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Soils on Tertiary Unconsolidated and Consolidated Sediments

Tcg - Steep Valley Sides with Duplex Soils - on Variable Sediments | Tgn - Plains with Duplex Soils on Tertiary Sediments | Tgnd - Plains with Duplex Soils on Tertiary Sediments. Drier than Tgn | Tgm - Slopes with Variable Clayey Soils on Tertiary Limestone and Basalt | Tgs - Plains with Duplex Soils on Tertiary Sediments - South of Maude | Tsc - Irregular Surfaces with Shallow Uniform Texture Soils on Tertiary Sedimentary Rock | Tsd - Valley Sides with Duplex Soils on Tertiary Sediments | Tsm - Steep Valley Sides with Clay soils on Variable Parent Materials

Tgn - Plains with Duplex Soils on Tertiary Sediments

Plains with Duplex Soils on Tertiary Sediments - TgnPredominantly fairly deep soils (gently undulating plains) of unconsolidated Tertiary clays, sands, silts and gravels which are scattered throughout the north-central and northwestern parts of the Shire. There are also some broad crests in the Ors unit with Tertiary remnants; and these have been mapped as Tgn where they are large enough. On some of the higher crests there are areas of ferricrete (ironstone layers) with shallow red duplex soils. Patches of deep sand occur randomly in the landscape, particularly in the north-west of the Shire.

The unit occupies 85.0 km2 or 12.1% of the Shire - the second largest unit. The main use of this land is grazing, with some sand and gravel extraction. Some of the poorer areas have been left forested with a low-quality timber.

SOILS

Although there may be differences in soil depth and the structure and mottling of the clay, the major soil of Tgn is fairly consistent. The description below refers to Component 1 and, in particular, describes the most common soil of the extensive undulating plains.

Mottled Yellow Duplex Soils, Fine Structure

Factual Key: Dy 3.41/SL-FSL, 10-40 cm/tertiary sediments, 100-200 cm.

Horizon
Depth (cm)
Description
A1
0-10
Dark brown (7.5YR 3/4) when moist; sandy loam; weak subangular blocky 10 mm; consistence when slightly moist is firm; pH 5.0; abrupt boundary.
A2
10-20
Dull yellowish brown (10YR 5/4) when moist; sandy loam; apedal and massive; consistence when slightly moist is firm; 50% buckshot concentrated at A/B boundary; pH 6.0; abrupt boundary.
B1
20-35
Yellowish brown (10YR 5/6) when moist; few distinct red mottles; medium clay; strong angular blocky 2 mm; consistence when slightly moist is film; 4% buckshot; pH 5.5; diffuse boundary.
B2
35-150
Yellowish brown (10YR 5/6) when moist; with abundant distinct red mottles; medium clay; strong angular blocky 2 mm; consistence when slightly moist is firm; 4% buckshot; pH 5.5; diffuse boundary.
C
150+
Weathering Tertiary sediments.

