PrintRunning Out of Trees
The early European settlers in central Pennsylvania (and many other places) wanted iron, turning rusty soils into pig iron in dozens of different furnaces (including Pennsylvania’s Centre Furnace, just down the hill from Penn State’s University Park Campus, where this is being written), and then turning the hunks of iron into useful things in forges (including Pennsylvania’s Valley Forge).
Video: Days of Iron (2:10)
This is a Centre Furnace. The road runs up the hill to Penn State University Park campus and the town of State College. But State College didn't even exist when the university was founded in 1855. The university was built up the hill from the Iron Furnace, and they've been making iron here since 1791.
This is a glass slag. This is what was left when they melted the ore to get the iron out and drained that away and then this chilled and it froze to make the glass. Melting the ore took energy. And the energy came from charcoal, and the charcoal came from trees. To fire a furnace for a year took more than a half a square mile of trees. But the furnace was served by an independent community and it had people in it who built houses and heated them in the winter and cooked, and that took wood too.
Running a furnace and what was around it, took a square mile of trees a year. And there were lots of furnaces and lots of forages, like Valley Forge, that turned the iron into useful things. Furnace closed in 1858. Production moved west to use better ores and to use coal as a fuel because the trees were gone. It was about the same time as peak whale oil, and just before the first modern oil well up the road here in 1859. Today, we have whales and we have trees because we burn fossil algae and fossil trees, oil and coal, and natural gas.
Pennsylvania by itself had dozens of iron furnaces. The early iron furnaces and forges were fueled by charcoal, which was made from trees. As many as 100 workers would spend fall and winter making the charcoal for just one furnace, which used trees from more than half a square mile (more than a square kilometer) per year. Those people were burning a lot of trees in their fireplaces in winter as well, and the forge that converted the pig iron to useful things required as much charcoal as a furnace. Thus, forests and iron-making didn’t coexist for very long—the Commonwealth of Pennsylvania was rapidly converted from “Penn’s Woods” to the “Pennsylvania desert”, with almost no trees or wildlife remaining. You cn see this deforestation in the US in the form of some maps here. And it wasn’t just Pennsylvania, or just Europeans—the growth of the iron industry in China led to deforestation, too, and many other people around the world have cut trees much faster than they grew back.