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

Predominantly 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
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

Gently 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
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

Moderately 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
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

Gently undulating terrain on Tertiary clay, sand and gravel deposits in the north of the Shire. The 24.5 km²represents 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
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

Tgm 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

Moderate 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
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

Moderately 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
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

Gentle 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 ¾) 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
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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