The Antarctic dilemma: blowing in the wind.

Sitting high and dry in the middle of a vast, icy continent, the South Pole is a strange place to find ocean algae. So when Davida E. Kellogg and Thomas B.

Kellogg found the shells of diatoms in a South Pole ice core some 1,200 kilometers from the nearest open ocean, they reasoned that the algae must have hitched a ride on the wind to the remote Antarctic site.

The discovery provides some potentially heartwarming news for anyone concerned about the possibility of Antarctica's melting away. The work calls into question suggestions that the great ice sheet shriveled during a warm episode in the recent geologic past, says Davida Kellogg. The researchers, both at the University of Maine in Orono, report their findings in the February Geology.

Close to 90 percent of the ice in Antarctica lies in the eastern part of the continent. If this East Antarctic ice sheet melted, it would swell sea levels by 60 meters, enough to drown parts of New York and many other coastal cities.

Most climate experts regard East Antarctica's ice as a remarkably stable feature that has persisted for at least 14 million years. In the mid-1980s, however, a small group of scientists from Ohio State University in Columbus undermined that staid reputation. They claimed that much of Antarctica melted away 3 million years ago, during a warm period in the Pliocene epoch.

The Ohio group's evidence comes in the form of tree fossils and sedimentary deposits left by bodies of water that at some time covered parts of now icebound Antarctica. The tree fossils could not be dated. But by dating marine diatoms found within the so-called Sirius group sediments, the scientists deduced that the trees lived less than 3 million years ago. According to their theory, the ice sheet melted during the Pliocene warmth, trees thrived, and then the ice formed again.

The Maine researchers propose another explanation for the Sirius group diatoms. If the wind blows algae across Antarctica, then the 3-million-year-old species could have dropped on much older sediments containing the tree fossils. "[Our work] does cast doubt on the warm Pliocene model," says Davida Kellogg.

Last year, another group reached similar conclusions after finding 8-million-year-old ice within a valley in East Antarctica (SN: 8/5/95, p. 87).

"There's now going to be a lot more doubt about the diatoms in the Sirius group deposits," admits David Harwood of the University of Nebraska in Lincoln. Despite the new evidence, Harwood and his coworkers at Ohio State continue to support the idea of a Pliocene meltdown.

To help resolve the debate, he and his colleagues collected additional samples of Sirius group rocks during the recent Antarctic field season. By looking below the surface, they hope to determine whether the diatoms were windborne.

The answers will not come quickly, though. The laborious process of identifying the diatoms may take a year.