Geography Reference
In-Depth Information
the Equator, and layers of limestone, sandstone, and shale were deposited in tropical seas.
The eastern portion of Antarctica reveals fossil evidence of marine plants such as tropical
sponges. During the late Cambrian and Devonian periods (480 to 360 million years ago),
the super-continent migrated towards the southern hemisphere, and some of Antarctica's
oldest fossil plants found in the Trans-Antarctic Mountains have been dated to about 360
million years ago. In other areas of the polar continent such as Victoria Land, the fossil-
ized remains of marine life have been found.
As the super-continent experienced further cooling, so glacial deposits formed, and by
about 280 million years ago, Gondwanaland was located around the current location of the
polar continent. But the super-continent did not remain in a fixed position, and as it moved
again slightly northwards, so new flora and fauna emerged including fern-like plants, later
to contribute to the formation of coal deposits in the Trans-Antarctic Mern Ireland
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Some 90-85 million years ago, in the Cretaceous period, this rich and biologically diverse
super-continent began to disintegrate and transformed the southern latitudes. As Gond-
wanaland fragmented still further, the Atlantic, Indian, and Pacific Oceans were estab-
lished, and Australia alongside Antarctica migrated southwards. Some 30-40 million years
ago, Antarctica slipped even further south. This drift helped to cause the separation
between the South American Andes and the Antarctic Peninsula, and in the process this
tectonic schism created an oceanic passage later to be named the Drake's Passage. It is
only through major scientific investment, and the development of new techniques involving
geophysical and remote-sensing research, that we have a better idea of the underlying geo-
logy of the polar continent and Southern Ocean. The exact mechanisms of plate movement,
however, remain opaque.
The Antarctic continent possesses a series of important geological and morphological
characteristics. It is a continent surrounded by a ring of water - the Southern Ocean. Due
to the circumpolar current, waters circulate around the continent in a predominantly clock-
wise direction. There is a series of mountainous ranges, including those found on the Pen-
insula region, which are connected geologically to the South American Andes. Centrally,
the Trans-Antarctic Mountains weave through the centre of the continent from the Weddell
Sea to the north to the Ross Sea in the south. Divided into two distinct parts by the Trans-
Antarctic Mountains, the East and West portions of the continent were named for their re-
lative positions to the Greenwich meridian.
The immense Antarctic ice sheet, created over millions of years, without melting, covers
the polar continent. Due to pressure brought on by the sheer weight of 13 million square
kilometres of extent, the ice flows from the continental interior towards the coastline. Large
