Approximately 2.6km NNE of Mt Brooke on the floor of a valley; the site is on the S edge and on the eastern side of a low valley floor ridge, which has the appearance of a gravel dune;
Altitude:
2000 m
Aspect:
W
Slope:
4 °
Location Data
Observer
GGC
IBC
GPS
No
Latitude Longitude DMS
76° 48.5' S 159° 54.7' E
76° 47.9' S 159° 55.2' E
Latitude Longitude DD
-76.808 159.9117
-76.7983 159.9200
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
1
12.8
10
5.5
20
3
30
0
40
-3
50
-6
75
-10
Estimated mean annual temperature:
-32
°C
Frozen ground depth:
30 cm,
Frozen type:
dry frozen
Frozen comment:
30cm,
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; although the land surface has a mega ripple, low dune-like surface, the deposits have no dune like characteristics
Patterned ground:
nil at site but some weakly developed patterned ground in swales between low ridges
Surface weathering or surface features:
Strongly developed pebble and cobble pavement; doleritic clasts are subrounded and weakly ventiform; some deep fine pitting on larger boulders; surface polish well developed
Soil
Soil parent material:
Dominantly dolerite till but with the fine fraction from the more erodible haloclastite; till, possibly modified during deposition and or ablation by wind sorting; the lower part of the profile may be a paleosol
Xerous; several snowfalls but little thawing or soil moistening; small snow patches nearby
Biological activity:
nil observed at site
Profile Description
Horizon
Depth
Description
800a
-3
–
0
cm
surface pebbles and cobbles; well developed pavement; subrounded to subangular; most clasts dark, polished and unstained but some are moderately to strongly stained; salt accumulations beneath some stones,
800b
0
–
3
cm
strong brown (7.5YR 5/6) sandy pebble gravel; loose; rock particles subrounded with some moderately altered with some reddish oxide coatings; distinct boundary,
800c
3
–
17
cm
strong brown (7.5YR 5/8) pebbly gravelly sand; moderately to strongly cohesive; many salt flecks around stones; rock particles subrounded to subangular and unstained with some moderately altered; distinct boundary,
800d
17
–
27
cm
yellowish red to strong brown (5YR 5/8 - 7.5YR 5/8) gravelly sand; firmly cohesive and strongly salt cemented; rock particles subangular to subrounded with some partly altered; distinct boundary,
800e
27
–
46
cm
brownish yellow (10YR 6/8) sandy pebbly gravel; loose; moderately cohesive; many distinct salt flecks; rock particles subrounded to subangular with some weak oxide staining; distinct boundary,
800f
46
–
55
cm
light yellowish brown (2.5Y 6/4) sandy gravel; firmly cohesive; abundant almost continuous diffuse salts; rock particles subangular and unstained; sharp boundary,
800g
55
–
70
cm
brownish yellow (10YR 6/6) bouldery gravel; moderately cohesive; abundant salts; rock particles subangular and unstained with some granular disintegration and weak ghost formation; indistinct boundary,
800h
70
–
90
cm
olive yellow (2.5Y 6/6) bouldery gravel; weakly to moderately cohesive; some salt accumulations; patches of oxide staining around some clasts; rock particles subrounded to subangular with some moderately stained; indistinct boundary,
800i
90
–
120
cm
olive yellow (2.5Y 6/6) bouldery gravel; weakly cohesive; few patches of salt; rock particles subangular to subrounded with some partly stained; indistinct boundary, on loose bouldery gravel