COMPONENT
Proportion %
1
70
2
15
3
15
4
2
CLIMATE
Rainfall(av.) mm
Annual 585 - 685
Temperature(av.) C
Annual 12
GEOLOGY
Age, rock
Tertiary; gravels, sands and clays
TOPOGRAPHY
Landscape
Undulating plains and broad crest in the north of the Shire
Elevation (range) m
220 - 370
Local relief (av.) m
3
Drainage pattern
Dendritic
Drainage density km/km2
1.6
Land form
Undulating plain
Undulating plain
Drainage lines
Remnant capping- ironstone
Position on land form
Well-drained non-sandy areas
Patches of deep sandy soil
Low lying areas
Some crests - especially near Orm
Slope (range) %, slope shape
1-3 ; Convex and Straight
1-3 ; Convex
1-3 ; Concave
2-4 ; Straight
NATIVE VEGETATION
Structure
Low open forest - woodland
Dominant species
E. viminalis, E. obliqua,
B. radiata, E. rubida,
(E. pauciflora - Durdidwarrah area) Callitris columellaris in lower stratum
E. viminalis
Pteridium esculentum
E. ovata
E. obliqua
B. radiata
Xanthorrhoea australis
SOIL
Parent material
Unconsolidated gravel, sand and
clay
Unconsolidated sand
Unconsolidated gravel, sand and clay
Ironstone (ferricrete) and sandy clays
Description
Mottled, yellow duplex soils, fine
structure
Yellow sand soils, uniform texture
Mottled yellow duplex soils
Red duplex soils over ironstone
Factual key
Dy 3.41
Uc 2.33
Dy 3.42
Dr 2.21
Surface texture
Sandy clay loam to loamy sand
Sand
Clay loam, sandy clay loam
Sandy loam, loamy sand
Permeability
Moderate
High
Moderate
Moderate
Depth (range) m
1.0 - 2.0
0.8 - 3.0
1.5 - 2.5
0.2 - 0.8
LAND USE
Grazing, gravel extraction, mining
SOIL DETERIORATION
Critical land features
Hard setting surfaces, dispersibility, permeability
Low water holding capacity, low nutrient holding capacity
Seasonal high watertables
Hard setting surfaces
Processes
Leaching of salts, overland flow
Leaching
Hard setting surfaces, permeability
Some accumulation of salts, overland
flow, periodic waterlogging
Overland flow
Forms
Minor sheet erosion
Fertility decline
Minor wind erosion
Sheet and rill erosion, minor gully erosion.
Some salting, especially when adjacent to Ordovician sediments
Minor sheet and rill erosion


Tgs - Plains with Duplex Soils on Tertiary Sediments - South of Maude

Plains with Duplex Soils on Tertiary Sediments - South of Maude - TgsGently undulating to flat plains throughout the southern half of the Shire. Having a total area of 95.4 i.e. 13.92% of the Shire, this is the largest unit mapped.

The soils usually have a sandy loam surface layer and the yellow or red subsoil clay overlies unconsolidated clay, sand and gravel of marine Tertiary origin or occasionally isolated ironstone deposits.

The main land use is grazing and cereal cropping, areas remain timbered and are used for recreation, sand and gravel extraction and low-quality forestry.

SOILS

Generally, the most common soil is that of Component 1. There are a few areas where the more sodic, poorer more erodible soil of Component 2 is more common (i.e. around Lethbridge township). The soil described below is representative of Component 1.

Mottled Yellow Sodic Duplex Soils

Factual Key: Dy 3.43/FSL-FSCL, 15-50 cm/tertiary sediments, 80-180 cm.

Horizon
Depth (cm)
Description
A1
0-20
Dark brown (7.5YR 3/3.) when moist; loam fine sandy; hydrophobic; apedal and massive; consistence when dry is slightly hard; pH 7.0; clear boundary.
A2
20-40
Brown (7.5YR 4/3) when moist; sandy loam; hydrophobic; apedal and massive; consistence when dry is slightly hard; pH 7.0; abrupt boundary.
B21
40-60
Bright yellowish brown (10YR 6/6) when moist; with brown and red mottles; medium clay; strong subangular blocky 15 mm; consistence when moist is firm; 1% buckshot 5 mm; pH 6.0; clear boundary.
B22
60-150
Brown (10YR 4/6) when moist with red mottles; clay; strong angular blocky 2 mm; consistence when moist is firm; pH 9.0; clear boundary.
C
150-200+
Bright yellowish brown (10YR 6/8) when moist; with large white mottles; clay; consistence when moist is friable; pH 9.0.

