Soil/Landform Unit 8

Landform Unit Description



Unit 8 image a
Looking north towards the Bamganie State Forest
      Area: 3032 ha
      0.23% of CMA region

      The undulating low hills in the area of the Bamganie State Forest near Meredith are composed of Ordovician marine sandstone and shale with Neogene fluvio-marine sands. The hillslopes support a wide range of vegetation classes including Grassy Dry Forest, Creekline Herb-rich Woodland and Valley Grassy Forest. Dominant species are Eucalyptus obliqua, E. dives, E. radiata and E. viminalis. The low fertility and the low water holding capacity of the soils have discouraged further clearing except on some of the gentler, lower slopes that support native pastures. Soils include an association of sandy mottled texture contrast soils with structured or massive subsoils that occur on the hillslopes with sandy equivalents occurring on upper slopes. These soils can be prone to gully erosion, which is minor to moderate in severity in some cleared areas.
Unit 8 geomorphology

Unit 8 image b
Soils of the gullies and slopes can be quite sandy and of some depth.
The presence of bracken fern highlights the light sandy soils of this unit		Unit 8 cross section

Unit 8 graph

Unit 8 image c
Gully erosion is of minor to moderate severity across this unit. Dispersible subsoils are susceptible is exposed.

Component
1
2
3
4
5
6
7
8
Proportion of soil-landform unit
1%
30%
25%
5%
4%
15%
15%
5%
CLIMATE
Rainfall (mm)

Annual: 670
Temperature (oC)
Minimum 8; Maximum 18
Precipitation less than potential evapotranspiration
October-March
GEOLOGY
Age and lithology

Ordovician marine slates and sandstone

Neogene gravels, sands and clays
Geomorphology
LANDUSE
Uncleared: Nature conservation; firewood and sawlogs
Cleared: Grazing; gravel extraction; mining
TOPOGRAPHY
Landscape

Undulating hills
Elevation range (m)
180-370
Local relief (m)
3-65
Drainage pattern
Dendritic
Drainage density (km/km2)
3.5
Landform
Hills
Depressions
Ralling plains
Undulating plains
Level plains
Landform element
Moist protected slopes
Dry exposed slopes
Crests
Drainage line
Crests
Long gentle slopes
Well-drained non-sandy areas
Poorly drained non-sandy areas
Slope and range (%)
15
15
3
3
1-3
3-9
1-3
0-2
Slope shape
Straight
Straight
Convex
Concave
Convex
Straight
Convex
Flat
NATIVE VEGETATION
Ecological Vegetation Class

Grassy Dry Forest (13.5%); Creekline Herb-rich Woodland (3.4%); Valley Grassy Forest (1.9%)
Dominant species
E. obliqua, E. dives,
E. radiata, E. viminalis
E. obliqua, E. dives,
E. radiata, E. viminalis
E. ovata, E. radiata,
E. viminalis, E. obliqua
E. obliqua, E. radiata
E. obliqua, E. viminalis
Callitris columellaris
E. viminalis, E. obliqua
E. raidata, E. rubida
E. ovata, E. pauciflora
E. ovata
SOIL
Parent material
In situ weathered sandstone and shale
In situ weathered sandstone and shale
In situ weathered sandstone and shale
Alluviu, clay, silt, sand, gravel
In situ weathered sandstone and shale
In situ weathered sandstone and shale
Unconsolidated gravel, sand and clay
Unconsolidated gravel, sand and clay
Description
(Corangamite Soil Group)
Red mottled brown, grey or yellow gradational or texture contrast soils, fine structure (26)
Red mottled brown, grey or yellow gradational or texture contrast soils, fine structure (25)
Shallow stony red and yellow gradational soil (25)
Black gradational (variable) and mottled yellow/red gradational soil (34)
Shallow stony red gradational soil (25)
Red mottled yellow texture contrast soil (26)
Red mottled, brown, grey or yellow texture contrast soil, fine structure (13)
Bronw, grey or yellow sodic texture contrast soil, coarse structure (14)
Soil type sites
BD10, CLRA53, CLRA57
BD10, CLRA53, CLRA54
Surface texture
Fine sandy loam
Fine sandy loam
Gravelly loam
Clay loam
Gravelly loam
Loamy clay
Sandy clay loam to loamy sand
Clay loam
Permeability
High
High
High
Moderate to low
High
Moderate to low
Moderate
Low
Depth (m)
1
2
0.5
1.5-2.5
0.6
1
2
2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS
Hardsetting surface soils on steep slopes are subject to overland flow and sheet and rill erosion.
Harsetting surface soils can lead to compaction and are subject to overland flow and sheet and rill erosion on steep slopes.
Hardsetting surface soils can lead to compaction and are subject to overland flow and sheet and rill erosion on moderate slopes.
Organic surface soils grading to deep medium or heavy texture soils with vertic properties.
High silt content leading to erosion prone soils. Stongly acidic and low nutrient availability with generally shallow organic surface soils.
High silt conent with sodic subsoils can lead to erosion prone soils. Strongly acidic and low nutrient availability with generally shallow organic surface soils.
Presence of buckshot on top of the subsoil is a common feature. Sandy upper soil but subsoils of low permeability.
Presence of buckshot on top of the subsoil is a common feature. Sandy upper soil but strongly sodic subsoils of low permeability. Harsetting surfaces, surface compaction and overland flow lead to sheet erosion.
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