EG206 | EG55 | Profile No. 215 | EG71
Geology
Palaeozoic granite and associated metamorphic gniesses.
Landform
Enclosed low hills and valleys. Apart from the slopes adjoining the drainage lines, typical slope gradients are 8-20% with a relief of 30-90 m. The map unit may be subdivided into three components: crest and long gentle slopes, low lying open depressions and steep slopes adjoining drainage lines.
Cleared low hills on granite north of Lake Omeo
Original vegetation
Montane grassy woodland.
Soils
Component 1: Soils on crests and long gentle slopes
The majority of the soils of this unit are texture contrast soils with strongly acidic to moderately acidic surface soils. The surface soils are mostly brown to dark brown weakly structured sandy loams and overlie a bleached subsurface of similar texture. The subsoils, which occur about 30 to 60 cm, are brown to yellowish brown medium clays, often with paler coloured mottling. Rock generally occurs deeper than 1 m. (Sites EG 55, EG 206, Profile No. 215 (Rowe, 1967)). Very occasionally quartz stones occur which tend to accumulate in the surface soil just above the subsoil clay. These are believed to be due to lag deposits from narrow quartz rich dykes which can form in the granite rock.
Quartz stones in the surface soil down-slope from a quartz rich dyke (left hand side of photo).
Component 2: Soils in low lying open depressions
The surface soils are generally very dark grey sandy loams to sandy clay loams overlying dark grey coarsely structured medium to heavy clays. (Site EG116).
Component 3: Soils on steep slopes adjoining drainage lines
On the steep slopes rock outcrops are common. No soil pits were excavated on this component.
Stone layer in cutting on Omeo – Swifts Creek road near Livingston Road | On steep slopes adjoining streams rock outcrops are common Land use All of the area is cleared and used for grazing. |
Location: Omeo south | Geo. Ref. 0557479E 5887924N |
Australian soil classification: Eutrophic, Mottled-Subnatric, Brown SODOSOL | Sodic brown texture contrast soil |
General landscape description: Undulating low hills | |
Geology: Palaeozoic granite | |
Site Description: Convex lower slope, 2 % slope to North | |
Land use: Grazing on annual pasture | |
Native vegetation: Montane grassy woodland | |
Mapping unit: Omeo (Component 1) |
Surface soil | |||
A1 | 0 – 15 cm | Brown (7.5YR4/2); sandy loam; weak medium (10 – 20 mm) polyhedral structure; firm consistence dry; clear change to: | |
A2 | 15 – 32 cm | Pale brown (10YR6/3) conspicuously bleached (10YR8/2d); sandy loam; apedal weak consistence dry; few (2 – 10 %) medium (2 – 6 mm) ferruginous concretions; sharp change to: | |
Subsoil | |||
B21 | 32 – 70 cm | Dark yellowish brown (10YR4/6) diffusely mottled with greyish brown (10YR5/2); medium clay; weak to moderate coarse (20 – 50 mm) prismatic structure; strong consistence dry; diffuse change to: | |
B22 | 70 – 110+ cm | Brown (10YR4/3); medium clay; moderate coarse (20 – 50 mm) lenticular structure; strong consistence dry | |