COMPONENT
Proportion %
1
80
2
10
3
9
4
1
CLIMATE
Rainfall(av.) mm
Annual 500 - 585
Temperature(av.) C
Annual 15
GEOLOGY
Age, rock
Tertiary unconsolidated sediments
TOPOGRAPHY
Landscape
Undulating plains throughout the southern half of the Shire
Elevation (range) m
27 - 206
Local relief (av.) m
12
Drainage pattern
Dendritic
Drainage density km/km2
0.7
Land form
Undulating plains
Position on land form
Upper plain
Drainage line
Lower plain
Sand ridge with ferricrete
Slope (range) %, slope shape
2-5 ; Straight
1-2 ; Concave
1-5 ; Straight
3-5 ; Convex
NATIVE VEGETATION
Structure
Woodland to open forest
Dominant species
E. leucoxylon, Acacia pycnantha
E. melliodora, Casuarina stricta,
Dwarf E. viminalis dominates, some
areas south)
E. camaldulensis
E. leucoxylon
Acacia spp
E. viminalis, Acacia pycnantha.
SOIL
Parent material
Unconsolidated clay, silt. sand and gravel
Unconsolidated sediments and recent alluvial deposits
Unconsolidated clay, silt, sand and gravel
Unconsolidated sediments and ferricrete
Description
Mottled yellow duplex and red
duplex exile, both fine structured
Mottled yellow duplex. soils, fine
structure
Mottled yellow sodic duplex soils,
coarse structure
Mottled red duplex soils, acidic
Factual key
Dy3.43 – Dr3.43
Dy 3.43
Dy3.43
Dr 3.21
Surface texture
Fine sandy loam
Sandy loam
Sandy loam
Fine sandy loam
Permeability
Moderate
Moderate to low
Low
High
Depth (range) m
1.0 - 2.0
1-5 - 2.5
2.0
0.7 - 1.8
LAND USE
Cropping, grazing, low quality forestry, ironstone gravel extraction, town sites
Grazing, some cropping, town site
Grazing
SOIL DETERIORATION
Critical land features
Hard setting surfaces
Seasonal high watertables
Slope position
Dispersibility
Hard setting surfaces
Processes
Overland flow
Overland flow
Periodic waterlogging
Overland flow, sub-surface flow
Overland flow
Forms
Minor sheet erosion
Minor gully erosion
Moderate gully erosion
Minor sheet erosion

Tsm - Steep Valley Sides with Clay Soils on Variable Parent Materials

Steep Valley Sides with Clay Soils on Variable Parent Materials - TsmModerately to very steeply sloping sides of river gorges, e.g. along the southern stretches of the Moorabool River, mostly cut through Tertiary deposits. The total area of 25 km2 comprises 5.6% of the Shire.

Because the gorge cuts through many geological strata, the nature of the surface material on the sides of the gorge can be extremely variable. At the top of the slope, there may be younger basalt capping (Quaternary).

Below the younger basalt, there are Tertiary sediments, older basalt (Tertiary), more unconsolidated (Tertiary) sediments including limestone and some quartzite strata and, near the stream, there may be Ordovician slates and sandstones. The meandering of the river affects the steepness of the sides of the gorge and the topography is further complicated by the entrenching of subsidiary streams.

The main land use depends on slope and soil, which change very rapidly along the sides of the gorge. A more detailed study at a larger scale would be essential to plan specific land uses for individual allotments, paying particular attention to the high landslip risk associated with the black clays.

SOILS

Throughout the unit, the most commonly encountered soil types are uniform black or chocolate, self-mulching clays (especially along the Moorabool) or sandy red duplex soils (similar to Tog). Where the soils become very shallow on steeper slopes, (especially over limestone) a grey-brown clay loam with white lime patches may occur.

Black Clay Soils

Factual Key: Ug 5.1/LC-MC, 30-100 cm/lime, clay and sand, 30-100 cm.

Horizon
Depth (cm)
Description
A11
0-5
Brownish black (10YR 3/1) when moist; medium clay; strong angular blocky structure 2 mm; consistence when moist is plastic; pH 6.5; abrupt boundary.
A12
5-50
Black (10YR 2/2) when moist with few large brown mottles; heavy clay; strong angular blocky structure 5 mm with large vertical cracks; consistence when dry, very hard and wet, very plastic; pH 8.5; abrupt boundary.
C
50-200+
Dark brown (10YR 3/4) when moist, with many faint brown mottles; medium clay, moderate sub-angular blocky structure, consistence when moist is plastic; containing 20A lime deposits 8 mm; pH 9.0.

