The North American sub-Arctic, home to the indigenous cultures of the far north and the largest region in North America, stretches from Labrador to Alaska and features several ecological zones. Wide swathes of upland and lowland tundra in the coastal areas reflect the former weight of the Laurentide Ice Sheet from the late Pleistocene era. Throughout these sub-Artic tundra areas in both Alaska and Canada, drumlins, glacial moraines, swamps, and post-glacial hummocks provide continuous variation in landforms. In some cases the treeless taiga reaches hundreds of miles longitudinally and latitudinally, into the interior of both Canada and northern and western Alaska. The low-growing sedges, mosses, and lichens provide food and shelter for a plethora of small mammals, indigenous and migratory waterfowl, many species of flies and mosquitoes, and occasional large mammals. The octagonal shapes of post-glacial flora seem flat from...