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Soil/Landform Unit 71

Landform Unit Description

Unit 71 image a
The valley of the Painkalac Creek remains virtually uncleared, and is pupular with bush walkers and picknickers from nearby resorts
      Area: 3142 ha
      0.24% of CMA region

      The terrain inland from Eastern View and Aireys Inlet consists of spurs and ridges with steep slopes and deep valleys. The outcropping Paleogene sediments are partly unconsolidated, but many beds are composed of quartzitic sandstones and siltstone. The lower parts of the landscape often possess outcrops of Cretaceous sediments. Open forests of Eucalyptus obliqua, E. sideroxylon and E. radiata occur over most of the landscape on texture contrast soils. The drier north and west facing slopes and steep slopes carry woodlands on shallow stony soils. The Cretaceous outcrops can be recognised by the increase in understorey cover and the occurrence of species such as Acacia mucronata and Cassinia longifolia. Some selective logging of these hills is undertaken, but the main use is for recreation such as bushwalking and picnicking. The steep slopes are popular with trail bike riders, and this often results in severe damage to the vegetation and soil.
Unit 71 geomorphology

Unit 71 image b
Steep northerly facuing slopes near the hillcrest
(note the consolidated sands and clays of this roadside cutting)
Unit 71 cross section

Unit 71 graph

Unit 71 image c
Open forest with
E. obliqua and E. cypellocarpa common

Component
1
2
3
4
5
6
Proportion of soil-landform unit
30%
20%
7%
25%
8%
10%
CLIMATE
Rainfall (mm)

Annual: 80-1050, lowest January (40), highest (August (110)
Temperature (oC)
Annual: 13, lest July (8), highest February (17)
Precipitation less than potential evapotranspiration
Temperature: less than 10oC (av.) mid June-mid August
Precipitation less than potential evapotranspiration mid Novembr-mid March
GEOLOGY
Age and lithology
Paleogene unconsolidated fluvial clay, silt and sand; some silica cemented quartzitic sandstone and siltstone

Cretaceous fluvio-volcanic sandstone and mudstone
Geomorphology
LANDUSE
Uncleared areas: Nature conservation; hardwood forestry; active and passive recreation
Minir cleared areas: Residential; active recreation
TOPOGRAPHY
Landscape

Deeply dissected hills
Elevation range (m)
0-240
Local relief (m)
100
Drainage pattern
Dendritic
Drainage density (km/km2)
2.5
Landform
Hills
Valley floors
Hills
Landform element
Crest and north and west slopes
Lower slope and fan
Alluvial terrace
South and east slopes
Steep north slope
Steep lower slope
Slope and range (%)
18 (6-45)
7 (1-14)
1 )0-2)
18 (10-40)
55 (40-60)
45 (30-60)
Slope shape
Convex
Concave
Linear
Convex
Linear
Linear
NATIVE VEGETATION
Structure

Woodland

Open forest

Open forest

Open forest

Low woodland

Open forest
Dominant species
E. radiata, E. obliqua, E. baxteri,
E. sideroxylon
E. sideroxylon, E. cypellocarpa,
E. obliqua, E. baxteri
E. obliqua, E. ovata. E. sideroxylon
E. obliqua, E. cypellocarpa
E. nitida, E. obliqua,
Casuarina littoralis
E. obliqua, E. radiata,
E. sideroxylon
SOIL
Parent material

Clay, silt and sand

Alluvial clay, silt and sand

Alluvial clay, silt and sand

Clay, silt and sand

Mainly quartzitic sandstone and siltstone

Feldspathic sandstone and mudstone
Description
(Corangamite Soil Group)
Red-yellow/brown texture contrast soils (27)
Brown, grey or yellow gradational soils, weak structure (29)
Yellow-brown sodic texture contrast soils, coarse structure (27, 14)
Red-yellow/brown texture contrast soils (27)
Stony brown, grey or yellow gradational soils (29)
Brown texture contrast soils (6)
Soil type sites
OTR497
CLRA13, SW40, OTR742
Surface texture
Fine sandy loam
Sandy loam
Fine sandy loam
Fine sandy loam
Gravelly sandy loam
Loam
Permeability
Moderate
High
Low
Moderatw
Very high
Moderate
Depth (m)
>2
>2
>2
>2
0.7
0.9
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS
Weakly structured surface soils on steep slopes are prone to sheet erosion and compaction. Clay subsoils on steep slopes are prone to landslips.
Weakly structured soils receiving surface runoff from adjacent areas are prone to scour gullying, siltation and flooding.
Weak surface structure is prone to compaction leading to reduced permeability and increased overland flow.
Weakly structured surface soils on steep slopes are prone to sheet erosion and compaction. Clay subsols on steep slopes are prone to landslips
Stony shallow soils with weak structure and low water holding capacity on dry steep slopes are prone to sheet erosion and landslides.
Steep slopes and weakly structured surfaces lead to sheet erosion. Clay subsoils on steep slopes subject to periodic saturation are prone to landslips.
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