489

Site number:

489

Authors:

IBC, GGC

Date recorded:

1983/01/07

Reason Sampled:

Permafrost weathering examination

Description:

2km N of Mt Brooke on the floor of an old undulating glacially eroded valley; the surface is uneven with a broad hummock and swale topography with small scattered snowbanks; the site is about 100m W of site 488, on an undulating surface that is about 20m above the valley floor; the site is on the upper edge of a small hummock

Altitude:

2220 m

Aspect:

Slope:

0 °

Climate

Soil climate zone:

central mountain

Estimated mean annual temperature:

-32 °C

Frozen ground depth:

40 cm

Frozen type:

Hard ice-cemented

Frozen comment:

40cm

Geology

Geological setting:

Outcropping rocks on Mt Brooke and adjacent hills include Jurassic tuffs and lavas, Ferrar Dolerite and Beacon Group sediments; the drift mantle on the valley floor is continuous but appears to vary in weathering and age from place to place; on this slightly higher surface, soil development appears greater than in soil 488

Patterned ground:

Well developed 10-15m nets with raised centres and troughs up to 1m deep

Surface weathering or surface features:

Surface boulders are up to 40cm across and are moderately stained and oxidised and show some exfoliation and pitting on upper surfaces; salt weathering is occurring beneath surface stones where they are in contact with the soil

Soil

Soil parent material:

Till derived from dolerite, tuff and sandstones

Previous disturbance:

Nil

Soil weathering stage:

6 3 (Campbell & Claridge 1975)

Soil moisture status:

Xerous, recent widespread 3.5cm snowfall but negligible thawing

Biological activity:

Nil observed