Soil/Landform Unit 198

Longitudinal coastal dunes with back swamps and estuaries near Breamlea

Area:

930 ha

0.07% of CMA region

Along the coast from Breamlea to Eastern View, coastal dunes occur discontinuously. In some localities a primary and a secondary dune form a thin barrier between the sea and the Paleogene sediments, but in the locality of Point Impossible the dune system is more complex and extensive. The foredune and secondary dune material is

aeolian

sand and shell grit. On older dunes, mobilisation of calcium carbonate has resulted in the formation of calcarenite, which may outcrop on blowouts or steep slopes. Away from these calcarenite pavements, the soils are freely drained

calcareous

sands. The exposed calcarenite pavements may support red calcareous gradational soils, but extensive sheet erosion has removed most of this material. Recreation and access to the foreshore are the main land uses. Some buildings have been sited in these dunes at Breamlea and Fairhaven. Native grasses and shrubs that colonise these dunes are very sensitive to disturbance and once devoid of vegetative cover, wind erosion is likely to occur. Hand planting of

Ammophila

arenaria

has been necessary to restabilise many areas.

Point Roadknight
	Coastal cliffs and dunes

Component	1	2	3	4	5
Proportion of soil-landform unit	20%	50%	25%	2%	3%
CLIMATE Rainfall (mm)	Annual: 600–750, lowest January (30), highest August (75)
Temperature (^oC)	Annual: 14, lowest July (10), highest February (18)
Seasonal growth limitations	Temperature: less than l 0^oC (av.) July Precipitation: less than potential evapotranspiration mid October–early April
GEOLOGY Age and lithology	Quaternary coastal aeolian sand dunes, alluvium and shell grit			Cemented Paleogene marine clay, fluvial sand and gravel deposits (calcarenite and travertine)
Geomorphology	6.2.5 Alluvium, alluvial terraces, floodplains and coastal plains of the Sedimentary Western Plains
LANDUSE	Uncleared areas: Passive and active recreation; foreshore access; nature conservation; sand extraction Minor cleared areas: Recreational facilities; refuse tip; foreshore access; residential
TOPOGRAPHY Landscape	Longitudinal coastal dunes to the east of the Otway Range
Elevation range (m)	0–25
Local relief (m)	15
Drainage pattern	-
Drainage density (km/km²)	1.7
Landform	Foredunes	Shifting dunes	Older more stable dunes		Interdune corridors
Landform element	Windward exposed slope	Leeward and windward slopes	Gentler slope	Steeper slope	-
Slope and range (%)	40 (10–65)	30 (5–65)	9 (0–20)	15 (5–30)	3 (0–7)
Slope shape	Irregular	Irregular	Convex	Linear	Concave
NATIVE VEGETATION Ecological Vegetation Class	Tussock grassland	Open heath	Low woodland	Low woodland	Possibly open heath
Dominant species	Spinifex hirsutus, Tetragonia tetragonioides	Helichrysum paralium, Leucopogon parviflorus	Melaleuca lanceolata, Leptospermum laevigatum, Leucopogon parviflorus	Melaleuca lanceolata, Leucopogon parviflorus, Acacia longifolia	Helichrysum paralium
SOIL Parent material	Coarse sand, shell grit	Coarse sand, shell grit	Coarse sand, shell grit	Calcarenite coarse sand	Calcarenite, travertine
Description (Corangamite Soil Group)	Brown, grey and yellow calcareous sand soils (12)	Brown, grey and yellow calcareous sand soils (12)	Brown calcareous sand soils (12)	Stony black calcareous sand soils (8)	Red calcareous gradational soils (24)
Soil type sites	CLRA41, CLRA44, OTR415	CLRA41, CLRA44, OTR415	OTR415	OTR608, CLRA44	OTR489
Surface texture	Coarse sand	Coarse sand	Loamy sand	Loamy sand	Sandy loam
Permeability	Very high	Very high	Very high	Moderate	Very low
Depth (m)	>2	>2	>2	>2	0.3
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS	Marine erosion and accretion occur seasonally. Native vegetation is sensitive to trampling and disturbance. Weakly structured sands are prone to wind erosion. Low inherent fertility and high permeability lead to nutrient decline.	Native vegetation is sensitive to trampling and disturbance. Weakly structured sands are prone to wind erosion. Low inherent fertility and high permeability lead to nutrient decline.	Weakly structured sands are prone to wind erosion. Low inherent fertility, high alkalinity and high permeability lead to nutrient decline.	Weakly structured sands with restricted drainage on steep slopes are prone to sheet erosion. Low inherent fertility and high alkalinity lead to nutrient decline.	Low permeability and weak structure lead to sheet erosion, exposing calcarenite pavement.

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