WALK INTO A PATCH OF forest in New England, and chances are you will—almost literally—stumble across a stone wall.... estimates [are] that there are more than 100,000 miles of old, disused stone walls out there, or enough to circle the globe four times.Who would build a stone wall, let alone hundreds of thousands of miles of them, in the middle of the forest? No one.
Rather, they were built around farms that have fallen back into forest.
The supply of stone seemed endless. A field would be cleared in the autumn, and there would be a whole new crop of stones in the spring. This is due to a process known as “frost heave.” As deforested soils freeze and thaw, stones shift and migrate to the surface. “People in the Northeast thought that the devil had put them there,” says Susan Allport, author of the book Sermons in Stone: The Stone Walls of New England and New York. “They just kept coming.”
This is also true here. There are a lot of rock walls on the mountain, where once there were cattle pastures. Now there is forest again, with a few groves of old apple trees marking where once someone's home stood.
Though the population continues to climb, we are over a demographic cliff in much of the world as birth rates drop below replacement levels. China, for example, is likely to have fewer people than the United States by the end of the century. It will be interesting, for those who come after, to wander in the renewed wilderness where once were farms -- neighborhoods -- cities.




