Koonwarra (Ko)

Geology

Mesozoic sediments (Cretaceous) - consisting of sandstones, siltstones and mudstones.

Landform

Undulating hills. The slopes are mostly gently inclined (3-10%) with small areas of moderate slopes (10-32%).

This mapping unit occurs on the down-throw side of the faults and monoclines. It is less dissected than the Strzelecki unit.

Land Use

Mostly plantation forestry but smaller areas are used for grazing - predominantly beef and dairy cattle.

Photo: Koonwarra Landscape

Typical undulating hills landscape of the Koonwarra unit near Fish Creek.

Soils

Component 1
Most of this mapping unit is described as gently inclined slopes. The surface soils are generally brownish-grey to grey-brown fine sandy loams to fine sandy clay loams. Below about 20 cm the soil is generally lighter in colour and often conspicuously bleached or sporadically bleached. Yellowish-brown and grey-brown mottled medium clays occur abruptly from about 30 to 50 cm and often the ped faces in the upper part of this horizon are darkly stained by organic matter. Bedrock generally occurs between 1 and 2 m (Site SG7 and Site SG11 are examples of Brown Kurosols that occur in this unit). In areas close to the coast, the subsoils may become slightly sodic and these soils are referred to as Sodosols. Site GP51 is an example of a Sodosol that occurs near Dalyston.

Component 2
This is a minor component that occurs on the steeper slopes. The soils are similar to those described in the previous mapping unit and have grey-brown clay loam surface soils, grading into yellowish grey-brown clay loams or light clays at about 35 cm. At 60 cm, greyish yellow-brown light clay or occasionally medium clays are encountered. These become yellow-brown with light brownish grey mottles with depth. Fragments of rock generally appear by about 80 cm and continue until about 1.2 m when rock becomes impenetrable.

Occurrences

This mapping unit is associated with the low hills around Wonthaggi and Koonwarra.

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