. When it cooled, they wracked the soil off to expose the charcoal, loaded it up in wagons, and took it down the mountain. The archeological record of the charcoal industry consists of two things. The foundation of the huts, which are usually just a little mound of dirt with a pile of stones at one end marking where the hearth or chimney is. Or, the charcoal hearths themselves. These are just wide, shallow depressions, which you can see as you walk through the woods on the mountain. There are hundreds of them up here. The only way to know for sure is to stick a shovel in the ground, turn the soil over, and see how black it is from all the charcoal. There's your black charcoal-stained soil. Charcoal hearths are not much to see, but they're the only remnant of a whole way of life that's disappeared from our part of the world.