615

Site number:

615

Authors:

IBC, GGC, MRB

Date recorded:

1991/11/21

Reason Sampled:

Permafrost and soil moisture examinations

Description:

Approximately 4.4km NW of Marble Point peninsula and 450m W of the Marble Point Air Facility; about 40m from the Wilson Piedmont Glacier; on a surface that receives summer meltwater runoff as sheet flow during thaw; not a distinct stream channel

Altitude:

75 m

Aspect:

SE

Slope:

3 °

Climate

Soil climate zone:

Coastal Antarctic

Estimated mean annual temperature:

-18 °C

Frozen ground depth:

16 cm

Frozen type:

Hard ice-cemented

Frozen comment:

16cm

Geology

Geological setting:

The surface is a gently undulating till plain formed by retreat of the Wilson Piedmont Glacier; the Marble Point region is an old landscape, with deposits of phillipsite, buried soils and oxidised gneiss, which have been covered by advances of the grounded Ross Ice Shelf; later ice retreat and glaciological features have been controlled by changes in the stranded Wilson Piedmont Glacier; the till mantle is patchy and dominated largely by locally occurring rocks; granodiorite, granite, marble, gneiss, and dolerite are the main rock types present; sheet flow probably results in some minor sorting of the till deposits

Patterned ground:

Micro polygon nets

Surface weathering or surface features:

Larger clasts are angular to subrounded with some weak staining; some staining along cracks and veins; marble clasts actively crumbling; spalling in fine grained rocks is common

Soil

Soil parent material:

Sandy gravel till from mixed granite, gneiss and marble, with minor surface fluvial sorting

Previous disturbance:

Extensive mechanical and human activity in the region since the mid-1950's

Soil weathering stage:

1 (Campbell & Claridge 1975)

Soil moisture status:

Presently dry but moist with a thin surface water flow in some summers

Biological activity:

Dried cyanobacteria; scattered moss patches adjacent to larger boulders