Key profile features
|
pH | Salinity rating | Sodicity | Dispersion | Slaking | |
Surface soil (A1 horizon) | Strongly acid | Very low | Non sodic | Slight | Slakes partially |
Subsoil (B21 horizon) | Slightly acid | Very low | Non sodic | None | Slakes considerably |
Deeper subsoil (B22 horizon) | Slightly alkaline | Low | Sodic | None | Slakes considerably |
Horizon | Depth cm | Field texture | pH water | pH CaCl2 | EC dS/m | Coarse sand % | Fine sand % | Silt % | Clay % | Field cap. % w/w | Wilt. point % w/w | PAW* water % w/w |
A1 | 0-15 | SL | 5.3 | 4.6 | 0.07 | 22 | 36 | 28 | 7 | 23.3 | 5.2 | 18.1 |
A2 | 15-32 | SL | 5.4 | 4.7 | <0.05 | 22 | 37 | 28 | 8 | 17.7 | 3.5 | 14.2 |
B21 | 32-70 | MC | 6.5 | 5.7 | 0.14 | 15 | 15 | 12 | 54 | 31.0 | 18.8 | 12.2 |
B22 | 70-110 | MC | 7.3 | 6.6 | 0.31 | 6 | 12 | 20 | 60 | 38.8 | 22.2 | 16.6 |
Depth | Org C# | Total N | Free Fe2O3 % w/w | Exch. Al | Exchangeable cations meq/100 g | Ca:Mg | Na % | ||||||
cm | % | % | ppm | Ca | Mg | K | Na | Total | H | CEC | |||
0-15 | 2.1 | 0.15 | <10 | 2.7 | 0.56 | 0.16 | 0.12 | 3.5 | 5.6 | 9.1 | 4.8 | 1 | |
15-32 | 0.59 | <0.05 | <10 | 1.4 | 0.36 | <0.05 | 0.11 | 1.9 | 2.1 | 4.0 | 3.8 | 3 | |
32-70 | 0.55 | 6.3 | 7.4 | 0.26 | 1.3 | 15 | 5.8 | 20.8 | 0.8 | 6 | |||
70-110 | 0.38 |
Location: Upper Livingston Road | Geo. Ref. 0548363E 5884687N |
Australian soil classification: Bleached, Eutrophic, Yellow CHROMOSOL | Yellow texture contrast soil |
General landscape description: Rolling low hills | |
Geology: Ordovician metamorphosed sediments (gneiss) | |
Site Description: Lower slope (unspecified gradient) | |
Land use: Grazing on annual pasture | |
Native vegetation: Montane grassy woodland | |
Mapping unit: Omeo (Component 1) |
Surface soil | |||
A1 | 0 – 10 cm | Dark brown (7.5YR3/2); sandy loam; weak polyhedral structure; clear change to: | |
A21 | 10 – 25 cm | Yellowish brown (10YR5/4) conspicuously bleached dry; loamy sand; massive; gradual change to: | |
A22 | 25 – 45 cm | Light yellowish brown (2.5YR6/4) conspicuously bleached dry; coarse sandy loam; massive; common (10 – 20%) fine gravel (2 – 6 mm); clear change to: | |
Subsoil | |||
B2 | 45 – 85 cm | Yellowish brown (10YR5/4); medium clay; strong coarse prismatic structure parting to angular blocky structure; slight (2 – 10%) fine gravel (2 – 6 mm), with increasing amounts of angular tabular pebbles (20 – 60 mm) becoming larger in size with depth; clear change to: | |
C | 85 cm+ | Decomposing rock |
pH | Salinity rating | Sodicity | Dispersion | Slaking | |
Surface soil (A1 horizon) | Strongly acid | Very low | Non sodic | Slight | Water stable |
Subsurface (A22 horizon) | Moderately acid | Very low | Non sodic | Strong | Slakes partially |
Deeper subsoil (B2 Horizon) | Moderately acid | Very low | Non sodic | Strong | Slakes partially |
Horizon | Depth cm | Field texture | pH water | pH CaCl2 | EC dS/m | Coarse sand % | Fine sand % | Silt % | Clay % | Field cap. % w/w | Wilt. point % w/w | PAW* water % w/w |
A1 | 0-10 | SL | 5.5 | 4.8 | 0.11 | 33 | 35 | 16 | 11 | 20.5 | 7.5 | 13.0 |
