Approximately 2km NNE of Mt Brooke on the eastern side of a valley on an undulating bench like surface about 100m above the valley floor; the sample site is on the crest of a small knoll
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° 48.2' S 159° 56.2' E
Latitude Longitude DD
-76.808 159.9117
-76.8033 159.9370
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
Site temperature profile
Depth (cm)
Soil temp (°C)
Notes
0
-6.7
Surface,
1
-8.9
15
-7.4
50
-8.6
75
-11
100
-11
Estimated mean annual temperature:
-32
°C
Frozen ground depth:
0 cm
Frozen type:
hard ice cemented
Frozen comment:
ice cement at 100cm
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:
nil at site
Surface weathering or surface features:
Doleritic clasts are subrounded and weakly ventiform; some deep fine pitting on larger boulders; some clasts strongly oxidised; surface polish well developed on dark coloured black dolerite; well developed pavement of granules, pebbles and pebbles with about 5% surface boulders; salts beneath some surface stones
Soil
Soil parent material:
Dominantly dolerite till but with the fine fraction from the more erodible haloclastite;
Xerous; several snowfalls but little thawing or soil moistening; most snow removed by wind and ablation; dry at site but some patches of semi-permanent snow 8m away
Biological activity:
nil observed at site
Profile Description
Horizon
Depth
Description
797a
-3
–
0
cm
surface cobbles, pebbles and granules forming a well developed pavement; some clasts strongly stained; patchy reddish oxide coatings in cracks; salts beneath some surface stones,
797b
0
–
1
cm
strong brown (7.5YR 5/6) pebbly and cobbly gravelly sand; loose; rock particles subangular to subrounded and predominantly unstained; distinct boundary,
797c
1
–
8
cm
strong brown (7.5YR 5/6) sandy pebbly cobbly and bouldery gravel; weakly cohesive; some patches of diffuse salts; rock particles subangular and unstained but some moderately altered; indistinct boundary,
797d
8
–
20
cm
strong brown to yellowish red (7.5YR 5/6 - 5YR 5/6) sandy pebbly to bouldery gravel; weakly cohesive; rock particles subangular and unstained with some moderately altered with reddish oxide accumulations; indistinct boundary,
797e
20
–
40
cm
light yellowish brown (10YR 6/4 - 2.5Y 6/4) sandy pebbly to bouldery gravel; moderately cohesive; many soft white salt flecks; rock particles subangular and unstained but some partly crumbled; indistinct boundary,
797f
40
–
60
cm
light yellowish brown (10YR 6/4 - 2.5Y 6/4) sandy pebbly to bouldery gravel; weakly cohesive; few fine salt flecks; rock particles subangular and unstained; diffuse boundary,
797g
60
–
80
cm
olive yellow (2.5Y 6/6) sandy pebbly to bouldery gravel; loose; rock particles subangular and angular and unstained; diffuse boundary,
797h
80
–
100
cm
olive yellow (2.5Y 6/6) pebbly bouldery gravel; loose; rock particles angular and unstained; sharp boundary,
797i
100
–
110
cm
light olive brown (moist 2.5Y 5/4) gravel; very hard and ice cemented