Soils on Basaltic Terrain

Tbs - Tertiary Basalt - Steep | Tgn - Upper Tertiary Plains | Tgp - Lower Tertiary Sediments - Gentle | Tsc - Upper Tertiary Scarps | Tsp - Lower Tertiary Sediments - Steep

Tgn - Upper Tertiary Plains

This unit consists of fairly deep soils on unconsolidated Tertiary sands, clays and gravels in a gently undulating plain scattered throughout the central and southern parts of the Shire. The unit occupies 7.38% of the survey area or 68.4 km². The main uses of these areas are grazing and sand and gravel extraction. Some of the poorer areas have been left forested with low quality timber. Some extensive flat areas to the south of the Shire are poorly drained (as component 3). Also in the South of the Shire, there are some outcrops of quartzite of pedological origin.

TGN Red Mottled Yellow Duplex Soils

Factual Key Dy 3.41/SL-FSL, 10-40/tertiary sediments, 100-150

Horizon	Depth (cm)	Description
A1	0-10	Dark brown (7.5YR 3/4) when moist; sandy loam; weak sub-angular 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 & 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 firm; 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; diffuse boundary.
C	150+	Weathering tertiary sediments.

COMPONENT Proportion %	1	2	3	4
COMPONENT Proportion %	70	2	15	13
CLIMATE
Rainfall(av.) mm	650 – 900
Temperature(av.) °C	-
Seasonal growth limitations	-
GEOLOGY
Age, rock	Tertiary; gravels, sands and clays
TOPOGRAPHY
Landscape	Plains
Elevation (range) m	400
Local relief (av.) m	3
Drainage pattern	Dendritic
Drainage density km/km²	4.4
Land form	Undulating plain	Undulating plain	Flat plain	Drainage lines
Position on land form	Well drained non-sandy areas	Patches of deep sandy soil	Poorly drained non-sandy areas	Low lying areas
Slope (range) %, slope shape	1 – 3; Convex	1 – 3; Convex	0 – 2; Flat	1 – 3;; Concave
NATIVE VEGETATION
Structure	Low open forest – woodland
Dominant species	Callitris columellaris in lower stratum (south of Shire area) E. viminalis, E. obliqua, E. radiata, E. rubida, E. ovata, (E. pauciflora – Durdidwarrah area)	Pteridium esculentum, E. viminalis	E. ovata	E. ovata
SOIL
Parent material	Unconsolidated gravel, sand and clay	Unconsolidated sand	Unconsolidated gravel, sand and clay	Unconsolidated gravel, sand and clay
Description	Red mottled, yellow duplex soil, fine structure	Yellow sand soil, uniform texture	Yellow sodic duplex soil, coarse structure	Mottled yellow duplex soil
Surface texture	Sandy clay loam to loamy sand	Sand	Clay loam	Clay loam, sandy clay loam
Permeability	Moderate	High	Low	Moderate
Depth (range) m	2	2	2	2
LAND USE
	Grazing, gravel, extraction, mining
SOIL DETERIORATION
Critical land features	Hard setting surfaces, dispersibility, permeability	Low water holding capacity, low nutrient holding capacity	Hard setting surfaces, permeability	Hard setting surfaces, permeability
Processes	Leaching of salts, overland flow	Leaching	Leaching of salts, overland flow	Some accumulation of salts, overland flow
Forms	Sheet and rill erosion, gully erosion	Fertility decline	Surface compaction, sheet erosion	Sheet and rill erosion, minor gully erosion. Salting, especially when adjacent to ordovician sediments.

Tgp - Lower Tertiary Sediments - Gentle

This unit consists of gentle rises and elopes in the Parwon Valley with brown sodic duplex soils derived from Tertiary sands and silt clay. It has been separated from Tsp on the basis of gentler slopes, soil type and vegetation. The unit covers 0.85% of the Shire or 7.9 km². It is used mainly for grazing although some parts have been cropped for cereals. The erosion hazard is moderately high but is much less than for Tsp.

TGP Brown Sodic Duplex Soils

Factual Key Dy 3.43/FSL, 10-30/tertiary sediments

Horizon	Depth (cm)	Description
A1	0-15	Greyish yellow brown (10YR 4/2) when moist; fine sandy loam; hydrophobic; apedal & massive; consistence when dry is very hard; pH 6.5; clear boundary.
A2	15-25	Greyish yellow brown (10YR 5/2) when moist; with few faint yellow mottles; fine sandy loam; apedal & massive; consistence when dry is very hard & when wet is spewy; pH 6.5; clear boundary.
B1	25-55	Dull yellow (2.5YR 6/4) when moist; with abundant & distinct yellow mottles; sandy clay; weak prismatic 150 mm; breaking down to weak sub-angular blocky 30 mm; consistence when slightly moist is hard; 3% buckshot 5 mm; pH 8.5; abrupt boundary.
B2	55-85	Greyish yellow (2.5YR 7/2) when moist with abundant and prominent yellow mottles; sandy clay; weak prismatic 150 mm breaking down to moderate sub-angular blocky 30 mm; consistence when slightly moist is hard; pH 9.0; clear boundary.
C	85+	Unconsolidated tertiary sediments (yellow mottled white silty clay).

