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Soils on Basaltic Terrain

Qbb - Steep-sided Valleys with Duplex Soil on Quaternary Basalt | Qbbd - Steep-sided Valley with Duplex Soils on Quaternary Basalt. Drier than Qbb | Qbc - Plains with Clay Soils on Quaternary Basalt | Qbcd - Plains with Clay Soils on Quaternary Basalt. Drier than Qbc | Qbf - Plain with Clay Soil and Duplex Soils and Quaternary Basalt | Qbg - Plains with Duplex Soils on Quaternary Basalt | Qbgd - Plains with Duplex Soil on Quaternary Basalt. Drier than Qbg | Qbgs - Stony Plains with Duplex Soils on Quaternary Basalt | Qbgw - Plains with Duplex Soils with a Sandy Horizon on Quaternary Basalt | Qbs - Stony Rises with Gradational Soils on Quaternary Basalt | Qbsd - Stony Rises with Gradational Soils on Quaternary Basalt. Drier than Qbs | Tbd - Slopes with Clay Soil on Tertiary Basalt

Qbg - Plains with Duplex Soils on Quaternary Basalt

Plains with Duplex Soils on Quaternary Basalt - QbgFlat to gently undulating basaltic plains with poorly drained sodic duplex soils predominating. This extensive plain occurs in the north around Meredith and with a total area of 48 km2, represents 6.8% of the Shire.

Qbg is similar to Qbgd but the climate is wetter. (The land is used mainly for grazing, with some cropping). Extensive flat or low lying areas are particularly poorly drained and are subject to seasonally high watertables and some surface ponding.

SOILS
The most common soil occurs in Component 1. The heavy clay subsoil is slowly permeable, highly expansive and may be 1 to 4 m thick. While the Factual Key classifies the soil on the relatively thin B1 horizon which is dark, the overall impression from a deep excavation is of a yellowish grey duplex soil.

Mottled, Dark Grey Sodic Duplex Soils - Coarse Structure

Factual Key: Dd 2.43/CL, 10-60 cm/basalt, 30-400 cm

Horizon
Depth (cm)
Description
A1
0-20
Brownish black (10YR 3/2) when moist; clay loam; weak subangular blocky 7 mm; consistence when slightly moist is firm; pH 5.4; sharp boundary.
A2
20-50
Greyish yellow brown (10YR 5/2) when moist; clay loam; apedal and massive; consistence when slightly moist is firm; some buckshot gravel increasing to 60-80% at the A2/B21 interface - average size 4 mm; pH 6.0; sharp boundary.
B21
50-100
Brownish black (10YR 3/3) when moist; heavy clay with yellow mottling with a moderate sub-angular blocky 50 mm breaking down to a strong angular blocky 2 mm; consistence when slightly moist is extremely firm; pH 7.5; diffuse boundary.
B22
100-200+
Greyish yellow brown (10YR 4/2) when moist; heavy clay; strong subangular blocky 80 mm breaking down to a strong angular blocky 2 mm; consistence when slightly moist is extremely firm; may contain basalt floaters; pH 8.0.

COMPONENT
Proportion %
1
95
2
3
3
2
CLIMATE
Rainfall(av.) mm
Annual 610 - 660
Temperature(av.) C
Annual 12
GEOLOGY
Age, rock
Pleistocene, basalt
TOPOGRAPHY
Landscape
Extensive, slightly dissected plains in the north of the Shire
Elevation (range) m
240 - 365
Local relief (av.) m
2
Drainage pattern
Dendritic
Drainage density km/km2
0.5
Land form
Plain
Position on land form
Long gentle upper slopes
Depression
Stony rise
Slope (range) %, slope shape
1-3 ; Straight
1-2 ; Straight
2-5 ; Convex
NATIVE VEGETATION
Structure
Woodland (?)
Dominant species
E. ovata, E. viminalis, E, rubida, E. obliqua
E. viminalis, E. rubida,
E. obliqua, E. ovata
SOIL
Parent material
In-situ weathered rock
Alluvium
In-situ weathered rock
Description
Mottled dark-grey sodic duplex soils coarse structure
Black clay soils, uniform texture, coarse structure
Red shallow stony gradational soils
Factual key
Dd 2.43
Ug 5.1
Gn 3.11
Surface texture
Clay loam
Clay
Clay loam
Permeability
Low
Low
High
Depth (range) m
1.0
4.0
0.2 - 0.5
LAND USE
Grazing, occasional cropping (cereal)
Grazing
SOIL DETERIORATION
Critical land features
Hard setting surfaces, slowly .permeable subsoils
Clay soils in drainage lines Seasonal high watertables
Slopes
Processes
Overland flow, periodic waterlogging
Overland flow, periodic waterlogging
Overland flow, leaching
Forms
Surface compaction, minor sheet erosion
Surface compaction, minor rill erosion
Sheet erosion, nutrient decline


Qbgd - Plains with Duplex Soil on Quaternary Basalt. Drier than Qbg

Plains with Duplex Soils on Quaternary Basalt.  Drier than Qbg - QbgdFlat to gently undulating basalt plains scattered throughout the southern two-thirds of the Shire. Total area is 29 km2, representing 4.1% of the Shire.

