He turned his head, raised his good arm, gestured at the ridge that rose above them to the south: a blade of cream-colored granite, patched with snow, skirted by a ramp of boulders that had been flaking away from it and thundering down into the valley for millions of years. The trail had taken them up onto the ridge’s middle slopes, flying on creosoted stilts over the rubble fields, and terminated at a place where a wall of sound rock jumped out of the talus. The tunnel had been blasted straight into it, aimed horizontally through the heart of the ridge.