COMPONENT
Proportion %
1
15
2
20
3
5
4
50
5
10
CLIMATE
Rainfall(av.) mm
Annual 500 - 610
Temperature(av.) C
Annual 12
GEOLOGY
Age, rock
Quaternary basalt
Tertiary unconsolidated
sediments-gravel, sand and
clay - some lime
Tertiary (older) basalt
Various Tertiary strata,
unconsolidated sediments,
limestone etc.
Ordovician slates and
sandstones interbedded
TOPOGRAPHY
Landscape
Steep river valley aides south of Maude
Elevation (range) m
30 - 183
Local relief (av.) m
45
Drainage pattern
Dendritic
Drainage density km/km2
Land form
Scarp
Sides of the river valley
Position on land form
Stony upper elope or crest
Upper slope or crest
Mid-slope
Mid-slope
Lower slope
Slope (range) %, slope shape
20-60; Convex/straight
10-50 ; Convex
10-50 ; straight
10-50 ; Straight/concave
10-50 ; Straight/Concave
NATIVE VEGETATION
Structure
Open forest
Dominant species
E. leucoxylon,
E. camaldulensis
(E. viminalis and Acacia
mearnsii on sandy areas)
E. leucoxylon, some
E. melliodora,
E. viminalis
SOIL
Parent material
In-situ weathered basalt
In-situ unconsolidated
sediments with some areas of colluvial basalt
In-situ older basalt with
colluvium from higher land
In-situ unconsolidated
sediments and limestone, with colluvium from higher land.
Some quartzite outcrops
In-situ slates and sandstone with colluvium
Description
Stony, shallow brown clay
soils
Black clays or yellow
duplex soils
Black clays or red-brown
gradational or duplex, soils
Black clays with some are
gradational or duplex soils
and some sandy areas
(Quartzite)
Mottled yellow gradational or
duplex soils
Factual key
Db 1.11 or Ug 5.1
Ug 5.1 or Dy 3.43
Ug 5.1. Gn 3.11
Ug 5.1, Dr 2.13, Dr 2.43, Uc
Gn 3.72 or Dy 3.42
Surface texture
Clay loam
Clay to clay loam
Clay to clay loam
Mostly clay - some sandy
areas
Fine sandy clay loam
Permeability
Moderate
Moderate to low
Moderate
Moderate
Moderate to low
Depth (range) m
0.1- 0.5
0.5 - 1.2
0.3 - 1.0
0.3 - 2.0
0.3 - 1.0
LAND USE
Grazing
Grazing, some cropping on gentler slopes
Grazing
SOIL DETERIORATION
Critical land features
Steep slopes
Moderate to steep slopes, deep black clayey soils
Moderate to very steep slopes,
dispersible clay
Processes
Undercutting,
Overland flows
Overland flow
Forms
Slumping, rock falls
Moderate landslip hazard, rilling on exposed soil
Moderate sheet and rill erosion

Tgnd - Plains with Duplex Soils on Tertiary Sediments. Drier than Tgn

Plains with Duplex Soils on Tertiary Sediments drier than Tgn - TgndGently undulating terrain on Tertiary clay, sand and gravel deposits in the north of the Shire. The 24.5 km2 represents 3.5% of the study area. Tgnd is very similar to Tgn but the climate is drier and, in the north east, it is mainly associated with remnant Tertiary cappings on the broad crests of the steep Ordovician land (Orsd).

The areas of ironstone and quartz gravels are more common, although in many cases, these deposits may not be deep or extensive enough to be of great commercial value.

The soils are mostly moderate to well structured but are often poor in nutrient status. Also, the freely draining sandy soils, together with the high position in the landscape, can lead to low water retention for plant growth during dry periods. As a result, the land is used for grazing or is left as low, open, natural forest.

SOILS

The most common soil type is red mottled yellow duplex soil with a texture of sandy loam to loamy sand at the surface. This occurs mainly on Component 1, although the soils of Component 5 are similar but greyer and those of Component 4 have a high gravel content.

Mottled Yellow Duplex Soils

Factual Key: Dy 3.41/SL-LS, 5-25 cm/unconsolidated clay, sand or gravel, 30-200 cm.

