They took their seats in the plane and set off. Ten minutes later they were crossing the frontier that separated civilization from savagery. Uphill and down, across the deserts of salt or sand, through forests, into the violet depth of canyons, over crag and peak and table-topped mesa, the fence marched on and on, irresistibly the straight line, the geometrical symbol of triumphant human purpose. And at its foot, here and there, a mosaic of white bones, a still unrotted carcase dark on the tawny ground marked the place where deer or steer, puma or porcupine or coyote, or the greedy turkey buzzards drawn down by the whiff of carrion and fulminated as though by a poetic justice, had come too close to the destroying wires.