Qbgd is similar to Qbg except that the climate is drier and River red gum (E. camaldulensis) is more common.

The land is particularly poorly drained in the flatter areas, having seasonally high watertables and areas of surface ponding. It is used for grazing and cereal cropping.

SOILS
The major soil is that of Component 1. The heavy clay of the subsoil is impermeable, highly expansive and may be 0.5 to 3 m thick. While the Factual Key classifies the soil on the relatively thin B1 horizon which is dark, the overall impression from observation of a deep excavation is of the yellowish-grey clay of the duplex soil.

Mottled Dark Grey Sodic Duplex Soils - Coarse Structure

Factual Key: Dd 2.43/CL, 10-60 cm/basalt, 30-400 cm

Horizon
Depth (cm)
Description
A1
0-20
Brownish black (10YR 3/2) when moist; clay loam; weak sub-angular blocky 7 mm; consistence when slightly moist is firm; pH 5.4; sharp
boundary.
A2
20-50
Greyish yellow brown (10YR 4/2) when moist; clay loam; apedal and massive; consistence when slightly moist is firm; some buckshot gravel throughout the A2 increasing to 50-70% buckshot average size 4 mm at the A2/B1 interface; pH 6.0; sharp boundary.
B21
50-80
Brownish black (10YR 3/1) when moist; heavy clay with yellow mottling with a moderate subangular blocky 50 mm breaking to a strong blocky 2 mm; consistence when slightly moist is extremely firm; pH 7.5; diffuse boundary.
B22
80-150+
Greyish yellow brown (10YR 4/2) when moist; heavy clay; strong sub-angular blocky 80 mm breaking down to a strong angular blocky 2 mm; consistence when slightly moist is' extremely firm; may contain basalt floaters; pH 8.0.

COMPONENT
Proportion %
1
95
2
3
3
2
CLIMATE
Rainfall(av.) mm
Annual 530 - 610
Temperature(av.) C
Annual 12 - 13
GEOLOGY
Age, rock
Pleistocene, basalt
TOPOGRAPHY
Landscape
Extensive, slightly dissected plains
Elevation (range) m
61 - 265
Local relief (av.) m
8
Drainage pattern
Dendritic
Drainage density km/km2
0.7
Land form
-
Position on land form
Long gentle upper slopes
Depression
Stony rise
Slope (range) %, slope shape
1-3 ; Straight
1-2 ; Straight
2-5 ; Convex
NATIVE VEGETATION
Structure
Woodland ?
Dominant species
E. camaldulensis, E. leucoxylon,
E. melliodora
E. camaldulensis
SOIL
Parent material
In-situ weathered rock
Alluvium
In-situ weathered rock
Description
Mottled dark grey sodic duplex soils coarse structure
Black clay soils, uniform texture coarse structure
Red shallow stony gradational soils
Factual key
Bd 2.43
Ug 5.1
Gn 3
Surface texture
Clay loam
Clay
Clay loam
Permeability
Low
Low
High
Depth (range) m
1.0 - 3.0
0.2 - 0.5
LAND USE
Grazing, cropping (cereal)
Grazing
SOIL DETERIORATION
Critical land features
Hard setting surfaces, slowly permeable subsoils
Seasonal high watertables, low lying areas
Gradient
Processes
Overland flow, periodic waterlogging
Overland flow, periodic waterlogging
Overland flow
Forms
Minor sheet erosion, surface compaction
Billing, minor gully erosion in disturbed soil. Salting
Minor sheet erosion

Qbgw - Stony Plains with Duplex Soils on Quaternary Basalt

Plains with Duplex Soils with a Sandy A Horizon on Quaternary Basalt - QbgwFlat to gently undulating basalt plains similar to Qbgd but with sandy topsoils. Several large areas occur in the southern half of the Shire. The total area is 27.0 km2, representing 3.9% of the study area.

The sand in the topsoil does not originate from the basalt parent material, but is a wash and, in some cases a wind-blown addition. The subsoil is a heavy, sodic clay of low permeability and high shrink-swell potential (cracks on drying), often containing basalt floaters. It can be a problem for building foundations. The land has seasonally poor drainage - especially on the flatter areas.

The main land use is grazing, with some cereal cropping.

SOILS
The most common soil type occurs on Component 1. The amount of sand in the A1 and A2 horizons vary.

Mottled Dark-grey Sodic Duplex Soils - Coarse Structure

Factual Key: Db 2.43 (Some Dd 2.43)/LS-SCL, 20-50 cm/basalt 100-200 cm

Horizon
Depth (cm)
Description
A1
0-15
Greyish brown (7.5YR 4/2) when moist, loamy sand; apedal and massive; consistence when moist is friable; pH 4.5; clear boundary.
A2
15-40
Greyish yellow brown (101R 5/2) when moist, with brown rootline mottles; loamy sand; apedal single-grained; consistence when moist is loose; pH 4.0; abrupt boundary.
B1
40-60
Dark brown (10YR 3/3) when moist, with orange mottles; medium clay; moderate sub-angular blocky 30 mm; consistence when wet is plastic; pH (.0; gradual boundary.
B2
40-100+
Dark brown (10YR 3/3) when moist; with yellow mottles; heavy clay; moderate angular blocky 80 mm; consistence when moist - very plastic; when dry - very hard; may contain basalt floaters; pH 9.0.

