Briefs: Permafrost - a glimpse of Alaska's History
In 1963, the Alkirk miner, an experimental tunnelling machine, was tested on the permanently frozen silt, sand and gravel of Hill 456, 10 miles north of Fairbanks, Alaska. The result was a man-made permafrost tunnel that runs 360 feet deep into 40@000 year old frozen soil, the only one of its kind in the Western hemisphere. One-fifth of the Earthfs land area conceals a permafrost layer. Refrigeration units keep the tunnel artificially cooled, especially near the entrance, but despite this, the tunnelfs ice tends to disappear due to sublimation. The tunnel makes it possible to observe various features of permafrost: roots of the remains of Pleistocene plants and of a steppe bison, a species extinct for at least 8000 years, are clearly visible in the tunnel surface. Scientists are working on a fungus that grows at temperatures below freezing. The ice wedges that form in cracks and the other types of ice formation come under special scrutiny: a team of Japanese and American scientists managed to produce live bacteria from a 25@000-year-old ice wedge. Geochemist Tom Douglas claims that the ice can help understand global warming. Douglas envisions a tunnel open to visitors, with a glass casing to protect the walls.