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Victoria University Antarctic Research Expedition Science and Logistics Reports 2001-02: VUWAE 46

Arena Valley

Arena Valley

In contrast to Beacon Valley, Arena Valley has little polygonal ground and is mostly underlain by a bedrock of Ferrar Dolerite and Beacon Supergroup sediments. Elevations of the main valley floor are about 200 m lower that Beacon Valley and lie between 1100 and 1300 m. Winds, generally down valley, were 10 – 15 knots stronger than Beacon Valley during the field visit and probably averaged between 15 and 25 knots. Our camp was located at the western end (generally the leeward end) of a linear snow patch at the northern edge of Ashtray Basin (1130m; S77°51.593′ E160°56.915′) and was selected for the snow patch and central location to the valley. Wind strength and duration at this location was about average for the valley floor.

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Most soils in Arena Valley have developed directly on bedrock but in some areas they have developed on talus and scree which have slid off steep valley sides. Except for the terminal moraines marking the retreat of the Taylor Glacier at the mouth of the valley, there are no glacial deposits in the valley. Polygonal ground probably covers less than 10% of the area of the valley bottom and slopes, and appears to be restricted to talus and scree deposits. This would suggest that the lack of polygonal ground in Arena Valley is due mainly to the lack of loose material upon which it can develop. However, local climatic conditions cannot be excluded because most of the polygonal ground also appears to be in areas of increased moisture and snow accumulation. In addition, the overall windy nature of the valley may remove much of the moisture making polygonal ground more difficult to develop.

In addition to talus and scree, polygonal ground was also found to form on sand dunes climbing up the sides of the valley (sites AV-4-6). Pits in the terminal moraines of the Taylor Glacier, showed muds and silts with horizontal bedding that suggests small lakes or ponds originated from glacial meltwater.

Soils in Arena Valley should be relatively older than those in Beacon Valley because of the mobility of polygonal ground that would homogenize soils rather than promote horizonation. Therefore, soils in Arena should be more horizonated both chemically and physically than those in Beacon Valley. Most pavement surfaces in Arena are similar to that apolygonal ground which is found on the southeastern flank of Beacon Valley with well-sorted pebble sized and highly ventifacted pavement surface. The main question in Arena Valley is why there is such an absence of glacial deposits when the adjacent Beacon Valley has been so highly glaciated. In addition, why is polygonal ground absent from the few glacial deposits that are present in Arena Valley.