Horizon
Depth (cm)
Description
A1
0-10
Brownish black (10YR 3/1) when moist; loamy sand; apedal and massive; consistence when moist is friable; sometimes with quartz gravels 15 mm; pH 5.0; abrupt boundary.
A2
10-20
Greyish brown (10YR 5/2) when moist; loamy sand; apedal and massive; consistence when moist is friable; sometimes with quartz gravel
0-60%, 20 mm; pH 5.5; abrupt boundary.
B
20-100
Yellowish brown (10YR 5/6) when moist with many fine red-brown mottles; medium clay moderate subangular blocky structure 5 mm; consistence when moist is firm sometimes with quartz gravel 0-40%, 20 mm;
C
100+
Gravelly or sandy clay, etc.

COMPONENT
Proportion %
1
40
2
20
3
15
4
15
5
10
CLIMATE
Rainfall(av.) mm
Annual 550 - 630
Temperature(av.) C
Annual 12
GEOLOGY
Age, rock
Tertiary; gravels, sands and clays
TOPOGRAPHY
Landscape
Undulating plains and broad crests of Tertiary capping in the north of the Shire
Elevation (range) m
170 - 365
Local relief (av.) m
30
Drainage pattern
Dendritic
Drainage density km/km2
0.7
Land form
Lower crests and slopes
Sandy areas
Higher crests with ferricrete
(ironstone)
Lower crests with quartz
gravel
Drainage lines
Position on land form
-
-
-
-
-
Slope (range) %, slope shape
1-5 ; Convex
1-5 ; Convex
1-5, Convex
2-10 ; Convex
1-5 ; Concave
NATIVE VEGETATION
Structure
Low open forest
Dominant species
E. macrorhyncha
E. polyanthemos
(E. obliqua)
(E. camaldulensis near
'Bamganie')
E. viminalis
E. leucoxylon
Acacia mearnsii
bracken (Casuarina
and Callitris in
some areas
E. pacrorhyncha
E. polyanthemos
E. leucoxylon
E. goniocalyx
E. obliqua
Xanthorrhoea australis
Hakea spp.
E. macrorhyncha
E. obliqua
E. polyanthemos
E. leucoxylon
E. sideroxylon
Xanthorrhoea australis
E. macrorhyncha
E. leucoxylon
Leptospermum spp.
Banksia marginate
SOIL
Parent material
Unconsolidated sandy clays
Unconsolidated sands
Ferricrete (ironstone)
Gravels and gravelly clay
and sands
Unconsolidated gravels, sand and
clay
Description
Mottled yellow duplex soils,
fine structure
Uniform sandy soils
Red duplex soils
Gravelly mottled yellow
duplex soils
Mottled yellow duplex soils
Factual key
Dy 3.41
Uc 2.21 or 2.33
Dr 2.31
Dy 3.41
Dy 3.41
Surface texture
Sandy loam - loamy sand
Sand
Loamy sand
Loamy sand - sandy loam
Sandy loam
Permeability
Moderate
High
High
Moderate
Moderate to low
Depth (range) m
0.3 - 2.0
0.7 - 2.0
0.1 - 0.6
0.3 - 1.0
1.0 - 2.0
LAND USE
Grazing, natural forest, recreation, sub-division
Sand extraction
Ironstone gravel
extraction
Quartz-gravel
extraction
SOIL DETERIORATION
Critical land features
Limited permeability
Highly permeable sand
Limited permeability
Seasonal high watertable
Processes
Surface runoff
Leaching
Surface runoff
Periodic waterlogging
Forms
Minor sheet erosion
Nutrient decline
Minor sheet erosion
Surface compaction

Tgm - Slopes with Variable Clayey Soils on Tertiary Limestone and Basalt

Slopes with Variable Clayey Soils on Mixed Tertiary Limestone and Basalt - TgmTgm Gentle to moderate slopes on variety of Tertiary materials in the Moorabool valley. There are only three areas, totalling 1.0 km2, or o.1% of the Shire. The main land use is cropping and, particularly on the black and chocolate clays, market gardens. There are probably many other small areas of Tgm scattered throughout the Tsm unit that were unmappable at the scale of this report.

SOILS.
The deep subsoils and soil parent material usually has a considerable lime content. The dominant soils are either self-mulching, dark clays, similar to those of Ten, or sandy red duplex soils with clay subsoils like those described below. The latter are usually formed when the soil parent material has a higher sand content.

