He was penetrating a valley between two spurs flung out from the northern slope of the mountains. Lower down it was chock-ablock with breadloaf-sized rocks that had washed down out of the higher places. The tires of his truck just had to feel their way over those. But beyond a certain point he was driving on smoother terrain that just consisted of exposed bedrock. He passed into the shade of the spur on his right, or west. Sun still shone on the opposite face of the canyon, making the sedimentary layers obvious. One of those layers was white. At first it was high above him, but over the next few miles he gained altitude and rose up to its level. That was where the road ended, in a shady cul-de-sac with a flat floor strewn with rusty old hulks of mining equipment: most notably a rock crusher. The surrounding wall consisted entirely of that white stratum of rock, and the obvious assumption was that it was marble. You could keep driving beyond that point but you’d be driving into the mountain. A hole in the rock face, obviously man-made, served as the mine’s entrance.