A21 | 10-25 | LS | 5.8 | 5.1 | 0.06 | 40 | 36 | 15 | 10 | 14.6 | 3.6 | 11.0 |
A22 | 25-45 | KSL | 5.8 | 5 | 0.05 | 35 | 33 | 13 | 19 | 15.2 | 6.5 | 8.7 |
B2 | 45-85 | MC | 6.0 | 5.1 | 0.07 | 20 | 19 | 12 | 50 | 30.7 | 17.3 | 13.4 |
Depth | Org C# | Total N | Free Fe2O3 % w/w | Exch. Al | Exchangeable cations meq/100 g | Ca:Mg | Na % | ||||||
cm | % | % | ppm | Ca | Mg | K | Na | Total | H | CEC | |||
0-10 | 4.0 | 0.2 | <10 | 2.9 | 1.6 | 0.71 | 0.11 | 5.4 | 9.1 | 14.5 | 1.9 | 1 | |
10-25 | <10 | 1.0 | 0.69 | 0.39 | 0.06 | 2.2 | 3.4 | 5.6 | 1.5 | 1 | |||
25-45 | 15 | 0.98 | 1.6 | 0.35 | 0.09 | 3.1 | 3.7 | 6.8 | 0.7 | 1 | |||
45-85 | 15 | 2.0 | 5.0 | 0.87 | 0.25 | 8.2 | 7.7 | 15.9 | 0.4 | 2 |
Location: Bald Hills Road Omeo south | No Geo. Ref. available |
Australian soil classification: Eutrophic, Subnatric, Yellow SODOSOL | Sodic yellow texture contrast soil |
General landscape description: Undulating low hills | |
Geology: Palaeozoic granite | |
Site Description: None given | |
Land use: Grazing on annual pasture | |
Native vegetation: Montane grassy woodland | |
Mapping unit: Omeo (Component 1) |
Horizon | Depth cm | Field texture | pH water | pH CaCl2 | EC dS/m | Coarse sand % | Fine sand % | Silt % | Clay % | Field cap. % w/w | Wilt. Point % w/w | PAW* water % w/w |
A1 | 0-8 | L | 5.6 | 0.05 | 27 | 26 | 24 | 20 | ||||
A2 | 15-30 | LS | 6.0 | <0.05 | 39 | 36 | 16 | 7 | ||||
B21 | 30-60 | C | 6.5 | 0.08 | 16 | 15 | 7 | 61 | ||||
B22 | 90-120 | C | 8.4 | 0.16 | 41 | 31 | 12 | 17 |
Depth | Org C# | Total N | Free Fe2O3 % w/w | Exch. Al | Exchangeable cations meq/100 g | Ca:Mg | Na % | ||||||
cm | % | % | ppm | Ca | Mg | K | Na | Total | H | CEC | |||
0-8 | 1.7 | 0.15 | 1.0 | 4.6 | 1.7 | 0.4 | 0.1 | 6.8 | 7.4 | 14.2 | 2.7 | 1 | |
15-30 | 0.2 | 0.02 | 0.8 | 1.3 | 0.6 | 0.1 | 0.05 | 2.1 | 2.9 | 5.0 | 2.2 | 1 | |
30-60 | 2.9 | 3.7 | 12.4 | 0.3 | 1.9 | 18.3 | 20.5 | 28.8 | 0.3 | 7 | |||
90-120 | 1.8 | 3.3 | 9.5 | 1.9 | 2.8 | 15.7 | - | 15.4 | 0.4 | 18 |
Location: Omeo, Barbers Lane | Geo. Ref. 0555912E 5892285N |
Australian soil classification: Yellow SODOSOL | Sodic yellow texture contrast soil |
General landscape description: Undulating low hills | |
Geology: Palaeozoic granite | |
Site Description: Hill-slope, gradient unspecified | |
Land use: Grazing on annual pasture | |
Native vegetation: Grassy woodland | |
Mapping unit: Omeo (Component 1) |
Surface soil | |||
A1 | 0 – 25/30 cm | Very dark greyish brown (10YR3/2); sandy loam (light and high in organic matter); weak polyhedral structure; common (10 – 20%) fine (2 – 6 mm) gravel; clear wavy change to: | |
A2 | 25/30 – 50/55 cm | Very pale brown (10YR7/3) conspicuously bleached (10YR8/2d); loamy sand; massive; strong consistence dry; slight (2 – 10%) fine (2 – 6 mm) gravel; clear wavy change to: | |
Subsoil | |||
B21 | 50/55 – 100 cm | Yellowish brown (10YR5/4); medium heavy clay; coarse prismatic structure parting to angular blocky structure; strong consistence dry; slight (2 – 10%) fine (2 – 6 mm) gravel. |