Red Duplex Soils

Factual Key: Dr 8.33/SL-FSL, 10-30 cm/unconsolidated sandy material and limestone, 60-150 cm

Horizon
Depth (cm)
Description
A1
0-10
Dark reddish-brown (5YR 3/3) when moist; fine sandy loam; apedal and massive; consistence when dry is slightly hard; pH 6.0; abrupt boundary.
A2
10-15
Dull reddish-brown (5YR 4/4) when moist; fine sandy loam; apedal and massive; consistence when dry is hard; pH 7.0; abrupt boundary.
B
15-150
Dull reddish brown (5YR 4/3) when moist; heavy clay; strong angular blocky 50 mm breaking to 10 mm; consistence when dry is very hard; pH 8.5; abrupt boundary.
C
150+
Limestone layers with sandy clay.

COMPONENT
Proportion %
1
100
CLIMATE
Rainfall(av.) mm
Annual 510 - 570
Temperature(av.) C
Annual 12
GEOLOGY
Age, rock
Tertiary limestone or basalt
TOPOGRAPHY
Landscape
Gentler slopes in the Moorabool Valley
Elevation (range) m
60 - 170
Local relief (av.) m
30
Drainage pattern
Dendritic
Drainage density km/km2
1.6
Land form
Slopes
Position on land form
-
Slope (range) %, slope shape
3-12% ; Straight
NATIVE VEGETATION
Structure
Open forest
Dominant species
E. leucoxylon, E. camaldulensis
SOIL
Parent material
Limestone, unconsolidated materials with lime, older basalt
Description
Black or chocolate, self-mulching clays on clayey parent material



or

Red duplex soils on sandier parent material
Factual key
Ug 5.1
Dr 2.43
Surface texture
Light to medium clay
Sandy loam
Permeability
Low to moderate
Moderate
Depth (range) m
1.0 - 2.0
1.0 - 2.0
LAND USE
Cropping - some market gardening, grazing
SOIL DETERIORATION
Critical land features
Limited soil permeability, slope gradients
Processes
Overland flow, cultivation
Forms
Moderate sheet and rill erosion

Tsc - Irregular Surfaces with Shallow Uniform Texture Soils on Tertiary Sedimentary Rock

Irregular surfaces with Shallow Uniform Texture Soils on Tertiary Sedimentary Rock - TscModerate to steep elopes and gorges associated with streams that have cut down through the Tertiary sediments. There are only three small areas in the north-west of the Shire, and the total of 0.3 km2 represents only 0.04% of the study area.

In some places the stream has first cut through the basalt plain, and basalt may be found at the top of the scarp as a capping to the Tertiary sediments. Ironstone (ferricrete) outcrops occasionally occur at the top of the Tertiary sediments, while further down the slope there may be quartzite outcrops. The unit is mainly used for grazing and has a fairly high erosion hazard if the soil is exposed.

SOILS

The soils are shallow over the Tertiary clays, sands and gravels. Where there is basalt at the top of the scarp, colluvium from this source often makes the soils darker with well structured clays. A common soil on moderate slopes where basalt is not present is
described below.

Mottled Yellow Duplex Soils

Factual Key: Dy 3.41/SL-SCL, 10-20 cm/tertiary clay, sand and gravel, 30-120 cm.

Horizon
Depth (cm)
Description
A1
0-10
Brownish black (10YR 3/2) when moist; sandy loam; apedal and massive; consistence when slightly moist is firm; pH 6.0; clear boundary.
A2
10-15
Greyish yellow brown (10YR 5/2) when moist; sandy loam; apedal and massive; consistence when slightly moist is firm; pH 6.0; abrupt boundary.
B
15-45
Dull yellow orange (10YR 6/5) when moist; light clay; moderate sub-angular blocky 3 mm; consistence when slightly moist is firm; pH 6.5; clear boundary.
C
45+
Tertiary clay with gravel or sand.