COMPONENT
Proportion %
1
95
2
3
3
2
CLIMATE
Rainfall(av.) mm
Annual 500 - 580
Temperature(av.) C
Annual 13
GEOLOGY
Age, rock
Pleistocene, basalt
TOPOGRAPHY
Landscape
Slightly dissected plains throughout the southern part of the Shire
Elevation (range) m
61 - 249
Local relief (av.) m
14
Drainage pattern
Dendritic
Drainage density km/km2
0.6
Land form
Long gentle slopes
Drainage line
Stony rise
Position on land form
Slopes
Depression
-
Slope (range) %, slope shape
1-3 ; Straight
1-2 ; Straight
2-5 ; Convex
NATIVE VEGETATION
Structure
Woodland (?)
Dominant species
E. leucoxylon
SOIL
Parent material
In-situ weathered rock
Alluvium
In-situ weathered rock
Description
Mottled dark grey sodic duplex soils, coarse structure
Black clay soils, uniform texture, coarse structure
Red shallow stony gradational soils
Factual key
Db 2.33 and Db 2.43
Ug 5.1
Gn 3
Surface texture
Sandy loam
Clay
Clay loam
Permeability
Moderate-low
Low
High
Depth (range) m
1.0 - 3.0
0.2 - 0.5
LAND USE
Grazing, occasional cropping (cereal)
Grazing
SOIL DETERIORATION
Critical land features
Hard setting surfaces, slowly permeable subsoils
Clay soils in drainage line
Slopes
Processes
Overland flow, periodic waterlogging
Overland flow, periodic waterlogging
Overland flow, leaching
Forms
Surface compaction, sheet erosion
Surface compaction, minor rill erosion
Sheet erosion, nutrient decline


Qbb - Steep-sided Valley with Duplex Soil on Quaternary Basalt

Steep-sided Valley with Duplex Soils on Quaternary - QbbScarps and alluvial flats in the north of the Shire associated with creeks that have out into the basalt plain. The unit totals 7.7 km2, representing 1.1% of the Shire.

The size of the alluvial flats is variable throughout the unit; where they are large enough, they have been mapped as a separate unit, Qya. The slopes of the scarps vary in steepness, but are generally rocky and have shallow stony soils: There may be some risk of landslips when unconsolidated sediments below the basalt are exposed by the scarp. Also, where the dark clayey soils are deep, slumping may occur particularly in batters. The main land use is grazing.

This unit is similar to Qbbd but the climate here is wetter.

SOILS
The most common soil, an example. of which is described below, occurs on the slopes (Component 1). It is usually a brown duplex but there may be areas of a red gradational soils or black clays where the soil is deeper.

Shallow Brown Duplex Soils

Factual Key: Db 1.11/CL, 20-40 cm/basalt, 10-45 cm

Horizon
Depth (cm)
Description
A
0-20
Brownish black (7.5YR 3/2) when moist; clay loam; weak subangular blocky 5 mm; consistence when dry is slightly hard; 20% stones of parent material (4-30 cm average diameter); pH 6.0; abrupt boundary.
B
20-30
Dark brown (10YR 3/3) when moist; medium clay; moderate to strong angular blocky 4 mm; consistence when dry is hard; 00% stones of parent material (10-50 cm average diameter) and 5% of buckshot; pH 6.0; abrupt boundary.
R
30+
Weathering basalt.

COMPONENT
Proportion %
1
60
2
40
CLIMATE
Rainfall(av.) mm
Annual 610 - 660
Temperature(av.) C
Annual 12
GEOLOGY
Age, rock
Pleistocene basalt
TOPOGRAPHY
Landscape
Scarps beside main creeks in the north of the Shire usually including the creek alluvium
Elevation (range) m
200 - 350
Local relief (av.) m
15
Drainage pattern
-
-
Drainage density km/km2
-
-
Land form
Steep valley side with local rock outcrop
Creek bed and flood plain
Position on land form
-
-
Slope (range) %, slope shape
10-35 ; Convex
1-5 ; Straight
NATIVE VEGETATION
Structure
Open forest
Dominant species
E. viminalis, E. ovata
SOIL
Parent material
In-situ weathered rock
Unconsolidated sedimentary and in-situ weathered rock
Description
Shallow brown duplex or gradational soils
Black clay soils, uniform texture, coarse structure
Factual key
Db 1.11
Ug 5.1
Surface texture
Clay loam
Clay
Permeability
Moderate
Low
Depth (range) m
0.3 - 1.2
1.0 - 2.0
LAND USE
Grazing
SOIL DETERIORATION
Critical land features
Slope, hard setting surfaces
Seasonal high watertables Poorly drained site, low permeability
Processes
Overland flow
Overland flow, periodic waterlogging
Forms
Minor sheet and rill erosion, low landslip hazard
Streambank erosion, surface compaction


Qbsd - Stony Rises with Gradational Soils on Quaternary Basalt drier than Qbs

Stony Rises with Gradational Soils on Quaternary Basalt drier than Qbs - QbsdLow stony rises on basalt. There are several small patches in the south of the Shire but only one extensive area, which is to the west of Lethbridge. The total area of 7.3 km2 represents 1.0% of the Shire.

