Iceberg drifts off island south of Australia

updated 4:48 p.m. ET Nov. 12, 2009

SYDNEY - A large iceberg was spotted off an island about halfway between Antarctica and Australia, a rare sight in waters so far north, Australian scientists said Thursday.

Australian Antarctic Division researchers working on Macquarie Island, about 930 miles southeast of Tasmania, first saw the iceberg last Thursday about 5 miles off the northwest coast of the island.

The iceberg, about 160 feet high and 1,640 feet long, is probably part of one of several larger icebergs that broke off Antarctica's Ross Ice Shelf between 2000 and 2002, Australian Antarctic Division glaciologist Neal Young said.

Several icebergs have been drifting slowly northward with the ocean current toward the island over the past year, but it is uncommon for them to move so far into warmer northern waters, he said.

The scientists believe the iceberg will break up and melt rapidly as it continues its journey north. Before it melts, however, it could present a danger to ships navigating the region, Young said.

In 2000, several massive icebergs broke off from Antarctica's Ross Ice Shelf and the Ronne Ice Shelf. The first iceberg was about 190 miles long and 23 miles wide. Those icebergs are now drifting away from Antarctica.

Icebergs are formed as the ice shelf develops. Snow falls on the ice sheet and forms more ice, which flows to the edges, onto the floating ice shelves. Eventually, pieces around the edge break off.

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