Desarrollo de la Antártica

Takesi Nagata / THE ADVANCEMEl'óT OF SCIENTIFIC RESEARCH •.• 4 x 104 in total number. The average area of an Antarctic icebergs is so large as 160 ikm 2 and their rlhkkness ranges mostly between 100 and 200 m. The three main source areas for the Antarctic icebergs are Ross Sea, Weddell Sea and Shackleton ice shelf. The icebergs ooming from these areas drift mostly subjected to the ocean ourrents because major parts of icebergs are below the sea surface. Hence, the Ant– arctic icehergs drift westward near the Antarctic coast owing to the westward 'Ocean current there but they do eastwardaround 6005 latitude drde or in the further north sea owing to illle eastward ocean currents in those latitudes. (See § 7). § 5. CARTOGIRAPHY IN ANTARCTICA a. PUlblished Antarctic maps • The cartography to construct maps of Antarctica should be the most fundamental basis [or tJhe devel'Opment 'Of any branch oí sdences and the utilization of this white continent. COInsequently every possible effort was made by alI Antarctic expedition parties to colIect geodetic and cartographic data of the l'Ocalities where they visited. During 30 years before ~he IGY, the vertical or oblique air-photo– graphies from air planes were the most powerful technique to get such cartographic data of Antarctica. :In these air-borne cartographic programs, (he most dífficulty was concerned wiúh the precise deter– minatíon of positi-Oins of the reference triangulation 'P0ints. The astoronomical position determination 01 base points and tihe triangulati'On network expanded {rom illl.ese base points to determine the positions of remarkable topo""oraphic marks (such as peak p'Oints of exposed mountains) together wíóh the air-photography surveys are the basic necessary works in these cartographic surveys. Recent technical development in the geodetic instruments suoh as fue electro– magnetic and laser geodemeters are extremely helpful in the laborious ge'Odetic w'Or<ks in Antarctica. Various cartographic maps of tlhe whole Antarctic area thus compiled hased 'On the air-phot'Ographs as well as on the results 'Of geodetic surveys carried out by t:he trans-'Antarctic traverse ~urveys have been publis:hed to date. They are as foll'Ows (Table 5) : Further, the larger scale maps of 1 : 1,000,000 '-' .1 : 100,000 in seale aho have been published f'Or the Trans-AntarctÍc mountain z'One and for the Antarctic coastal zone except Weddell sea coast. However, 1!hese large scale maps c'Over mostly narrow zones of about 400 km in width. 9 1