The small areas of Qbsd occur as stony rises on the basalt plains or as isolated remnants of basalt in other units. The large area west of Lethbridge has a slightly higher elevation than the surrounding basalt and Tga units. The degree of surface stoniness varies considerably and many areas have been cleared to allow for grazing and some cropping. Rock piles and stone fences are common around these areas.

Irrespective of surface stoniness, all areas have shallow black uniform soils, usually with large quantities of rock, overlying hard bedrock. The soils are not very permeable but drainage is better than in other gently sloping basalt units because there is surface runoff to surrounding lower land.

SOILS
The most common soil is found on both Components 1 and 2, and is usually a Ug 5.12, although others occasionally do occur.

Stony Black, Clay Soils, Uniform Texture, Coarse Structure

Factual Key: Ug 5.12/LC-MC; 10-20 cm/basalt, 50-100 cm

Horizon
Depth (cm)
Description
A1
0-10
Black (10YR 2/1) when moist; light medium clay; strong angular blocky 10 mm; consistence when moist is firm; 5-70% surface stones; pH 7.0; clear boundary.
B
10-60
Brown black (10YR 3/1) when moist; heavy clay; strong angular blocky 3 mm: consistence when wet, very plastic; 10-50% basalt stones and boulders; pH 8.5.
R
60+
Basalt rock.

COMPONENT
Proportion %
1
90
2
10
CLIMATE
Rainfall(av.) mm
Annual 500 - 600
Temperature(av.) C
Annual 12
GEOLOGY
Age, rock
Pleistocene basalt
TOPOGRAPHY
Landscape
Stony rise area west of Lethbridge
Elevation (range) m
110 - 235
Local relief (av.) m
10
Drainage pattern
Dendritic
Drainage density km/km2
0.2
Land form
Stony rise
Drainage line
Position on land form
Slopes
Depression
Slope (range) %, slope shape
1-5 ; Convex
1-2 ; Straight
NATIVE VEGETATION
Structure
Woodland ?
Dominant species
E. camaldulensis
SOIL
Parent material
In-situ weathered rock
In-situ weathered rock with some alluvium
Description
Stony black clay soil, uniform texture, coarse structure
Black clay soil, uniform texture, coarse structure
Factual key
Ug 5.12 or Ug 5.14
Ug 5.1
Surface texture
Clay
Clay
Permeability
Low
Low Low
Depth (range) m
0.5 -.1.0
1.0 - 2.0
LAND USE
Grazing
SOIL DETERIORATION
Critical land features
Slope gradient
Slope gradient
Processes
Overland flow
Overland flow
Forms
Minor sheet erosion, nutrient decline
Minor rill erosion


Qbc - Plains with Clay Soils on Quaternary Basalt

Plains with Clay Soils on Quaternary Basalt - QbcSmall areas of black, cracking, clay soils on gently undulating basalt plains in the northern section of the Shire. The unit covers only 0.3 km2 or 0.04% of the survey area - one of the smallest units.

It is similar to Qbcd, but the climate is wetter. The land-use is mainly cereal cropping and grazing. The heavy clay soil retains moisture well but is difficult to work into a fine seedbed except at optimum moisture content.

The unit generally has a low erosion hazard, and could be used more intensively. The clay, however, is highly expansive and has a high plasticity index - special foundations for constructions are required.

SOILS
The soil is fairly homogeneous throughout this unit.

Black Clay Soils, Uniform Texture - Self Mulching

Factual Key: Ug 5.14/LC-MC, 10-30 cm/basalt, 80-160 cm

Horizon
Depth (cm)
Description
A
0-20
Black (10YR 2/1) when moist; medium clay; strong angular blocky 15 mm; consistence when moist is very firm; pH 7.0; clear boundary.
B
20-80
Brownish black (10YR 3/1) when moist; heavy clay; strong angular blocky 2 mm; consistence when wet, very plastic; occasional basalt stones and boulders; pH 8.5; diffuse boundary.
C
80-120
Grey (2.5YR 4/0) when moist; heavy clay; strong angular blocky 1 mm; consistence when wet is very plastic; occasional basalt stones and boulders; pH 8.0.
R
120+
Basalt rock at variable depth

COMPONENT
Proportion %
1
100
CLIMATE
Rainfall(av.) mm
Annual 650 - 685
Temperature(av.) C
Annual 12
GEOLOGY
Age, rock
Pleistocene, basalt
TOPOGRAPHY
Landscape
Slightly dissected plains in the north of the Shire
Elevation (range) m
228 - 267
Local relief (av.) m
5
Drainage pattern
Dendritic
Drainage density km/km2
1.7
Land form
Plain
Position on land form
-
Slope (range) %, slope shape
2-10 ; Convex
NATIVE VEGETATION
Structure
(?)
Dominant species
SOIL
Parent material
In-situ weathered rock
Description
Black clay soils. uniform texture, coarse structure - self mulching
Factual key
Ug 5.14
Surface texture
Heavy clay
Permeability
Moderate
Depth (range) m
0.8 - 1.6
LAND USE
Cropping (cereal), occasional grazing
SOIL DETERIORATION
Critical land features
Slope
Processes
Overland flow
Forms
Minor sheet erosion


Qbbd - Steep-sided Valleys with Duplex Soil on Quaternary Basalt. Drier than Qbb

Steep-sided Valley with Duplex Soils on Quaternary Basalt drier than Qbb - QbbdModerate to very steep scarps caused by creeks cutting into the basalt plain. Includes the alluvium of the creek unless these areas are sufficiently large to be mapped as a separate unit. There are about a dozen occurrences of the unit throughout the southern half of the Shire, including some sections along the stony lip of the Moorabool River near She Oaks. The total of 8.2 km2, represents 1.2% of the Shire. It is similar to Qbb in the north but the climate of Qbbd is drier.

