Antarctica, for the most part, is a lifeless continent of rock and ice. Over the last 15 years, scientists have come to believe that the stark and frigid landscape we see today has existed for a very long time; the climatic message embedded in sea sediments is that once an ice sheet enveloped East Antarctica 15 million years ago, it never let go.
Now, however, scientists working on the continent itself have uncovered the wooden remains of what they believe was an extensive forest that flourished only 400 miles from the South Pole about 3 million years ago.
The idea of a permanently ice-clad Antarctica first began to melt a few years ago when Webb, a paleontologist at Ohio State University in Columbus, and his co-workers discovered marine microfossils in the Transantarctic Mountains (SN: 7/2/83, p. 6). Webb concluded that 4 million years ago, as well as at earlier times, the ice sheet had retreated and seaways stretched across East Antarctica. Then, when the sheet advanced, it carried the fossils from the ocean basin to the mountains.
The new find of roots and stems of wooden plants and of pollen in an area stretching about 1,300 kilometers along the Transantarctic Mountains means not only that the ice retreated but also that the climate was warm enough to support a shrublike beach forest. "The presence of the wood means that there was deglaciation on a major scale, with conditions radically different than they are today," says David Elliot, chief scientist of the recent National Science Foundation polar expedition, of which Webb's group was part. "This is a very significant find." Webb thinks the forest region a few million years ago must have resembled the present-day fjords of Chile and Norway.
According to Webb, before the forest developed, the region was covered by a considerable amount of ice. So an important question is where the forest and pollen came from. "Had the forest been living there all the time, and are we overestimating the severity of the earlier glacial record?" he wonders. Had life developed on its own in Antarctica? Or had the plants and pollen been carried to Antarctica from other continents?
Webb notes that 40 million years ago, Antarctica was the middle link in a migration path for marsupials and other life traveling from South America to Australia, when both continents were much closer to Antarctica. By a few million years ago, Australia had moved very far away from Antarctica, so that "any migrations that took place along the same route would have come to a rather disastrous end," he says. "However, in my wilder moments I think that Antarctica may have received these migrations from lower latitudes." Just in case, Webb's group is on the lookout for remains of insects and other creatures that might have lived in the Antarctic forest.
In addition to finding evidence that the recent glacial history of Antarctica is more dynamic than was previously thought, Webb's group concluded that the continent may have been more tectonically active as well. The researchers discovered that the deposits containing the wood fossils are sliced by faults, which displaced sediment layers by as much as 1,000 meters. This indicates that the Transantarctic Mountains have risen very rapidly in the last few million years. Previously scientists had assumed that they had risen slowly, over a 40-million-year period.
