5.5.2 Low ridge tops with remnant aeolian sand and oriented swales with lakes and lunettes (south of Little Desert - Kowree, Goroke)

This unit is located in western Victoria, clearly bounded by the Big Desert to the north and the little Desert to the south. The South Australian border is the artificial western boundary and the Wimmera River Valley (Lowan Salt Valley) is the eastern boundary. Similar terrain is found to the south of the Little Desert.

This unit is dominated by a series of parallel and subparallel ridges orientated NNW/SSE, interspersed with similarly aligned valleys or swales. This pattern remains discernible in the siliceous dunefield units (5.2) to the north and south. This landform pattern is at its most distinct in this unit with the relative relief of the ridges ranging from 10 to 60 m. The major ridges (Diapur/LawloitRange/Propodollah) have an amplitude of about 5 km with slopes of up to 8%, while the smaller ridges have an amplitude of 2 km and slopes up to 5%. The larger ridges have a complex of components including elevated swales/valleys.

The intervening valley floors may extend to plains in the west and nearer the eastern boundary. These valley floors are dominated by lagoonal deposits, which can be quite shallow as well as the occasional swamp. There is the occasional sandy dune.

The ridges consist of Parilla Sand ferruginised at the surface and exposed on the larger ridges, while Woorinen Formation calcareous sandy clay regolith material (parna) covers most of the smaller ridges. Reworking of the Parilla Sand crests has resulted in a younger unconsolidated silceous sand (Lowan Sand) on the crests and on the valley floors/plains. The valley floors have younger lagoonal deposits consisting of expansive (cracking) dark organic clays, which may be quite shallow at their edges. This plains of Quaternary lacustrine and aeolian sediments is part of a NNW/SSE orientated terrain surrounded by associated rises/ridges and other ridge /depression landscapes. Drainage is strongly aligned to the terrain with little surface expression apart from local depressions, including swamps and lakes.

Sandy surfaced sodic texture contrast soils (Sodosols) and sandy soils (Rudosols and Tenosols) are generally acidic and occur on the Parilla Sand exposures while sodic (and calcareous) red texture contrast soils occur on the Woorinen Formation material, mainly on the smaller ridges. Grey and black cracking clay soils (Vertosols) formed on lagoonal deposits dominate the swales and valley floors. Vegetation is dominated by woodland and wetlands on expansive plains including Plains Woodland, Shallow Sands, Damp Sands Herb-rich Woodland and Red Gum Wetland. Plains Grassy Woodland is found mostly on freely draining soils. Lunette Woodlands, Heathy Woodland, Cane Grass Wetland, Aquatic Herbland, Shallow Sands Woodland and Escarpment Shrubland are also found on these plains. On sandy dunes and rises (ridges), Shallow Sands Woodland, Damp Sands Herb-rich Woodland, Sand Heathland, Plains Grassy Woodland, Low Rises Woodland and Sandstone Ridge Shrubland are prominent. In the poorer drained swales, swamps, depressions and associated plains, Lignum Swampy Woodland, Freshwater Lake Mosaic, Dune Soak Woodland, Brackish Wetland, Plains Savannah, Shallow Sands Woodland, Plains Woodland, Drainage-line Woodland, Heathy Woodland, Brackish Lake Mosaic, Lignum-Cane Grass Swamp Drainage-line Woodland and Red Gum Wetland occur. Yellow box is the dominant primary vegetation on the ridges with some Casaurinas also occuring. The valley floors are dominated by black box as their primary vegetation.

Sheet erosion is relevant to any sloping terrain, with water repellancy as an associated issue in this unit. Wind and gully erosion is a land degradation issue particularly relevant to the larger ridges. Water repellency and infiltration are issues on the red texture contrast soils particularly where surface soil horizons are shallow. Waterlogging may be an issue on the valley floors depending on rainfall events.

The Parilla Sand deposits provide roading material and are a source of heavy minerals (Campbell et al. 2003).

Soil-landform unit	Unit description	Area (km²)
Apsley plains	Plain	441
Benayeo gilgai plains	Plain	191
Diapur ridge	Undulating stranded beach ridge	25
Edenhope undulating plains	Plains with subdued ridges	196
Fairview plains	Gently undulating plains	20
Goroke plains and rises	Plain with prominent ridges	537
Horsham lake and lunettes	Lake and lunette	4
Horsham lake-lunette cluster	Lake-lunette cluster	4
Kowree undulating sand plains and ridges	Undulating sand plain and ridges	1059
Rybybolite plains	Plains	40
Langkoop clay plain	Clay plain	40
Merryvale lakes and ridges	Lakes and ridges	14
Minimay plains	Gently undulating plains	41
Mosquito Creek swamps sand plains	Swampy sandplain	104
Neuarpur undulating plains	Plains with subdued ridges	172
Nurcoung plains	Plains	139
Powers Creek sand plains	Gently undulating sand plains	79
Ullswater plains and rises	Plains with parallel ridges	609
West Wimmera wetlands	Lake	129

Figure 18 Series of lakes and swamps in swales with sand dunes masked by remnant vegetation near Karnak

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