The slopes are usually stony. There is generally not much erosion evident despite the steep slopes because a protective grassland cover develops readily on the fertile, moderately permeable soils. Gullying will occur rapidly if the soil is exposed to concentrated runoff.

Where the soils are deeper or the basalt overlies unconsolidated material, landslips may occur. Grazing and recreation are the main land uses.

SOILS
The soil description below is representative of Component 1.

Shallow Brown Duplex Soils

Factual Key: Db 1.11/CL, 20-40 cm/basalt, 10-45 cm

Horizon
Depth (cm)
Description
A
0-20
Brownish black (7.5YR 3/2) when moist; clay loam; weak subangular blocky 5 mm; consistence when dry is slightly hard; 20% stones of parent material (8 cm average size); pH 6.0; abrupt boundary.
B
20-30
Dark brown (10YR 3/3) when moist; medium clay; moderate to strong angular blocky 4 mm; consistence when dry is hard; 80% stones of parent material (30 cm average size) and 5% of buckshot; pH 6.0; abrupt boundary.
R
30+
Weathering basalt.

COMPONENT
Proportion %
1
70
2
30
CLIMATE
Rainfall(av.) mm
Annual 510 - 580
Temperature(av.) C
Annual 13
GEOLOGY
Age, rock
Pleistocene, basalt
TOPOGRAPHY
Landscape
Scarp beside main creek including the river channel in places
Elevation (range) m
30 - 198
Local relief (av.) m
38
Drainage pattern
Dendritic
Drainage density km/km2
1.2
Land form
Scarp with local rock outcrop
Creek bed
Position on land form
Slope
Flood plain
Slope (range) %, slope shape
10-30 ; Convex
1-3 ; Straight
NATIVE VEGETATION
Structure
Woodland (?)
Dominant species
E. camaldulensis
SOIL
Parent material
In-situ weathered rock
Unconsolidated sedimentary and in-situ weathered rock
Description
Shallow brown duplex or gradational soils
Black clay soils, uniform texture, coarse structure
Factual key
Surface texture
Clay loam
Clay
Permeability
High
Low
Depth (range) m
0.5 - 1.5
1.0 - 2.5
LAND USE
Grazing
SOIL DETERIORATION
Critical land features
Steep slope, hard setting surfaces
Poorly drained site, low permeability
Processes
Overland flow, sub surface flow
Overland flow, periodic waterlogging
Forms
Minor sheet and rill erosion, low landslip hazard
Streambank erosion, surface compaction


Tbd - Slopes with Clay Soils on Tertiary Basalt

Slopes with Clay soils on Tertiary Basalt - TbdIsolated crests and slopes near Maude, with moderate to gentle gradients, on Tertiary basalt (older, well weathered basalt). The total area of 1.3 km2, amounts to (only) 0.2% of the Shire.

The black clayey soils, being fertile and having good water holding capacity, are suited to the common uses of cropping and market gardening. However, they do require optimum moisture for seedbed preparation and, once cultivated, deep rilling can occur very rapidly. Under grazing, those soils grow good pasture and, being well protected, are quite stable.

SOILS
The most common soil type (described below) is a uniform, black, cracking clay. There are, however, odd areas of chocolate or red-brown gradational soils.

Dark Uniform Clay Soils

Factual Key: Ug 5.1 / LC-MC, 10-70 cm/older basalt, 10-80 cm.

Horizon
Depth (cm)
Description
A11
0-20
Brownish black (7.5YR 3/2) when moist; light medium clay; moderate subangular blocky, 5mm; consistence when moist is friable; pH 8.0.
A12
20-50
Brownish black (7.5YR 3/2) when moist; light medium clay; strong subangular blocky; consistence when moist is friable1 pH 8.5.
C
50+
Rotting basalt (greenish grey) with lime.

