by Yuri AVSYUK, Corresponding Member of the Russian Academy of Sciences, Head of Gravitation Laboratory of the Otto Schmidt Institute of Physics of the Earth, RAS
In February 2006 the Oktyabrsky Hall of the House of Unions in Moscow brought together participants in expeditions to Antarctica on the occasion of the 50th anniversary of the beginning of regular all-round investigations of Antarctica by our scientists.
Yuri AVSYUK - the participant of the 3rd Antarctic Expedition in 1957 - 1959, navigator of the caterpillar tractor train which in 1958 reached [he so-called Pole of Relative Inaccessibility being at a height of 3,720 m and in 660 km from the South Pole - Ed.
The meeting of people who have touched the secrets of the Blue Continent has become a pleasant and impressive event. Each of them kept memory of the things seen in the past and, first of all, the inimitable pictures of nature-majestic icebergs, gigantic penguin colonies, snowstorms, long sunny days and the nights with the aurora australis.
The main investigations of Antarctica started on February 13, 1956, when the Mirny geophysical observatory was founded on the coast of the Davis Sea. It was the first Soviet expedition to Antarctica. Mikhail Somov. a well-known oceanologist and polar researcher, was appointed head of the expedition. Of course, at that time nobody knew what this huge area is looking like-whether it is an archipelago of icy islands or mainland lost in the ice?
That became clear during our expeditions, when the trailblazers repeatedly passed the most difficult snow tractor routes-coastline and almost to the center of the Earth's South Pole. As a result it was found out: Antarctica with an area about 14 mn km2 , i.e. greater than the territory of Europe, is a mainland which had been gradually covered with ice since the Oligocene (35 - 40 mn years ago). The ice mass, having reached a maximum of approximately 4,000 m, loaded the underlying blocks of the Earth's crust and, in time, the ice settled deep down: the so-called isostasy was realized*. This phenomenon is not an assumption; it was established on
* Isostasy - the accumulation of weight of ice masses that conduces ю submersion of the entire blocks and lo shift of the underlying Earth's crust materials. - Ed.
the basis of gravity anomalies registered during the investigations*. By the way, scientists started to tell about such a phenomenon in the nineteenth century, after the survey operations in the Himalayas. Later on, the gravity measurements in Fennoskandia** confirmed this fact. Now the subglacial relief of Antarctica is known in a broad outline. Many of its structures have received the names of our eminent scientists. The coastal mountains 800 to 900 m high, embedded under the ice to the south of the Pravda Coast (between 67° to 70° southern latitude), bear the name of Boris Golitsvn, member of the St. Petersburg Academy of Sciences, physicist and geophysicist, one of the founders of seismology (1802 - 1916). Next there is a subglacial plain there named after Otto Schmidt (1891 - 1956), Vice President of the Academy of Sciences of the USSR, major organizer and participant of the opening of the Northern Sea Route. The icesheet covering the plain is 3.500 m in thickness. To the south the plain passes into mountains named for academician Grigory Gamburtsev (1903 - 1955), who made a considerable contribution to the development of the seismic theory, and Vladimir Vcrnadsky (1863 - 1945). the founder of geochemistry, biogeochemistry and radio geology. The mountains reach 3,000 m in height and their cross-section is traced from 75° of the southern latitude.
* See: V. Kotlyakov, "Antarctica Reveals Its Secrets", Science in Russia, No. 1, 1997. - Ed.
** Fennoskandia - a natural land to the north of Europe, in the territory of the Scandinavian and Kola Peninsulas, ahout 1.5 mn km2 ; its uplands and flatlands bear traces of glaciation. - Ed.
Each of the fragments of the materials obtained during the research of Antarctica relief forms, both surface and embedded under the ice, established during the snow tractor campaigns of different expeditions starting from the 2nd Expedition (1957) proved the isostat-ic balance of this continent and allowed evaluating the thickness of the Earth's crust-from the Mirny geophysical observatory to the station of the Pole of Relative Inaccessibility.
Simultaneously, a seismologic monitoring elicited an interesting fact: no earthquake with a center within the limits of the continent was registered in Antarctica. This interesting geophysics phenomenon requires further explanation.
Carrying out seismic sounding in the region of the Vostok station (heart of the continent at a height of 3,740 meters above sea level), our colleagues detected a large freshwater nonfreezing lake 260 km in length, 50 km in width with water thickness up to 600 meters. Of course, such an object immediately captured close attention of specialists: soon works on drilling through the whole mass of ice sheet and study of the complicat-
ed structure of freezing water, were started, as it was proved that the bottom ice is close to the temperature of the melting point. However, in 1998, after the depth of 3,623 meters was reached, it was decided to stop the works as the sudden disruption of insularity of the lake's life and fauna could destroy the interesting source information on climatic changes over the last 420 thousand years. Now microbiologists, geographers and geophysicists try to find variants of safety contacts of drilling equipment with the biota* of this lake. By the way, lately, similar lakes were also found in other areas of Antarctica.
The detection of a change of the ozone hole dimensions over the ice continent became a sensation as well. It is established that it begins to grow during the Antarctic spring (September, October) and then gradually turns weak and dissipates. This phenomenon is presently actively discussed by scientists: the depletion of the ozone layer is caused by the critical pollution of the atmosphere by carbon dioxide.
Meteorologists and aerologists have made numerous discoveries as well. In particular, they have determined the air mass circulation over Antarctica, measured the variation range of wind strength and temperatures over different areas of the Blue Continent. Thus, the floor of -89.2°C (1983) was registered at the Vosiok station. This area received the name "the Cold Pole". In summer, the temperature on the coast of Antarctica ranges from if to +5°C and in winter from -8° to -35°C. Strong winds blowing in the high latitudes on certain areas, mainly in one direction, create a peculiar surface relief, i.e. snow ice hummocks up to 1 meter high. They have the shape of a streamlined wing and incredible hardness capable of standing even against a heavy tractor.
* See: V. Kotlyakov, "Environment, Its Past and Future: Glaciology Bears Witness", Science in Russia, No. 1, 2001. - Ed.
Some time ago investigators detected a considerable air and water temperature fall near the southern coasts of Antarctica. It is known that around it, one of the ocean currents - the Antarctic subpolar current-goes east. It creates a global ocean circulation since all the largest world water basins adjoin it in the south. Cold water of the high southern latitudes submerges to the depths of the ocean and is being replaced with warm water. Such a rotation sustains a relevant climate, shifts sea ice away from the continent, and in summer most of it thaws.
It is obvious that it is impossible to tell about all investigations of Antarctica in a short story, the more so, as they do not stop even for a day. We expect ever new discoveries of Russian scientists who have self-lessly been working for half a century now in the interests of science and man under most arduous conditions.
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