The Antarctic Ocean Author

Subject : Earth Science Paper: Oceanography Topic: The Antarctic Ocean Author : Prof.A. Balasubramanian Objectives After attending this lesson, the user would be able to understand the importance of the Antarctic ocean, its geographic setting, geological conditions, its biodiversity and the natural resources. The reasons for protecting the Antarctic as an international zone of scientific research will also be known. The unique conditions of this fourth oceanic land mass will always be an interesting topic of study to the students of oceanography. 1.0 Introduction The earth is called as a blue planet mainly due to the presence of the bluish oceanic water masses. There are two white colored zones around the poles, denoting the presence of ice covered seas and continents. One is the Arctic ocean around the north pole and the other one is the Antarctic ocean around the south pole. The fourth major oceanic mass of the earth in the Antarctic ocean. It is a major oceanic land mass covered with continental ice sheets. It is one of the coldest regions in the world. The Antarctic is slightly colder than the Arctic region. Many geographers say that these waters do not form a separate ocean at all. They also advocate that the Antarctic is an extension of the southern parts of the other oceans like the Atlantic, Indian, and the Pacific. The Antarctic is also referred to as the Southern Ocean. The Southern Ocean refers to a ring of ocean that circles Antarctica. In this lesson the geological geographic and oceanographic details of the Antarctic Ocean are highlighted. 2.0 The Geographic Setting The Antarctica is centered asymmetrically around the South Pole. It is the southernmost continent in world. The 66 degree 34 minutes south latitude forms the outermost boundary of the Antarctic circle. The area covered within this circle is called as the Antarctic Continent. It includes parts of the Southern ocean, surrounding seas, ice shelves, continental glaciers, plateaus and mountain ranges. The Antarctica is the coldest, driest, and windiest continent, possessing many unique features to learn. 2.2 Dimension The Antarctic covers more than 14 million sq. km, making it as the fifth-largest continent, in the world. The coastline measures a length of about 17,968 km. The nearest continents to the Antarctic are, the South America, New Zealand, Australia and Africa. The shortest distance lies between Cape Horn of South America and the Palmer Peninsula of the Antarctic. The Antarctic Peninsula is a mountainous, S- shaped finger of land that points toward South America. In fact, this peninsula forms a continuation of the Andes Mountain chain of South America. 2.3 Ice covered land About 98% of the Antarctica is covered by ice, which averages at least 1.6 km in thickness. The name Antarctica is a Greek word. It bears a feminine meaning as "opposite to the north". It is almost like anti- arctic or opposite to arctic. About 98% of Antarctica is covered by only ice sheet, averaging at least 1.6 km in thickness. The continent has about 90% of the world's total ice. It contains about 70% of Page 1 of 9 the world's fresh water resource. If all of this ice were melted, the global sea levels would rise to about 60 m. 2.4 Two major regions The Antarctic land mass has a stretch of mountains called as Trans-antarctic Mountains. This divides the Antarctica into two regions. The portion west of this range is called as West Antarctica and east of it is called as East Antarctica. Both the regions have a lot of mountains, peaks, valleys, land provinces, massifs, ice-shelves, plateaus, coasts, bays and seas. 2.5 The East Antarctica The East Antarctica lies on the Indian Ocean side of the Trans-antarctic Mountains. It comprises the Coats Land, the Dronning Maud land, the Enderby Land, the Mac Robertson Land, Princess Elizabeth land, Queen Mary Land, the Wilkes Land, the Terre Addie land, the George land, the Oates land and, the Victoria Land. The East Antarctica faces the Atlantic and Indian oceans. It covers more than half the continent. Mountains, valleys, and glaciers mark the coast of East Antarctica. The central part of the East Antarctica is a plateau raising upto 3,000 metres above sea level. 2.6 The Western Antarctica The Western Antarctica lies nearer to the South American continent. It comprises of the Ross Ice Shelf, the Marie Byrd land, the Ellsworth Land, the Palmer Land, the Ronne Ice Shelf, the Filchner Ice Shelf and the Graham Land. The West Antarctica borders the Pacific Ocean. 