COMPONENT
Proportion %
1
50
2
45
3
5
CLIMATE
Rainfall(av.) mm
Annual 560 - 600
Temperature(av.) C
Annual 12
GEOLOGY
Age, rock
Tertiary basalt
TOPOGRAPHY
Landscape
Isolated occurrences of gentle to moderate slopes near Maude
Elevation (range) m
170 - 190
Local relief (av.) m
15
Drainage pattern
Dendritic
Drainage density km/km2
1
Land form
Crest
Slopes
Drainage line
Position on land form
Highest
Medium
Lowest
Slope (range) %, slope shape
1-5 ; Convex
5-15 ; Convex-Straight
1-3 ; Concave
NATIVE VEGETATION
Structure
Woodland ?
Dominant species
E. leucoxylon
SOIL
Parent material
In-situ weathered rock
Description
Dark uniform clays and sodic chocolate gradational soils
Dark uniform clays and sodic chocolate gradational soils
Yellow mottled dark sodic duplex soils, coarse structure
Factual key
Ug 5.1 - Gn 3.12
Ug 5.1 - Gn 3.12
Dd 2.43
Surface texture
Clay - clay loam
Clay - clay loam
Clay loam
Permeability
Moderate
Moderate
Low
Depth (range) m
0.5 - 1.0
0.3 - 0.8
1 - 1.5
LAND USE
Cropping - grazing
Grazing
SOIL DETERIORATION
Critical land features
Slope gradient, soil permeability
Slope gradient, soil permeability
Seasonal high watertable
Soil permeability, sodic soil, position on landscape
Processes
Overland flow
Overland flow
Overland flow, period waterlogging
Forms
Moderate sheet erosion when fallowed
Moderate sheet erosion
Surface compaction


Qbf - Plain with Clay Soil and duplex Soils and Quaternary Basalt

Plain with Clay Soils and Duplex Soils and Quaternary Basalt - QbfExtensive flat to gently undulating plains located in the centre of the Shire, along the Midland Highway. Having a total area of 46 km2, it occupies 6.6% of the Shire. Black cracking clays, although sporadic in occurrence, are more common than in Qbgd.

Their occurrence may be related to the depth of bedrock. Cropping and grazing are the main uses, with the black cracking clays favoured for cropping.

SOILS
The soil description for Component 2 (the black uniform clay) is the same as for Map Unit Qbcd. The soil description below refers to Component 1.

Mottled, Dark Sodic Duplex Soils - Coarse Structure

Factual Key: Dd 2.43/CL, 10-60 cm/basalt, 30-400 cm

Horizon
Depth (cm)
Description
A1
0-20
Brownish black (10YR 3/2) when moist; clay loam; weak subangular blocky 7 mm; consistence when slightly moist is firm; pH 6.0; sharp boundary.
A2
20-50
Greyish yellow brown (10YR 5/2) when moist; clay loam; apedal and massive; consistence when slightly moist is firm; buckshot gravel increases to 40-70% at the A2/B21 interface; pH 6.0; sharp boundary.
B21
50-110
Brownish black (10YR 3/1) when moist; heavy clay with yellow mottling with a moderate subangular blocky 50 mm breaking down to a strong angular blocky 2 mm; consistence when slightly moist is extremely firm; pH 7.5; diffuse boundary.
B22
110+
Greyish yellow brown (10YR 4/2) when moist; heavy clay; strong subangular blocky 80 mm breaking down to a strong angular blocky 2 mm; consistence when slightly moist is extremely firm; pH 8.0

COMPONENT
Proportion %
1
50
2
40
3
10
CLIMATE
Rainfall(av.) mm
Annual 510 - 630
Temperature(av.) C
Annual 13
GEOLOGY
Age, rock
Pleistocene, basalt
TOPOGRAPHY
Landscape
Plain in the centre of Survey Area along the Midland Highway
Elevation (range) m
60 - 260
Local relief (av.) m
2
Drainage pattern
Dendritic
Drainage density km/km2
0.4
Land form
Plain
Position on land form
Plain
Depression lines
Slope (range) %, slope shape
1-3 ; Straight
1-2 ; Concave
NATIVE VEGETATION
Structure
Woodland (?)
Dominant species
E. camaldulensis, E. leucoxylon, E. melliodora
SOIL
Parent material
In-situ weathered rock
Alluvium mainly from basalt
Description
Mottled dark sodic duplex soils, coarse structure
Black clay soils, uniform texture, coarse structure
Black cracking clays, coarse structure
Factual key
Dd 2.43
Ug 5.1
Ug 5.1
Surface texture
Clay loam
Light to medium clay
Medium clay
Permeability
Very low
Very low
Very low
Depth (range) m
1.0 - 2.0
0.5 - 1.0
1.5 - 2.5
LAND USE
Cropping and grazing
Grazing
SOIL DETERIORATION
Critical land features
Hard setting surfaces
Processes
Overland flow
Forms
Minor sheet erosion


Qbs - Stony Rises with Gradational Soils on Quaternary Basalt

Stony Rises with Gradational Soils on Quaternary Basalt - QbsStony rises on the basalt plains in the north of the Shire. There are only a few localities large enough to be mapped separately at this scale; smaller stony areas elsewhere have been identified by using the symbol “st”.

The total area of 0.3 km2 represents only 0.04% of the total study area. The soil is relatively fertile but the surface basalt stones and boulders generally limit its use to grazing.

SOILS
The soils of this unit are generally very shallow (Um). When soil fills deep crevices in the rock, a Gn (as described) or a Db soil may develop. In extreme cases, a grey heavy clay (in the B22 horizon) may be found.

Red Shallow Stony Gradational Soils

Factual Key: Gn 3.11/L-LC, 5-40 cm/basalt, 5-70 cm.

