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Victoria University Antarctic Research Expedition Science and Logistics Reports 2002-03: VUWAE 47

Table Mountain

Table Mountain

The Table Mountain camp site was chosen close to the temperature probes on a patch of snow at S77°57.631′ E161°57.324′, altitude 1850m. We experienced winds of up to 40 knots with the temperatures remaining relatively constant around –18 °C.

On the floor of Columnar Valley (adjacent to Table Mtn) polygons have a diameter of 4-10 m and <1 m height differential between trough and polygon centres. Polygons extend from the valley floor up the valley walls up to slopes dipping up to 25° right to the debris flow boundary. The distribution and appearance of the surface material of the polygons in Columnar Valley varies with some polygons having a "brick wall-like page 4 appearance with whilst others were covered by randomly distributed boulders and cobbles of varying sizes.

Six pits were dug in total and in all pits permafrost was encountered at depths between 7 and 16 cm. Three pits dug in the cracks between the polygons contained clear ice at depths between 14 and 23 cm. The permafrost boundary appears to follow the surface topography of the polygon.

In general, the activity of any single polygon or part of it may be reflected by the distribution of the material in the troughs. Parts of troughs are flat having been filled with sand while other parts are steep and rocky with angular cobbles and boulders. This angular material may be sorted or unsorted. On the active part of a polygon, clasts may roll off the steep sides and into the trough. Sorting of clasts in the trough may occur by what the center crack is able to accommodate. On the inactive part of a polygon, wind blown sand may accumulate in the trough. This observation suggests that polygon activity may be dynamic so parts of it are active while at the same time other parts are inactive.

A major problem apparent from the fieldwork is to understand what controls the age of the surface and the relationship to polygon development in Columnar Valley. Alternatively, it may be the ice content below the surface that controls polygon development. Soil development and age may be more of a function of the material, aspect and moisture regime, rather than the depositional age of the material in which the soil is forming.