Zoom: From Atoms and Galaxies to Blizzards and Bees: How Everything Moves by Bob Berman Page B

pathetically. Inside, floors slant so dramatically that one can almost slide from the bedrooms at either end toward the kitchen in the middle. On this trip, one dispirited native lamented the astronomical costs he was facing, first to jack up the entire building and then to try to create flowing air beneath it so that the frost can reestablish itself and remain year-round. The problem is unpredictability. The ideal technique—building on stilts so that cold air ventilates beneath—usually preserves the permafrost and keeps the house level.
    Throughout this vast state in summer, the top few feet of permafrost melts, but the water has nowhere to flow. This creates billions of stagnant pools of various sizes that are perfect mosquito breeding grounds. It’s a nightmare. Slap your arm on any random spot between May and August and you will kill ten mosquitoes.
    The slow-motion drama of heaving and settling ice and the homes built on them plays out all across Earth’s frozen wastelands. Meanwhile the weight of countless snowfalls typically compacts everything below them into ice. In places, this cobalt-blue ice remains rock-hard for tens of thousands of years. We know this from analyzing bubbles of trapped air, which reveal the contents of our atmosphere as it was long before humans made fire or untold domesticated cattle belched methane.
    Meteorites plow into the snow, become entrapped, and emerge only when that ice layer has completed its mysterious slow journey down, sideways, and eventually back up to the surface. In the vast parts of Antarctica, where ordinary terrestrial rocks have no business lying on the snowfields, researchers in snowmobiles enjoy gathering up any solitary stones they find, knowing they’ve probably just snagged a valuable visitor from space using this no-brainer method. The famous black Antarctic meteorite ALH84001, which originally came from Mars, lay conspicuously on the snowy surface of the Allan Hills region when a snowmobiler found it in 1984. It had resurfaced sixteen thousand years after its impact and initial burial, having been subjected to remorseless icy, hydrolic cycles of pressures, releases, and movements in various directions unchronicled and unknowable by anyone.
    Slow motion is ice’s solemn oath. Even its beginnings are leisurely, since snow typically falls at three miles an hour—the same speed a person walks. But if the snow compresses over a glacial field, it naturally partakes of that ice sheet’s even slower creep to the sea. These flowing ice rivers move anywhere from ten feet to one hundred feet a day, depending mostly on the slope of the land. Typical glaciers move a foot an hour, just barely too slow to notice.
    Yet beneath much of Alaska’s immobile snowy landscape is lively movement. It’s an entire biological world. This is the subnivean realm.
    You don’t need to be in Alaska to experience the subnivean universe or even to fall in love with the word. In most of the United States and Europe, the winter landscape—so seemingly motionless—hides constant animated activity on the part of small mammals, including voles, mice, and lemmings. They not only adapt to the snow cover but also rely on it for their very survival. They scurry along wide corridors an inch or two high in the gap between the ground and the bottom of the snowpack, a gap formed after the snowpack contracts a bit.
    This region, illuminated diffusely from above in seemingly perpetual twilight, enjoys an air temperature around the freezing point once the snow cover is more than a half foot thick, thus creating insulation against the frigid air above. This subnivean system of open spaces and tunnels lets these mammals move unseen by many predators, although foxes and owls can hear the scurrying and usually know exactly where to pounce.
    Everything seems motionless in this winter scene. Yet under the snow, in a gap between its lower boundary and the ground, lurks the subnivean realm, where small mammals