Horizon
Depth (cm)
Description
A
0-15
Brownish black (5YR 3/2); when moist; gravelly loam; weak subangular blocky 5 mm; consistence when moist is friable; 5% small stones (basalt); pH 5.5; diffuse boundary.
B
15+
Dark reddish brown (5YR 3/4) when moist; clay loam to light clay; strong angular blocky 1 mm; consistence when moist is friable; 40-60% stones (basalt); pH 6.0.
In many instances the B horizon is only present where the soil is deep in crevices in the basalt.

COMPONENT
Proportion %
1
100
CLIMATE
Rainfall(av.) mm
Annual 610 - 660
Temperature(av.) C
Annual 12
GEOLOGY
Age, rock
Pleistocene basalt
TOPOGRAPHY
Landscape
Scattered stony areas in the north of the Shire
Elevation (range) m
270 - 340
Local relief (av.) m
1
Drainage pattern
-
Drainage density km/km2
-
Land form
Stony areas
Position on land form
-
Slope (range) %, slope shape
1-4 ; concave scarps, straight tops
NATIVE VEGETATION
Structure
Woodland ?
Dominant species
E. viminalis
SOIL
Parent material
In-situ weathered rock
Description
Red shallow stony gradational soils
Factual key
Gn 3.12
Surface texture
Clay loam
Permeability
High
Depth (range) m
0.1 - 1
LAND USE
Grazing
SOIL DETERIORATION
Critical land features
Slope, shallow permeable soil
Processes
Overland flow; leaching
Forms
Low sheet erosion, nutrient decline


Qbcd - Plains with Clay Soils on Quaternary Basalt. Drier than Qbc

Plains with Clay Soils on Quaternary Basalt.  Drier than Qbd - QbcdGently sloping areas of black uniform, self-mulching clays on basalt. There are four areas (near She Oaks) totalling 1.1 km2 and comprising 0.1% of the Shire. This unit supports similar land uses to Qbc; however, the climate here is drier. The black soils are quite fertile and are often used for onion growing and other cropping.
Sheet erosion of fallow land can occur. During the summer, deep cracks appear as the clay dries out and shrinks; the magnitude of this shrink-swell property can be a problem for foundation construction.

SOILS
As there is only one component, the soil description below represents the whole unit.

Black Clay Soils, Uniform Texture - Self-Mulching

Factual Key: Ug 5.14/LC-MC, 10-30 cm/basalt, 80-160 cm

Horizon
Depth (cm)
Description
A
0-20
Black (10YR 2/1) when moist; medium clay; strong angular blocky 15 mm; consistence when moist is firm; pH 7.0; clear boundary.
B
20-80
Brownish black (10YR 3/1) when moist; heavy clay; strong angular blocky 2 mm; consistence when wet, very plastic; occasional basalt stones and boulders; pH 8.5; diffuse boundary.
C
80-120
Grey (2.5YR 4/0) when moist; heavy clay; strong angular blocky 1 mm; consistence when wet is very plastic; occasional basalt stones and boulders; pH 8.0.
R
120+
Basalt rock.

COMPONENT
Proportion %
1
100
CLIMATE
Rainfall(av.) mm
Annual 610 - 630
Temperature(av.) C
Annual 2
GEOLOGY
Age, rock
Pleistocene, basalt
TOPOGRAPHY
Landscape
Slightly dissected plains
Elevation (range) m
185 - 251
Local relief (av.) m
3
Drainage pattern
Dendritic
Drainage density km/km2
1.7
Land form
Plain
Position on land form
-
Slope (range) %, slope shape
1-4; Convex
NATIVE VEGETATION
Structure
(?)
Dominant species
SOIL
Parent material
In-situ weathered rook
Description
Black clay soils, uniform texture, coarse structure - self mulching
Factual key
Ug 5.14
Surface texture
Heavy clay
Permeability
Moderate
Depth (range) m
0.8 - 1.5
LAND USE
Market garden (onions), cropping (cereal), occasional grazing
SOIL DETERIORATION
Critical land features
Slope
Processes
Overland flow
Forms
Minor sheet erosion


Qbbd - Steep-sided valley with Duplex Soils on Quaternary Basalt

Steep-sided Valley with Duplex Soils on Quaternary Basalt drier than Qbb - QbbdModerate to very steep scarps caused by creeks cutting into the basalt plain. Includes the alluvium of the creek unless these areas are sufficiently large to be mapped as a separate unit. There are about a dozen occurrences of the unit throughout the southern half of the Shire, including some sections along the stony lip of the Moorabool River near She Oaks.

The total of 8.2 km2, represents 1.2% of the Shire. It is similar to Qbb in the north but the climate of Qbbd is drier.

The slopes are usually stony. There is generally not much erosion evident despite the steep slopes because a protective grassland cover develops readily on the fertile, moderately permeable soils. Gullying will occur rapidly if the soil is exposed to concentrated runoff. Where the soils are deeper or the basalt overlies unconsolidated material, landslips may occur. Grazing and recreation are the main land uses.

SOILS
The soil description below is representative of Component 1.

