Is there an untrodden foot of ground left? That's Paul Bogard's mission in THE GROUND BENEATH US, and early on his quest he realizes something astounding: when we step outside and look down, most of us in the industrialized world see an unnatural surface, likely some version of asphalt or concrete. In fact, we have some 61,000 square miles of paved ground in the United States, an amount that together would be larger than any state east of the Mississippi. Increasingly we live separated from the natural ground itself, concealing from us our profound relationship to the source not only of our food, water, and energy, but to