COMPONENT
Proportion %
1
90
2
5
3
5
CLIMATE
Rainfall(av.) mm
Annual 610 – 635
Temperature(av.) C
Annual 12
GEOLOGY
Age, rock
Tertiary gravel, sands and clays and sometimes colluvium from basalt
Tertiary ironstone
Tertiary, quartzite
TOPOGRAPHY
Landscape
Gentle valley
Elevation (range) m
320 - 350
Local relief (av.) m
10
Drainage pattern
-
Drainage density km/km2
-
Land form
Scarp
Rise
Outcrop
Position on land form
-
-
-
Slope (range) %, slope shape
10-30 ; straight - concave
2 ; straight
2-10 ; straight
NATIVE VEGETATION
Structure
Open forest (?)
Dominant species
E. obliqua, E. viminalis
SOIL
Parent material
Unconsolidated gravels, sands and clays
Ironstone
Quartzite
Description
Mottled yellow duplex soils
Reddish shallow uniform soils
Brown shallow uniform soils
Factual key
Dy 3.41
Um 1
Um 1
Surface texture
Sandy loam to sandy clay loam
Loam
Loam - sandy loam
Permeability
Moderate
High
High
Depth (range) m
0.3 - 1.2
0.1 - 0.3
0.1 - 0.3
LAND USE
Grazing
SOIL DETERIORATION
Critical land features
Exposure, routing depth
Processes
Overland flow
Overland flow
Forms
High sheet and rill erosion
High sheet, rill and wind erosion


Tcg - Steep Valley Sides with Duplex Soils - on Variable Tertiary Sediments

Steep Valley sides with Duplex Soils - Variable Tertiary Sediments - TcgModerately to steeply eloping sides of the gorge associated with Bruce's Creek near Bannockburn. The total area of 3.6 km represents 0.596 of the Shire.

The height and slope of the sides vary along the gorge; generally the height and slope decreases toward the north (Component 2 becomes more common) and the slopes are greater on the outside bends than on the inner. The inner bends, in fact, often have small flat terraces.

The main land use is grazing, with some creels associated recreation.

SOILS

The soils vary with slope and position in the landscape but red duplex soils (described below) are common, especially on the upper slopes of Component 1. On the lower slopes, there is a dark, uniform, clay, similar to that described for Tem. On gentler slopes of Component 2, a yellow duplex soil similar to Tgs may occur and the alluvium of Component 3 has similar soils to Qyad.

Red Duplex Soils
Factual Keys Dr 2.13/FSL-SL, 10-40 cm/unconsolidated sediments, 40-100 cm.

Horizon
Depth (cm)
Description
A1
0-20
Dark reddish-brown (5YR 3/3) when moist; sandy loam; apedal and massive; consistence when moist is friable; pH 6.0; abrupt boundary.
B21
20-50
Reddish brown (5YR 4/6) when moist; medium clay; moderate to strong angular blocky 5mm; consistence when moist is firm; pH 7.0; diffuse boundary.
B22
50-60
Reddish brown (5YR 4/6) when moist with fine yellow mottles; medium clay; moderate prismatic; structure 30 mm; consistence when dry is hard; soft accumulations of lime 2096; pH 8.0.
C
60+
Sandy clay with lime (some areas - gravels or quartzite.)

COMPONENT
Proportion %
1
50
2
30
3
20
CLIMATE
Rainfall(av.) mm
Annual 500 – 530
Temperature(av.) C
Annual 13
GEOLOGY
Age, rock
Tertiary unconsolidated sediments with some limestone
TOPOGRAPHY
Landscape
Gorge associated with Bruce's Creek near Bannockburn
Elevation (range) m
46 - 125
Local relief (av.) m
15
Drainage pattern
Dendritic
Drainage density km/km2
4.6
Land form
Scarps and steeper slopes
Moderate to gentle slopes
Creek alluvium and channel
Position on land form
Valley sides - mainly south of Bannockburn
Valley aides - mainly north of Bannockburn
Valley floor
Slope (range) %, slope shape
15-30 ; Straight
5-20 ; Straight
0-3 ; Concave
NATIVE VEGETATION
Structure
Open forest
Dominant species
E. leucoxylon, E. viminalis, E. camaldulensis (lower slopes)
E. camaldulensis (some E. viminalis)
SOIL
Parent material
Unconsolidated sediments including lime
Alluvium
Description
Red duplex soils and dark
clayey uniform soils
Yellow and some red
duplex soils
Uniform soils (variable)
Factual key
Dr 2.13, Ug 5.1
Mainly Um and Ug
Surface texture
Sandy loam-clay
Fine sandy loam Variable
Moderate
Variable
Permeability
Moderate
Moderate to low
Variable
Depth (range) m
10 - 50
30 - 80
50 - 150
LAND USE
Grazing, natural forest
Recreation, some grazing
SOIL DETERIORATION
Critical land features
Steep slopes
Moderate slopes
Low situation affected by flooding from stream
Processes
Overland flow
Overland flow
Overland flow
Forms
Minor sheet and rill erosion
Minor sheet and rill erosion
Streambank erosion, siltation

