798

Site number:

798

Authors:

IBC, GGC

Date recorded:

1995/01/10

Reason Sampled:

Permafrost and soil moisture investigations

Description:

Approximately 2.3km NNE of Mt Brooke on the eastern side of a valley on an undulating bench like surface about 150m above the valley floor; the sample site is on the edge of a small broad knoll

Altitude:

2190 m

Aspect:

W

Slope:

2 °

Climate

Soil climate zone:

Central Mountain

Estimated mean annual temperature:

-32 °C

Frozen ground depth:

0 cm

Frozen type:

hard ice cemented

Frozen comment:

ice-cemented at 50cm

Geology

Geological setting:

Rocks of the area are dominantly dolerite/volcanic (doleritic but dark coloured, fine grained and with a somewhat vesicular form compared with usual dolerite) and softer 'haloclastite', (earlier described as tillite); the haloclastite contains basement rocks, dolerite and sandstone clasts with sedimentary structures in places; it is softer and more erodible than the dolerite; the till cover across the area is quite variable and is generally thinner towards Mt Brooke and towards the higher ridges; the till mantle has an undulating surface across the landscape with a mega-ripple appearance which may relate to the manner in which the ice sheets have retreated and ablated, rather than to subsequent landscape modification by wind

Patterned ground:

indistinct and weakly developed, possibly old patterned ground crack 4m away from the description site

Surface weathering or surface features:

Doleritic clasts are subrounded and weakly ventiform; some deep fine pitting on larger boulders; some clasts strongly stained but most unstained but with dark well polished surfaces; well developed pavement of granules, pebbles and cobbles; exfoliation or cavernous weathering is absent

Soil

Soil parent material:

Dominantly dolerite till on ice cemented ground, but with the fine fraction from the more erodible haloclastite;

Previous disturbance:

nil

Soil weathering stage:

6 4 (Campbell & Claridge 1975)

Soil moisture status:

Xerous; several snowfalls but little thawing or soil moistening; small scattered pockets of snow near the site

Biological activity:

nil observed at site