Antarctica The Continent

The area of Antarctica is 13.97 x 10 km making it the fifth largest of the seven continents (Stonehouse 2002). It is conventionally oriented on maps as shown in Fig. 2.1 and is subdivided into East Antarctica, West Antarctica, the Antarctic Peninsula, and certain islands that rise more than 500 m above sea level (i.e., Alexander, Bear, Berkner, Roosevelt, Ross, and Thurston). In addition, Antarctica is surrounded by the Ross, Ronne, Filchner, Riiser-Larsen, Fimbul, and Amery floating ice shelves as well as by the Larsen ice shelf located along the east coast of the Antarctic Peninsula. Except for the northernmost tip of the Antarctic Peninsula, the continent lies within the Antarctic Circle at latitudes greater than 62.5° south. 

The continuing exploration of Antarctica has uncovered several natural phenomena that have not been recognized elsewhere on the Earth. All of these phenomena, which are mentioned here in passing, are described in detail in the appropriate chapters of this book  

The stratosphere over Antarctica is depleted in ozone because of the release of chlorine-bearing gases (CFCs) by humans in the mid-latitudes of the Earth. 

Large meltwater lakes that exist at the base of the East Antarctic ice sheet may be linked by subglacial streams of liquid water. 

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Tar sands have been reported on every continent except AustraHa and Antarctica. The best known deposits are the Athabasca of Canada, where almost 60,000 km in northeastern Alberta is underlain with an estimated 138 x 10 (870 x 10 bbl) of recoverable bitumen (157). The Alberta deposits... 

These Permian coals, together with counterparts in India, South Africa, Antarctica and South America, are referred to as Gondwana coals after the hypothetical super-continent which subsequently broke up into the continents and sub-continents mentioned above (5). ... 

Fig. 1.11. The development of the large, major continents (a) today (b) > 200 x 106 years ago (c) 120 x 106 years ago. Fragments of the original supercontinent are the continents we know today a, North America b, Asia c, South America d, Africa e, India f, Antarctica and g, Australia.

The southern flank of the upwelling CDW sinks around the continent of Antarctica to become AABW The northern flank of upwelling CDW is transported by surface currents, first into the polar frontal zone (PFZ) where AAIW forms, and then into the subantarctic zone (SAZ ) where SAMW forms. At these latitudes, dust deposition is high enough to reduce iron limitation of the diatoms. As the surfece waters move northward. 

The neritic sediments surroimding the continent of Antarctica are dominated by glacial marine deposits. Divergence at 60°S causes oceanic upwelling, which transports cold, nutrient-rich waters to the euphotic zone. Since diatoms are the dominant phytoplankton, diatomaceous oozes encircle Antarctica between the latitudes 50° and 70°S. 

Tar sands have been reported on every continent except Australia and Antarctica. The best known deposits are the Athabasca of Canada, where almost 60,000 km2 in northeastern Alberta is underlain with an estimated 138 x 109 m3 (870 x 109 bbl) of recoverable bitumen (157). The Alberta deposits may contain up to 215 x 109 m3 (1350 x 109 bbl) of bitumen reserves. Venezuela may have the largest accumulations in the world the Orinoco heavy-oil belt has been estimated by some (157) to contain as high as 636 x 109 m3 (4000 x 109 bbl). The Olenek reserves in the former USSR may contain ca 95 x 109 m3 ( 600 X 109 bbl). The United States is estimated to have deposits of about 4.5 x 109 m3 (28 x 109 bbl). 

Larks are 75 species of small, terrestrial songbirds that make up the family Alaudidae. Larks breed on all of the continents except Antarctica. Their usual habitats are all open areas and typically include prairies, savannas, alpine and arctic tundras, heathlands, and some types of agricultural fields. 

Oystercatchers are six rather similar-looking species of oceanic shorebirds that comprise the family Haematopodidae. Oystercatchers occur widely on subarctic, temperate, and tropical seacoasts, on all of the continents except Antarctica. 

The Antarctic ice cap represents the largest water reservoir on the earth if totally melted, this huge ice volume (about 3 x 10 km ) would raise the world ocean level by several tens of meters. The mean annual temperatures range from about -10°C on the coast to below -55°C in the central part of the continent. Antarctica is one of the driest places on Earth, with annual precipitation rates amounting to only a few centimeters of water equivalent per year. 

The Antarctic Treaty and the Madrid Protocol provide the necessary framework for environmental management and have obliged all the nations with an active presence in the continent to reduce their impacts on the antarctic environment. The Treaty s aim is to guarantee the peaceful use of Antarctica and to ensure conservation of flora, fauna and the natural environment. Through more adequate environmental impact assessment and management as well as environmental monitoring it is expected the Antarctic will remain the cleanest place on earth despite an increase in human presence. 

The availability of ad hoc CRMs can substantially contribute to the credibility and comparability of experimental information obtained in Antarctica. The global investment made in this remote continent in terms of human and financial resources, and the crucial role played by Antarctic studies in the interpretation of phenomena on a planetary scale do demand that no questionable data be generated or circulated. It would be thus desirable that other countries undertake similar programmes and stimulate the major producers of CRMs to support and participate in such initiatives. International planning and coordination in this context will definitely provide additional evidence of Antarctica as being as a land of peace and science. 

The map in Fig. 2.4 reveals that known tungsten deposits are scattered over all the continents with the exception of Antarctica. The various types of these deposits can be assigned to three macrotectonic units Precambrian, Paleozoic orogenic belts, and Mesozoic-Terdary orogenic belts. 

Growth of the Antarctic ozone hole, located mostly over the continent of Antarctica, since 1979. The images were made from data supplied by total ozone-mapping spectrometers (TOMS). The color scale depicts the total ozone values in Dobson units. The lowest ozone densities are represented by dark blue. 

Basically, it can be stated that the sedimentation rate decreases with increasing distance from a sediment source, may this either be a continent or an area of high biogenic productivity. The highest rates of terrigenous mud formation are recorded on the shelf off river mouth s and on the continental slope, where sedimentation rates can amount up to several meters per one thousand years. Distinctly lower values are observed at detritus-starved continental margins, for example of Antarctica. The lowest sedimentation rates ever recorded lie between 1 and 3 mm ky. and are connected to deep-sea red clay in the offshore deep-sea basins (Table 1.7), especially in the central Pacific Ocean. 

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