Geologist finds permafrost under water

Italian scientists based in Antarctica about 320km northwest of New Zealand's Scott Base have dug up the first sample of underwater permafrost, something not previously thought to exist.

Geologists working out of Italy's Mario Zucchelli research base in Antarctica -- which is serviced from Christchurch -- found permafrost under 3m of water in the Tethys Bay area, the Italian news agency Ansa reported.

Permafrost, or permanently frozen ground, forms when the air temperature is consistently well under the freezing point of water - zero degrees centigrade.

Even though the sea regularly freezes in Antarctica, the ice never reaches the seabed so there is always some water above it. In theory, this should mean that permafrost cannot form.

But one of the 55 scientists and technicians spending the summer at Italy's Ross Sea base, glacier expert Mauro Guglielmin, said ice was found in a 3.2m hole which had been drilled in the seabed to retrieve soil samples.

"The samples appear to contain ice, which shouldn't normally be possible in underwater conditions," he said. The temperature in the ground at that point was -2.5C.

This meant that the permafrost formed thousands of years ago, when the region was colder than it is now, and the land now underwater was dry.

Exactly when it was later covered as global temperatures rose -- melting ice caps and raising the sea level -- is still unclear, but Dr Guglielmin said tests on the sample from the seabed should be able to gauge the period fairly accurately.

The tests will be carried out at Insubria University in the Italian city of Varese, where Dr Guglielmin works. The discovery of the underwater permafrost came as part of a programme of research being carried out by this summer's Italian scientific expedition.

- NZPA