Desarrollo de la Antártica

TakeS'Í Nagata ¡ THE ADVANCEMENT OF SCIENTIFIC RESEARCH ••• Africa, could be good examples of hopeful mines of mineral resources in Antarctíca in the future. b) Antarctic Glacial History It was known even before the IGY from geomorphologícal studies on glacial-eroded rocks that the Antarctic ice-sheet was considerably larger in the past than in the presento Systematic geomorphological and glaciological studies starting in the IGY have revealed the ~ladal history of Antarctica. For example: 1. Multiple glaciations (four times) took place in McMurdo area in the past; 2. The ice sheet on the west side 01 Transantarctic mountains was dIe largest over 400 million years ago; 3. Ross ice shelf was expanded owing to tJhe glacial eustasy when I:he northern hemisphere was subjected to the cold climate; 4. The sea water was extended into Dry Valley area in Southern Victoria Land in Pliocene and Miocene, etc. Marine terraces and raised beadhes along the Antarctic coast are indicating tille recent crustal movements in association of develop– ments and diminutions of the Antarctic ice sheet. On the other hand, banks in Ross sea may represent the moraines produced when the larger ice sheet covered the Antarctic continent. These geomorpho– logícal and geological studies in detail on exposed rack areas of '\.nt. arctica and the (f\ntarctic continental shelf may reveal the recent geological history of Antarctíca in association with changes of tlhe Antarctic ice sheet. § 7. OCEANOGRAPHY IN ANTARCTICA Physical and chemical oceanagraphies of the Antarctic Ocean (or the Southem Ocean) surrounding the Antarctic continent have been reasonably well developed, because the topography of Antarctic continent and its geographkal relation with other continents are comparatively simple. Namely, except Drake passage between the soutlhern end of Soutlh America and the northem edge of Antarctic Península, the Antarctic continent of an approximately circular shap'e is surrounded by large oceans without any serious disturbance on ocean currents. a) Antarctic ocean CUirr~nts The sea water in the Antarctic ocean (which Cüuld be defined as the ocean south of 559S latitude circle) can be conventionally classified