We bought a lot of books in Mesa Verde National Park, partly because there’s not much to do after nightfall, and partly because the ruins are so interesting that you feel compelled to learn as much as you can about them. It’s a strange park, Mesa Verde; it’s the only one in the National Park Service that’s organized around ruins rather than natural scenery. At first glance from your “hotel” (translation: motel) room at Farview Lodge there’s just a long expanse down the mesa toward the canyons, and on a clear day you can see Shiprock, 65 miles away. The…