Maybe you’ve been awed by the great walls of stone exposed by road cuts. But it’s the soil skimming the top, like icing on a cake, that should impress you. Compared with the grasslands and forests, that skinny layer doesn’t look like much. But the soil truly is the frosting on the Earth.Soil sustains us. Without it, we’d have no air to breathe, no pure water to drink, no food to eat. We’d drown in our own wastes. “One handful of soil contains billions of organisms that—at this very moment—are eating something living or dead, or recycling something so we can eat, breathe, or have clothes to wear,” says soil scientist Kate Butler.