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Soil/Landform Unit 21

Landform Unit Description

Unit 21 image a
Plateaux of the dissected landscape near Happy Valley in the Western Uplands
      Area: 3709 ha
      0.28% of CMA region

      This hills and plains unit is a member of the dissected Western Uplands. This unit of only two occurrences predominantly consists of a Neogene plain (plateau) which has been dissected and some moderately steep Palaeozoic low hills in the Pitfield, Cape Clear area. This unit is either close to or forms a boundary between the Western Uplands and the Western Plains. The soils are sodic often acidic, mottled brown texture contrast soils (Sodosols, Kurosols) on the plains, and shallow mottled red and yellow gradational soils (Dermosols) on the hills. The lighter surface soils are prone to nutrient decline and sheet and rill erosion. Sheet, rill, gully and minor mass movement are concerns on the steeper slopes. Nutrient levels are low in this unit and most of the soils are dispersible, the Neogene clays particularly so (due to sodicity). The predominant land use is grazing, with some mineral extraction on the plains and some hillslopes, while forestry, recreation and conservation are confined to the hills.
Unit 21 geomorphology

Unit 21 image b
The main land use of these plains and slopes includes
grazing and cropping (cereal)
Unit 21 cross section

Unit 21 graph

Unit 21 image c
Gully and tunnel erosion is common on slopes and
roadsides near Cape Clear

Component
1
2
3
4
5
6
Proportion of soil-landform unit
1%
12%
1%
11%
74%
1%
CLIMATE
Rainfall (mm)

Annual: 660-720
Temperature (oC)
Minimum 8, Maximum 19
Precipitation less than potential evapotranspiration
October-March
GEOLOGY
Age and lithology

Neogene fluvio-marine sand, Orodivician marine sandstone and shale and minor Quaternary basalt
Geomorphology
LANDUSE
Uncleared areas: Hardwood forestry; nature conservation
Cleared: Sheep and beef cattle grazing; gravel extraction; mining
TOPOGRAPHY
Landscape

Moderate steep low hills and gently undulating plain
Elevation range (m)
185-324
Local relief (m)
5-35
Drainage pattern
Dendritic
Drainage density (km/km2)
2.5
Landform
Low Hill
Plain
Landform element
Southern slope
Northern slope
Drainage line
Creast
Non-sandy areas
Patches of deep sandy soil
Slope and range (%)
15 (10-25)
15 (10-25)
4 (2-10)
7 (0-15)
1 (1-3)
2 (1-3)
Slope shape
Straight
Straight
Concave
Convex
Convex
Convex
NATIVE VEGETATION
Structure

Tall open forest

Open forest

Open forest

Open forest

Low open forest-woodland

Low open forest-woodland
Dominant species
E. obliqua, E. ovata,
E. radiata, E. viminalis
E. dives, E. obliqua,
E. viminalis, E. radiata
E. viminalis, E. radiata,
E. obliqua
E. obliqua, E. dives,
E. viminalis, E. radiata
E. viminalis, E. obliqua,
E radiata, E. rubida,
E. ovata, E. pauciflora
Pteridium esculentum,
E. viminalis
SOIL
Parent material

In situ weathered rock

In situ weathered rock

Unconsolidated sediments

In situ weathered rock

Unconsolidated gravel, sand and clay

Unconsolidated clay
Description
(Corangamite Soil Group)
Mottled brown, grey or yellow gradational soils, fine structure (25)
Mottled brown, grey or yellow gradational soils, fine structure (25)
Black gradational soils (34)
Shallow stony red gradational soils (40)
Mottled brown, grey or yellow texture contrast soils, fine structure (15/13)
Bronw, grey or yellow sand soils (8)
Soil type sites
BD10, CLRA53, MM168
BD10, CLRA53, MM168
BD10, CLRA53, MM168
OTR499, 5109, SW67
CLRA5, OTR608, OTR740
Surface texture
Fine sandy loam
Fine sandy loam
Clay loam
Gravelly loam
Sandy loam, sandy clay loam
Sand
Permeability
High
High
Moderate to low
High
Moderate
High
Depth (m)
1
1
1.5
0.5
2
2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS
Overland flow across the steeper slopes encourages sheet and rill erosion. Potential for minor mass movement.
Hardsetting surface soils on steep slopes can lead to compaction and are subject to overland flow and sheet and rill erosion.
Drainage lines are subject to seasonally high watertable and periodic waterlogging with some gully erosion. Hardsetting surface soils lead to surface compaction.
Hardsetting surface soils can lead to compaction and are subject to overland flow and sheet and rill erosion on moderate slopes.
Hardsetting surface soils lead to overland flow and sheet and rill erosion. Moderate permeable, leaching of salts and dispersive subsoils lead to gully erosion.
Hardsetting surface soils with low fertility lead to minor wind erosion. Highly permeable, leaching and dispersive subsoils with low fertility are common.
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