2.7 Prominent Mountains of the Antarctic The Prominent Mountains of the Antarctic are the Ellsworth Mountains, the Siple Mountains, the Mount Sidley, the Mount Nansen, the Mount Elster, the Mount Markham, the Mount Kishpatrik and the Mount Barr Smith. The South Polar Plateau is located around the south pole. The West Antarctica includes several other mountain ranges and volcanoes. The Vinson Massif, the highest point in Antarctica at 5,140 metres, stands in the Ellsworth Mountains near the peninsula. Mount Erebus, Antarctica's most active volcano, lies on the island. It rises upto 3,794 metres. 2.8 Rivers of the Antarctic Most of the rivers and small streams of the Antarctic are generated due to melting of the ice-fields. The glacial melt of the mountainous peaks are responsible for the surface flows in the streams and creeks. The notable streams are Adams stream, Alph River, Onyx river, Priscu stream, and Surko Stream. Priscu stream is the longest one extending upto 3.8 km. The notable creeks are Aiken creek, Lawson Creek and Rezovski Creek. The length of the creeks range from 0.5 km to more than 1.5 km. 2.9 Seas and Bays The Seas of the Antarctic are the Weddell Sea, the Indian Ocean, the Ross Sea and the Bellingshausen Sea. There are some notable bays existing around the Antarctic. They are the Amundsen Bay, the Edward VIII Bay, the Mackenzie Bay, the Farr Bay, the Vincerness bay, the Kainan bay, the Sulzberger Bay, the Pine Island Bay, the Marguerite Bay, the Hope Bay and the Lutzow-Holm Bay. 2.10 Land of Ice As per the geological records, it was found that the Antarctica was an ice-free continent, many millions of years ago. Scientists have found fossils of trees and of dinosaurs and small mammals that once lived in this landmass. Glaciers began to form around the south pole about 38 million years ago. They grew rapidly about 13 million years ago and formed a very thick layer of ice and snow known as the Antarctic icecap. The icecap has buried almost all of Antarctica for the last 5 million years. The icecap Page 2 of 9 is up to 4,800 metres thick. At its highest points, over mountain ranges, the icecap rises as high as 4,100 metres above sea level. 2.11 Ice sheets Today, the Antarctic icecap forms the largest body of fresh water in the world. Its volume of 30 million cubic kilometres represents the world’s 70 per cent of fresh water resources. The weight of the icecap causes the ice to spread outward and slide toward the coasts. Ice near the coasts moves as much as 200 metres a year. In some areas, the icecap breaks and forms crevasses (cracks) that are more than 30 metres deep. The thickness of Antarctic ice is almost 1.6 km. the average rate of thickening of ice is 0.9cm per year. These are distributed as Ice Sheets, Ice-Shelves, Ice rises and glaciers. 2.12 Islands There are numerous islands around the Antarctic. The notable ones are , Balleny Is land, Scott Island, Thurston island, Peter I island, Charcot Island, Adelaide island, Biscoe island, South Shetland Island, King George Island, Elephant Island, South Orkney Island, Coronation Island, Joinville Island, James Ross Island, Hearst island, Alexander Island and Berkner Island. 2.13 Coasts of Antarctica Two large gulfs cut into Antarctica at opposite ends of the Trans-antarctic Mountains--the Ross Sea and the Weddell Sea. Smaller bays indent the coastline. The notable Coasts of Antarctica are Princess Martha Coast, Princess Astrid Coast, Princess Regnhild Coast, Prince Olav Coast, Kemp Coast, Mac Robertson Coast, Wilhelm Coast, Queen Mary Coast, Knox Coast, Budd Coast, Sabrina Coast, Banzare Coast, George Coast, Hobbs Coast, Walgreen Coast, Eights Coast, Robert English Coast, Luit Pold Coast and Caird Coast. Most of the coastlines are ice shelves. 2.14 Ice shelf The Ross Ice Shelf is one of the largest one in the world. It measures about 700 metres thick at the inner edge and about 200 metres thick at the outermost edge. In summer, the outer edges of the ice shelves break away and form flat icebergs. Scientists have measured and studied the Antarctic icebergs. They found that the area covered by icebergs were found to be as huge as 13,000 square kilometres. Each winter, the surface of the Antarctic Ocean freezes into a sheet of ice. In summer, this sheet break s into pieces called ice floes. Winds and waves push the floes against one another, forming thick masses known as pack ice. Some pack ice piles up in ridges against the shore. In winter, pack ice may extend as far as 1,600 kilometres from the coast inside the ocean. 3.0 Historical Expeditions Initially, Long before Antarctica was discovered, the ancient Greek philosophers believed that a continent exists around the southern end of the earth. In 1772, the English navigator, James Cook began his search for this southern continent.

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