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 S side of a small low ridge forming the edge of a small basin or shallow depression
Altitude:
2175 m
Aspect:
NNW
Slope:
4 °
Location Data
Observer
GGC
IBC
GPS
No
Latitude Longitude DMS
76° 48.5' S 159° 54.7' E
76° 48.1' S 159° 55.6' E
Latitude Longitude DD
-76.808 159.9117
-76.8017 159.9270
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:
No ice cement
Geology
Geological setting:
Rocks of the area are dominantly dolerite/volcanic (doleritic but dark coloured and with a somewhat vesicular form) 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:
some pitting on fine grained dark coloured dolerite, moderate to strong surface polish; weak to moderate ventifaction; pebble/cobble pavement is well developed
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; some patches of semi- permanent snow nearby
Biological activity:
nil observed at site
Profile Description
Horizon
Depth
Description
796a
-2
–
0
cm
well developed pavement of cobbles and pebbles; subangular to subrounded; weakly stained moderate to strong polish; salts beneath some surface stones,
796b
0
–
10
cm
strong brown (7.5YR 5/6) pebbly gravelly sand; weakly to moderately cohesive; scattered fine diffuse salts; rock particles subangular to subrounded; rock particles weakly stained but with mod. to strong internal alteration & yellowish red (5Y 5/8) oxide coatings on crushed faces of some clasts; indistinct boundary,
796c
10
–
20
cm
strong brown (7.5YR 5/6) pebbly gravelly sand; weakly to moderately cohesive; diffuse salts scattered through the horizon; rock particles subrounded and non stained but partly altered, distinct boundary,
796d
20
–
40
cm
strong brown (7.5YR 5/6) sandy gravel; moderately cohesive; abundant salt accumulations beneath and around stones; rock particles subrounded to subangular, unstained and partly altered, indistinct boundary,
796e
40
–
60
cm
strong brown to yellowish brown (7.5YR 5/6 -10YR 5/6) sandy cobble and pebble gravel; moderately cohesive; abundant salts; rock particles subangular and unstained; distinct boundary,
796f
60
–
80
cm
light yellowish brown (2.5Y 6/4) sandy cobble and pebble gravel; weakly cohesive; abundant diffuse salts; rock particles subangular and unstained; indistinct boundary,
796g
80
–
110
cm
light yellowish brown (2.5Y 6/4) bouldery to pebbly gravel; weakly cohesive; abundant diffuse salts; rock particles subangular and unstained; indistinct boundary,
796h
110
–
120
cm
light yellowish brown (2.5Y 6/4) sandy gravel; loose; indistinct boundary, on loose gravel