Tsd - Valley Sides with Duplex Soils on Tertiary Sediments

Valley sides with Duplex soils on Tertiary Sediments - TsdGentle to moderate slopes produced by shallow downcutting of streams mostly in the Tgs unit south-west of Bannockburn. There are only a few occurrences within the Shire and the 1.9 km2 represents only 0.3% of the study area.

At the top of the slope there may be a layer of cemented sand and ferricrete just below the soil. Some of the streams have an associated elope on one side only; the land through which the stream cute having been eroded away on the other side.

The main land use is native forest production and ironstone gravel extraction, with some areas of grazing on the lower slopes. The municipal tip is also located on one of the lower slopes.

SOILS

The soils at the top of the scarp are much redder and have much more ironstone gravel than those of the lower slopes, which progressively become browner, then yellow, down the slope. The latter soils (Component 1) slake readily and are also somewhat dispersible.

Mottled Brown Duplex Soils

Factual Key: Db 2.43/FSL, 15-40 cm unconsolidated clay sand and gravel, 40-100 cm.

Horizon
Depth (cm)
Description
A1
0-5
Dark brown (7.5YR 3/3) when moist; hydrophobic, fine sandy loam; apedal and massive; consistence when dry is soft; pH 5.5; abrupt boundary.
A2
5-25
Dull brown (7.5YR 5/4) when moist; fine sandy loam; apedal and massive; consistence when dry is slightly hard; pH 6.0.
B21
25-40
Dark brown (7.5YR ) when moist; with common distinct brown mottles; light medium clay; weak angular-blocky 5 mm; consistence when dry is slightly hard; pH 8.0.

COMPONENT
Proportion %
1
75
2
25
CLIMATE
Rainfall(av.) mm
Annual 500 – 550
Temperature(av.) C
Annual 15
GEOLOGY
Age, rock
Tertiary unconsolidated sediments (gravel, sand and clay) with a ferruginous stratum at the top of the scarp
TOPOGRAPHY
Landscape
Scarp of sandy creek
Elevation (range) m
60 - 100
Local relief (av.) m
14
Drainage pattern
Dendritic
Drainage density km/km2
1.3
Land form
Lower colluvial elope
Upper slope
Position on land form
-
-
Slope (range) %, slope shape
3-15 ; Concave/straight
10-30 ; Convex
NATIVE VEGETATION
Structure
Low open forest
Dominant species
E. viminalis, E. leucoxylon
Acacia pycnantha, Acacia mearnsii
E. viminalis, Casuarina spp.
Acacia pycnantha
SOIL
Parent material
Colluvium
Ferricrete and ferruginous sands
Description
Mottled yellow or brown duplex soils
Gravelly red duplex soils
Factual key
Dy 3.43 Db 2.43
Dr 2.21
Surface texture
Fine sandy loam
Fine sandy loam
Permeability
Moderate
Moderate
Depth (range) m
0.4 - 1.0
0.3 - 0.8
LAND USE
Gravel stripping (ironstone), natural forest - some grazing
SOIL DETERIORATION
Critical land features
Steep slopes
Moderate to gentle slopes
Processes
Overland flow
Overland flow
Forms
Moderate rill and gully erosion
Moderate sheet and rill erosion
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