6.2.1 Plains with depositional ridges (Kanawinka)

Located in the very south-west corner of the WCMA region is the Kanawinka sand plains and dunes soil-landform unit. More pronounced and quite extensive in the south-west of the Glenelg Hopkins CMA region, the sand plains and dunes recognise a change from the low ridge tops with remnant aeolian sands and oriented swales with lakes and lunettes geomorphological division (unit 5.5.2) to this landscape. While the surface expression in terms of topography, soils and vegetation is extremely similar, this geomorphology reflects a transition to later sediments deposited further southwest into Victoria and South Australia.

Sandsheets and dunes of this landscape include dunes with crests, slopes and associated plains with little relief (approximately 5 m) and poorly defined surface drainage. Occurring between 120 and 140 m, slopes are level to gently inclined and dominated by aeolian sands and silts. Plains and swamps are also prominent with swamp beds and sandsheets common in this rather subdued plains landform.

Parent material comprises Neogene marine sand and silt (Parilla Sand), Quaternary aeolian dune sand (Lowan Sand) and paludal silt and clay of swamp deposits. Underlying Parilla Sand is strongly ferruginised at the surface where infrequently exposed on areas of slight dissection. Reworking of the Parilla Sand has resulted in the younger unconsolidated siliceous sand (Lowan Sand) developing as sand plains and dunes. Swamps with younger lagoonal deposits consisting of expansive (cracking) dark organic clays also occur.