These pillars—located outside a rest area off Highway 80 in Adair County, Iowa—represent the topsoil Iowa has lost since large-scale farming began 150 years ago. In the 19th century, Iowa had 14-16 inches of topsoil. Today, it has just 6-8 inches of the stuff, and more is being lost all the time. The irony: The very farms that are depleting the topsoil desperately need it, too. (Image: RDG)
Maggie Koerth-Baker is the science editor at BoingBoing.net. She writes a monthly column for The New York Times Magazine and is the author of Before the Lights Go Out, a book about electricity, infrastructure, and the future of energy. You can find Maggie on Twitter and Facebook.