METEORITES AND BLUE ICE

The well known rock cycle describes the ways in which natural processes degrade and disperse geological materials, sorting their components and converting them into the raw materials of new, and often very different, rocks. At the earth's surface, meteorites are further from chemical equilibrium than most terrestrial rocks and therefore are more susceptible to destruction by weathering and dispersal of their components. They are also very rare among the overwhelming background of terrestrial materials. This is not true of the meteorites we find in Antarctica – they resist weathering for long periods of time and are often found in high concentrations on exposed patches of bluish ice at, or above, about 2000 m elevation. If a patch of blue ice contains a concentration of meteorites we call it a meteorite stranding surface. To a meteoriticist, the levels of concentration are almost unbelievable: as of December, 1999, Japanese, US and European field teams had searched only about 3500 km2 of blue ice and recovered around 17 800 meteorite specimens.

Until recently, much emphasis had been put on the “treasure trove” aspect of the meteorite finds and their demonstrated value as scientific specimens, while very little attention had been given to the “treasure chests,” i.e., the sites where they are found. These sites and the meteorites found on them are linked to the history of the ice sheet and to climate change.