The Antarctic plate, like other parts of Gondwanaland, is formed mainly from Precambrian to Lower Paleozoic basement rocks, intruded by granites and peneplained by weathering and glacial erosion with overlying sediments of sandstones, siltstones, coal measures and tillites. Jurassic basic igneous rocks were intruded to form widespread sills. Other more recent volcanics occur along major orogenic zones. The present glacial environment is believed to have established after the separation of Antarctica from South America which allowed the formation of a circumpolar circulation pattern.
Antarctic soils and permafrost occur in a geological setting where the time scale for landform development and weathering processes extends back to the Miocene or earlier, and in which the glacial events responsible for till deposition are related to several distinct sources. They include glaciations related to the East Antarctic Ice Sheet, the West Antarctic Ice Sheet and to Alpine glaciers (Figs. 2.3a and 2.3b).
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