Approximately 2.2km NE of Mt Brooke and on the eastern side of the valley, on an undulating bench surface within glacial moraine cut topography; the site is on a near flat surface at the foot of a longer gentle slope
Altitude:
2180 m
Aspect:
Nil
Slope:
0 °
Location Data
Observer
GGC
IBC
GPS
No
Latitude Longitude DMS
76° 48.5' S 159° 54.7' E
76° 48.6' S 159° 54.1' E
Latitude Longitude DD
-76.808 159.9117
-76.8100 159.9020
Latitude longitude precision DD
0.004 0.0008
0.0008 0.0008
Locality
Coombs Hills, northern Dry Valley region and to the north of Mt Brooke
Survey
not recorded
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 22cm
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 formed an undulating ridge and swale 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; although the land surface has a mega ripple, low dune- like surface, the deposits have no dune like characteristics
Patterned ground:
Not present
Surface weathering or surface features:
A well developed pavement of pebbles, cobbles and occasional boulders; clasts subrounded to subangular; most are unstained but some coarser dolerite clasts are moderately oxidised; weakly developed ventiforms; salts beneath surface stones
Soil
Soil parent material:
Dominantly dolerite/volcanic till but with the fine fraction from the more erodible haloclastite over ice cemented ground at shallow depth
Xerous; several snowfalls and a recent fall within 36 hours also considerable drift snow; most snow cover removed by wind but patchy snow cover present at the sampling site
Biological activity:
Nil observed at site
Profile Description
Horizon
Depth
Description
804a
-30
–
0
cm
surface cobbles, pebbles, and granular sand; moderately to strongly developed pavement with subrounded to subangular clasts; some strongly stained, most unstained and polished; some altered with reddish oxide coatings on fractured faces; salts and calcium carbonate coatings beneath some surface stones,
804b
0
–
2
cm
strong brown (7.5YR 5/6) pebbly gravelly sand; weakly cohesive; weakly developed vesicular structure; rock particles subrounded to subangular, some stained and partly altered; distinct boundary,
804c
2
–
12
cm
strong brown (7.5YR 5/6) pebbly to cobbly gravelly sand; moderately to strongly cohesive and salt cemented; abundant diffuse salts; rock particles subangular to subrounded and some partly stained; sharp boundary,
804d
12
–
22
cm
strong brown (moist 7.5YR 5/6) gravel (drill core); hard ice- cemented ground; rock particles subrounded and unstained,
804e
28
–
40
cm
dark yellowish brown (moist 10YR 4/4) gravel (drill core); hard ice- cemented ground,
804f
40
–
50
cm
dark yellowish brown (moist 10YR 4/4) gravel (drill core); hard ice-cemented ground,
804g
50
–
70
cm
olive brown (moist 2.5Y 4/4) gravel (drill core); hard ice- cemented ground,
804h
70
–
83
cm
olive brown (moist 2.5Y 4/4) gravel (drill core); hard ice- cemented ground
804i
83
–
105
cm
grayish brown (moist 2.5Y 5/2) gravel (drill core); hard ice- cemented ground,
804j
105
–
120
cm
grayish brown (moist 2.5Y 5/2) gravel (drill core); hard ice-cemented ground