Arctic Alaska’s mysterious stone walls HIKING ACROSS THE ARCTIC TUNDRA ONE RECENT YEAR, I happened upon an unusual array of rocks, unlike anything I’d seen in more than three decades of exploring Alaska’s diverse wildlands. Upon discovering the piled stones, two thoughts ashed through my mind. Who would build rock walls deep in the Brooks Range wilderness, many miles from any settlement? And why? I knew that during their nomadic days, the region’s Nunamiut Eskimos had in places built “stone guards,” called inuksuk, along caribou migration routes. Intended to mimic humans, the stone gures helped the Nunamiut steer caribou toward areas where the animals could be more easily harvested. But these rocky forms were totally different. Built along one edge of a wide valley bottom in the central Brooks Range, they had been shaped into walls, not widely spaced cairns. And those walls were far too low—from a few inches…