COMPONENT Proportion %	1
COMPONENT Proportion %	100
CLIMATE
Rainfall(av.) mm	500 – 630
Temperature(av.) °C	-
Seasonal growth limitations	-
GEOLOGY
Age, rock	Tertiary sand & silty clay
TOPOGRAPHY
Landscape	Gentle rises & slopes in the Parwan Valley
Elevation (range) m	240 – 270
Local relief (av.) m	40
Drainage pattern	Dendritic
Drainage density km/km²	0.3
Land form	Undulating plains
Position on land form	-
Slope (range) %, slope shape	3 – 10 ; Convex
NATIVE VEGETATION
Structure	Woodland (?)
Dominant species	E. leucoxylon, E. melliodora
SOIL
Parent material	In-situ weathered rock
Description	Brown sodic duplex soils
Surface texture	Fine sandy loam
Permeability	Moderate
Depth (range) m	1
LAND USE
	Grazing, some cereal cropping
SOIL DETERIORATION
Critical land features	Hard setting surfaces, dispersible sub-soils
Processes	Overland flow, movement of salt
Forms	Sheet, gully, tunnel erosion

Tsc - Upper Tertiary Scarps

The unit is composed of the level upper surface of late Tertiary sediments which have been partially buried by the Quaternary lava flow and later exposed where streams have cut down through the basalt due mainly to rejuvenation associated with faulting, or where the more recent lava has terminated. The unit is mainly used for grazing and has a high erosion hazard. The unit extends over 17.0 km² or 1.83% of the survey area.

Soils
Due to the variability of the parent material and, in places, to the influence of the colluvium from the basalt cap there is a wide spectrum of soils. A very strong volcanic influence can be inferred by the very dark clayey, well-structured horizons.

TSC Black Uniform Soils

Factual Key Ug 5.11/Mc, 50-70/Volcanic colluvium over tertiary gravels.

Horizon	Depth (cm)	Description
A11	0-25	Brownish black (10YR 2/2) when moist; medium clay; strong sub-angular blocky 3mm; (self-mulching); consistence when dry is hard; pH 6.5; clear boundary.
A12	25-60	Brownish black (10YR 2/2) when moist; medium clay; moderate prismatic breaking into moderate sub-angular blocky 3 mm; consistence when dry is very hard; 5% of stones; pH 7.0; clear boundary.
BC	60-190	Dark brown (10YR 3/3) when moist; medium clay; moderate to angular blocky 3 mm; 70% stones; pH 7.5; clear boundary to tertiary gravels.

COMPONENT Proportion %	1	2	3
COMPONENT Proportion %	85	5	10
CLIMATE
Rainfall(av.) mm	650 - 900
Temperature(av.) °C	-
Seasonal growth limitations	-
GEOLOGY
Age, rock	Tertiary gravel, sands & clays plus colluvium from basalt	Tertiary ironstone	Tertiary, quartzite
TOPOGRAPHY
Landscape	Original Tertiary plain, partially buried by Quaternary lava flow
Elevation (range) m	243
Local relief (av.) m	10
Drainage pattern	-
Drainage density km/km²	-
Land form	Scarp	Rise	Outcrop
Position on land form	-	-	-
Slope (range) %, slope shape	30 ; Straight – concave	2 ; Straight	1 ; Straight
NATIVE VEGETATION
Structure	Open forest (?)
Dominant species	E. obliqua, E. viminalis, E. radiata
SOIL
Parent material	Alluvial & colluvial basalt and unconsolidated gravels, sands and clays	Ironstone	Quartzite
Description	Black Uniform Soils	Reddish Shallow Uniform Soil	Brown Shallow Uniform Soil
Surface texture	Clay	Loam	Loam
Permeability	Moderate	High	High
Depth (range) m	1	0.10	0.10
LAND USE
	Grazing, occasional cropping (market garden)	Grazing
SOIL DETERIORATION
Critical land features	Slopes	Exposure, rooting depth
Processes	Overland flow	Overland flow
Forms	Sheet and rill erosion	Sheet, rill and wind erosion

Tsp - Lower Tertiary Sediments - Steep

This unit is the deeply dissected plain of the Parwan Valley with isolated hills, some of which have volcanic capping. The unit contains some of the most serious soil erosion in Victoria and as it is in a water supply catchment needs special management. The unit covers 32.2 km² or 3.47% of the survey area. It is used for grazing although some parts should revert to forestry.

