Tuesday, August 5, 2008
Inuit snow houses
The Inuit—“the real people”—of Alaska, Arctic-Canada, northeastern Siberia, and Greenland sometimes build shelters out of water, or at least water in one of its solid states, snow. The highly sophisticated design and construction of that kind of igloo (the Inuit word for house) is a major architectural achievement, employing a technology that turns a challenging resource to creating a not merely adequate but ideal house form.
The oldest identifiable lnuit date from about 2000 b.c. Some of them followed immense migratory herds of bison, caribou, and musk ox across the Bering Strait into North America. Since two-month summers made agriculture impossible in their harsh, treeless environment, the Inuit relied for their food on hunting and fishing. Although some Inuit have now become westernized and eat supermarket food, fish and sea mammals remain the mainstay of the traditional diet of many, and groups still follow a seasonal nomadic cycle through their lands. In comparison with other hunter-gatherer cultures, the Inuit have highly developed technologies, craftsmanship, and art. The dogsled is used for long-distance transportation of large loads, and the maneuverable kayak (sealskin-covered canoe) has long been a model for Western societies. Inuit weapons are fashioned from ivory, bone, stone, or sometimes copper and often decorated with elaborate carving. Their clothing—parka, trousers, mittens, boots, and snow goggles—is often made of caribou skins.
It should not be thought (as the stereotype has it) that all Inuit live in snow houses. They have three traditional dwelling types. A summer house is essentially a caribou-, walrus-, or sealskin tent. A winter house is partially excavated and usually built of stone, with a whalebone or driftwood frame supporting a moss or sod covering. Then there is the circular dome-shaped snow house that some groups use as a winter dwelling. But it is more commonly used by hunters as a temporary shelter while traveling on long journeys.
The igloo is built with carefully shaped blocks of snow about 4 feet long, 2 feet high, and 6 to 8 inches thick (about 1.3 by 0.65 by 0.15 meters), weighing about 45 pounds (20 kilograms). The house can be up to 18 feet (5.5 meters) in diameter, with ample headroom for the occupants. Snow texture and consistency is critical, and the suitable hard-packed snow is usually found on a north-facing slope. Tiny pockets of air trapped between the crystals provide a remarkably effective means of thermal insulation. For maximum structural strength, the first row of blocks is set out in a circle. The blocks are shaped to form a kind of ramp beginning at the front of the igloo, as the base of a self-supporting continuous spiral. As the walls rise to merge into the roof, successive tiers of blocks tilt more and overhang more as they rise, until they converge to form the dome, which is closed with a large fitted cap-block. This method allows the builder to work alone if necessary. The cracks between the blocks are packed with soft snow. Once the first two circuits are completed, it is possible to construct an igloo even during a blizzard, because the structure acts as a windbreak. When intended to be occupied for a long time, the igloo has another low wall of snow blocks placed around it, and the space between the two walls is filled with loose snow, improving thermal insulation.
The entrance is a narrow passage, high enough to admit a crawling person and curved to stop the penetration of cold winds. Additional storage vaults may also form part of the house. The translucent snow provides a little light inside the igloo, and sometimes an ice window is employed. A small ventilation hole is cut in the dome. The floors in larger, long-occupancy igloos are often concave, so that cold air falls into a pool. The remainder of the floor surface is covered with furs, while others hung on pegs trap an air layer against the walls, providing interior warmth without melting the snow. The heat generated by the occupants’ bodies and by lamps or camping stoves raises inside temperatures enough to allow the Inuit to move about naked in their houses of snow.