The site is located on a ridge of moraine, several hundred m above the floor of Beacon Valley on the East side; this moraine ridge appears to block or infill an excavated cirque type small valley below Aztec Mountain; the moraine ridge is relatively narrow and drops towards the south; the ridge crest is flattish to undulating with patterned ground; the sampling site was near the centre of a PG polygon on the ridge crest,
Altitude:
1650 m
Aspect:
Nil
Slope:
0 °
Location Data
Observer
IBC
GGC
GPS
GPS
Latitude Longitude DMS
77° 48.84' S 160° 34.92' E
77° 48.84' S 160° 34.91' E
Latitude Longitude DD
-77.81400 160.58200
-77.81400 160.58183
Latitude longitude precision DD
0.00008 0.00008
0.00008 0.00008
Locality
Near the head of the Taylor glacier and close to Aztec Mountain in the McMurdo Dry Valley region; 2 km SE of Aztec Mt and 3.5 km SSW of Pyramid Mountain
Survey
Not recorded
Climate
Soil climate zone:
Xerous to subxerous, inland mountains
Site temperature profile
Depth (cm)
Soil temp (°C)
Notes
0
-5.6
Near surface
10
-5.6
20
-6.8
40
-6.6
Estimated mean annual temperature:
-27
°C
Frozen ground depth:
22 cm
Frozen type:
Hard ice-cemented
Frozen comment:
22
Geology
Geological setting:
Local rocks are dolerite and sandstone which outcrop on the ridges and in places in the basin to the south of the ridge and on the slopes of Aztec Mountain; the ridge forms a distinct depositional feature and is undoubtedly an old till, probably deposited as a result of early high level ice filling Beacon Valley; the moraine ridge is similar to others seen at high levels in the Taylor and Wright Valleys in that it contains erratics of non local origin, granites and other unidentified crystalline rocks; if the age of moraines on lower surfaces of Beacon Valley are 'old' as prescribed by volcanic ashes (Denton & Sugden etc) then this higher level moraine must be much older
Patterned ground:
Moderately developed nets, 10-15 m in diameter with 40 cm deep PG cracks, not strongly active
Surface weathering or surface features:
Dolerite clasts are strongly stained, mainly subrounded and some partly cavernously weathered; some exfoliation and pitting are present; sandstones have very strong surface oxidation, granite fragments are crumbled and some clasts well oxidised; some salts beneath surface clasts; pavement is well developed,
Soil
Soil parent material:
Dominantly dolerite, sandstone bouldery till with some granite and occasional other rock types, ice cemented;
Surface horizons moist due to recent snow fall and slight thawing, lower horizons have low moisture content, ice-cemented soil with moderately high moisture content; recent snowfall was 7 cm; some water in hollows on surface rocks
Biological activity:
Nil seen
Profile Description
Horizon
Depth
Description
827a
-3 – 0 cm
surface pebbles, granules and sand of predominantly dolerite and sandstone with some granite clasts; mainly subrounded and strongly stained; moist;
827b
0 – 3 cm
brown to dark brown (7.5YR 5/4 - 4/4) bouldery to pebbly sandy gravel; moderately cohesive; diffuse scattered fine salt crystals; rock particles mainly subrounded and strongly stained with some amorphous coatings; indistinct boundary,
827c
3 – 10 cm
strong brown (7.5YR 5/6) bouldery to pebbly sandy gravel; moderately cohesive; salts moderately abundant, mainly diffuse and patchy with some concentrated around stones; rock particles mainly subrounded and strongly stained with some altered; dry; indistinct boundary,
827d
10 – 22 cm
brown to strong brown (7.5YR 5/4 - 5/6) bouldery to pebbly gravel; weakly cohesive to loose; coarser rock particles mainly subangular and weakly to moderately stained but smaller particles more strongly stained; dry; sharp boundary,
827e
22 – 30 cm
yellowish brown (10YR 5/6) very hard ice-cemented frozen ground