Antarctic Oases

portions of the fringe zone of the antarctic continent that are free of ice cover. The term is applied by analogy to oases in deserts in view of the more favorable conditions prevailing there for the development of life. Area, several dozen to several hundred square kilometers. Located in regions of glacial accumulation and surrounded by an ablation zone, antarctic oases exhibit a specific natural complex (local cold desert climate, existence of water in liquid phase for most of the year, abundance of lakes, organic life, and primitive cryogenic-structured soils). Antarctic oases are subdivided into typical low-mountain and hilly valleys (for example, Bunger, Westfall, Grierson, or Schiermacher), intermontane (dry) valleys (Taylor, Wright), and high mountain oases (Rieser-Larsen, Brendvognip). The native rock of antarctic oases is predominantly gneiss and crystalline schist subjected to extensive physical and chemical weathering. Iron-manganese varnish and desert varnish impart a reddish-brown coloration to the oasis rocks. Traces of ice sheet glaciation are found everywhere (polished rocks, glacial striation, moraines). Antarctic oases show a positive annual radiation balance (1.0–1.7 gigajoules per sq m per year, or 25–40 kilocalories per sq m per year). The average annual air temperature at the oases is 1°-2°C warmer than in the surrounding territories. (This difference may be as great as 5°-6°C in the summer.) The stony surface of antarctic oases can reach a temperature of 40°C. Precipitation in the form of snow amounts to 200–300 mm, most of it thawing and evaporating. Flora and fauna are very sparse. Some species of mosses and lichens, soil algae, and freshwater algae exist. Birds that nest at these oases include the stormy petrel and the skua; Adélie penguins roost at some oases. The term “oasis” as applied to antarctic conditions was first suggested in 1938 by A. Stefansson, who participated in J. Rymill’s expedition to the antarctic.