Soils
The presence of many active landslips and the influence of colluvium from the basalt cap at the top of the scarp has produced a soil which can be extremely variable over short distances. The soil described is one showing some basalt influence.

TSP Shallow Sodic Gradational Soils, Coarse Structure

Factual Key Gn 3.13/CL-LC, 5-15/Tertiary sediments, 30-50

Horizon	Depth (cm)	Description
A	0-13	Dark brown (7.5YR 3/3) when moist; light clay; moderate sub-angular blocky 5 mm; consistence when slightly moist is firm; 15% of gravel; pH 6.0; clear boundary.
B	13-35	Dark brown (10YR 3/3) when moist; clay; strong angular blocky 25 mm; consistence when moist is firm; 2% weak accumulations of organic matter; pH 8.5; diffuse boundary.
C	35-150+	Dull yellow orange (10YR 6/3) when moist; silty clay; pH 9.0.

COMPONENT Proportion %	1
COMPONENT Proportion %	100
CLIMATE
Rainfall(av.) mm	500 – 630
Temperature(av.) °C	-
Seasonal growth limitations	-
GEOLOGY
Age, rock	Tertiary sands & silty clays
TOPOGRAPHY
Landscape	Deeply dissected plain with isolated hills, some of which have volcanic capping
Elevation (range) m	240 – 400
Local relief (av.) m	130
Drainage pattern	Dendritic
Drainage density km/km²	1
Land form	Closely dissected plain
Position on land form	Crests and slopes
Slope (range) %, slope shape	15 – 35; Concave
NATIVE VEGETATION
Structure	Woodland (?)
Dominant species	E. leucoxylon, E. melliodora, E. microcarpa
SOIL
Parent material	In-situ weathered rock
Description	Shallow sodic gradational soil, coarse structure
Surface texture	Light clay
Permeability	Moderate
Depth (range) m	1
LAND USE
	Grazing
SOIL DETERIORATION
Critical land features	Slope, structure, dispersibility, hard-setting surface
Processes	Leaching, overland flow, sub-surface flow, movement of salt
Forms	Severe landslip, sheet, gully, tunnel erosion

Tbs - Tertiary Basalt - Steep

This unit consists of the steeply dissected Tertiary basalt plain in the Greendale area and around Pykes Creek Reservoir. The area has quite good black clay soils which are presently used for grazing and in gentler sloping areas, some cereal cropping. The latter could possibly be used more intensively. The unit represents 1.07% of the Shire and covers 9.9 k_m²_.

TBS Black Clay Soils Uniform Texture Coarse Structure^,

Factual Key Ug 5.12/LC-MC, 5-20/Basalt, 25-50

Horizon	Depth (cm)	Description
A11	0-5	Brownish black (7.5YR 2/2) when moist; light medium clay; strong angular blocky 3 mm (self-mulching); consistence when moist is friable; pH 5.5; clear boundary.
A12	5-25	Brownish black (7.5YR 2/2) when moist; medium clay; strong angular blocky 5 mm; consistence when moist is friable; pH 6.5; clear boundary.
	25+	Weathering basalt.

COMPONENT Proportion %	1	2
COMPONENT Proportion %	90	10
CLIMATE
Rainfall(av.) mm	685 – 736
Temperature(av.) °C	-
Seasonal growth limitations	-
GEOLOGY
Age, rock	Tertiary basalt
TOPOGRAPHY
Landscape	Deeply dissected plains in the Greendale area
Elevation (range) m	400 – 550
Local relief (av.) m	40
Drainage pattern	Dendritic
Drainage density km/km²	1.8
Land form	Scarps & slopes	Stony areas
Position on land form	-	Localised surface capping
Slope (range) %, slope shape	8 – 50 ; Convex	1 – 3 ; Convex
NATIVE VEGETATION
Structure	Open forest (?)
Dominant species	E. viminalis, E. ovata
SOIL
Parent material
Description	Black clay soils, uniform texture, coarse structure	Red shallow gradational soil
Surface texture	Clay	Clay loam
Permeability	Moderate	High
Depth (range) m	1	<1
LAND USE
	Grazing; cropping (cereal)	Grazing
SOIL DETERIORATION
Critical land features	Slopes, permeability	Slopes
Processes	Overland flow – Subsurface flow	Overland flow
Forms	Sheet erosion – Landslip	Sheet erosion

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