Shallow Brown Duplex Soils

Factual Key: Db 1.11/CL, 20-40 cm/basalt, 10-45 cm

Horizon
Depth (cm)
Description
A
0-20
Brownish black (7.5YR 3/2) when moist; clay loam; weak subangular blocky 5 mm; consistence when dry is slightly hard; 20% stones of parent material (8 cm average size); pH 6.0; abrupt boundary.
B
20-30
Dark brown (10YR 3/3) when moist; medium clay; moderate to strong angular blocky 4 mm; consistence when dry is hard; 80% stones of parent material (30 cm average size) and 5% of buckshot; pH 6.0; abrupt boundary.
R
30+
Weathering basalt.

COMPONENT
Proportion %
1
70
2
30
CLIMATE
Rainfall(av.) mm
Annual 510 - 580
Temperature(av.) C
Annual 13
GEOLOGY
Age, rock
Pleistocene, basalt
TOPOGRAPHY
Landscape
Scarp beside main creek including the river channel in places
Elevation (range) m
30 - 198
Local relief (av.) m
38
Drainage pattern
Dendritic
Drainage density km/km2
1.2
Land form
Scarp with local rock outcrop
Creek bed
Position on land form
Slope
Flood plain
Slope (range) %, slope shape
10-30 ; Convex
1-3 ; Straight
NATIVE VEGETATION
Structure
Woodland (?)
Dominant species
E. camaldulensis
SOIL
Parent material
In-situ weathered rock
Unconsolidated sedimentary and in-situ weathered rock
Description
Shallow brown duplex or gradational soils
Black clay soils, uniform texture, coarse structure
Factual key
Surface texture
Clay loam
Clay
Permeability
High
Low
Depth (range) m
0.5 - 1.5
1.0 - 2.5
LAND USE
Grazing
SOIL DETERIORATION
Critical land features
Steep slope, hard setting surfaces
Poorly drained site, low permeability
Processes
Overland flow, sub surface flow
Overland flow, periodic waterlogging
Forms
Minor sheet and rill erosion, low landslip hazard
Streambank erosion, surface compaction


Qbgs - Stony Plains with Duplex Soil on Quaternary Basalt

Stony Plains with Duplex Soils on Quaternary Basalt - QbgsFlat to gently undulating, stony, basalt plains, mainly in the south-east corner. The 62 km2 total area represents 8.9% of the Shire; the third-largest unit.

The most striking feature is the quantity of surface stones. In less extreme cases, these have often been picked up to allow for agriculture and grazing and put in piles or used for stone fences. Apart from the black clayey soils which may occur where the surface is particularly rocky, the soil is similar to, but stonier than in Qbgd. In both cases, however, the clay has low permeability, high plasticity and high shrink-swell potential.

The most common land use is grazing.

SOILS
The most common soil occurs on Component 1.

Stony Mottled Dark Grey Duplex Soils - Coarse Structure

Factual Key: Dd 2.43/CL-LC, 10-30 cm/basalt, 50-100 cm

Horizon
Depth (cm)
Description
A1
0-10
Brownish black (10YR 3/2) when moist; clay loam; weak subangular blocky 5 mm; consistence when dry is hard; surface stones 1 to 30%; pH 6.0; abrupt boundary.
A2
10-15
Greyish yellow brown (10YR 5/3) when moist; clay loam; apedal and massive; consistence when dry is hard; 1-25% basalt stones; pH 6.0; abrupt boundary.
B21
15-35
Brownish black (10YR 3/1) when moist; heavy clay; moderate subangular blocky 40 mm; consistence when slightly moist is very firm; 1-25% basalt stones; pH 7.5; diffuse bGreyish yellow-brown (10YR 4/2) when moist; heavy clay; moderate subangular blocky 60 mm; consistence when slightly moist is very firm; 1-60% basalt atones; pH 8.5.oundary.
B22
35-60+

COMPONENT
Proportion %
1
75
2
30
3
5
CLIMATE
Rainfall(av.) mm
Annual 500 - 560
Temperature(av.) C
Annual 13
GEOLOGY
Age, rock
Pleistocene, basalt
TOPOGRAPHY
Landscape
Stony plains south of Shire
Elevation (range) m
30 - 85
Local relief (av.) m
7
Drainage pattern
Dendritic
Drainage density km/km2
0.4
Land form
Stony plain
Plain
Drainage line
Position on land form
Upper slope (?)
Lower slope (?)
Depression
Slope (range) %, slope shape
1-4 ; Convex
1-3 ; Straight
1-2 ; Straight
NATIVE VEGETATION
Structure
Woodland ?
Dominant species
E. camaldulensis
SOIL
Parent material
In-situ weathered rock
In-situ weathered rook
Alluvium
Description
Stony, mottled dark grey sodic duplex soils, coarse structure
Mottled dark grey sodic duplex soils, coarse
structure
Black clay soil; uniform textures coarse structure
Factual key
Dd 2.43
Dd 2.43
Ug 5.1
Surface texture
Clay loam
Clay loam
Clay
Permeability
Low
Low
Low
Depth (range) m
0.5-1.0
1.0-2.0
1.5
LAND USE
Grazing
SOIL DETERIORATION
Critical land features
Hard Betting surfaces, slowly permeable subsoils
Hard setting surfaces, slowly permeable subsoils
Clay soils in drainage lines
Processes
Overland flow
Overland flow, periodic waterlogging
Overland flow
Forms
Minor sheet erosion, surface compaction
Minor sheet erosion, surface compaction
Minor sheet erosion, surface compaction
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