A keystone in a changing world - Antarctica: Global Science from a Frozen Continent - page 62

Figure 2.27 Ice towers formed over gas outlets on the side of Mt Erebus, an active volcano.

(Credit: Antarctica New Zealand)

Changing greenhouse icehouse worlds

-

During the time period 210 to 140 million years ago, climate was uniformly
warm to hot and wet worldwide, with a luxuriant cosmopolitan flora of conifers,

cycads, ferns, tree ferns, ginkgos and herbaceous lycopods and horsetails. Some of
the most spectacular fossil forests are preserved within 100million year old rocks on
the Antarctic Peninsula. Hundreds of fossil trees and shrubs are preserved in their
growth positions buried within sandstones that were deposited during catastrophic

floods from volcanic uplands. At this time, the trees were growing in latitudes as
high as 70ºS. It is thought that the plants tolerated the extreme polar light regime
by becoming dormant in the long dark winters and flourishing during the

summer days of midnight sun. The flowering plants

(angiosperms) 80million years ago marked a change in Antarctic vegetation. Many
fossil leaves are similar to those that live in subtropical climates today, indicating
that warm wet climates extended southward to cover Antarctica in much warmer

first appearance of fossils of