Landforms

Driving The Oodnadatta Track you will see lots of different landforms. Floodouts and watercourses are common. In between are cast sand and gibber (small red rock) plains and tableland dotted with mesas (uniqually individual ecosystems).

In several places the Oodnadatta Track passes through sand dune country where the dominant features are dunes and flat areas between them known as swales. There are various salt lakes like Lake William and the world renown, Lake Eyre. The Peake and Denison Ranges in the north and Willouran Ranges close to Marree, the rocky out crops at intervals along the Track and the dramatic shapes of Hermit and Pigeon Hill at Bopeechee provide further variations in the landscape. Each land type supports different vegetation. 

You may also notice small depressions where the ground cover is denser and more diverse because water and nutrients accumulate there and are held for extended periods. These are gilgais (crab holes to the locals) ranging from a few metres in diameter up to 10 meters in the gibber plains.

Walk along a dry creek bed where the soil has been nourished regularly by the nutrients washed down after rains. You will usually see a much greater variety of plants than on the surrounding plains. You will notice this if you stop at some of the larger watercourses you cross as you travel the Oodnadatta Track. Here too you will find gidgee and coolibah: two of the largest trees that need the deep moisture that accumulate along these watercourses. By contrast there is very little vegetation on the sides of most mesas (flat topped hills).

Sand dunes and swales

 the soft country

Dunes like these provide excellent shelter, comfortable campsites, and timber and food for the local Aboriginal people. They are largely stable with movement restricted to the crests. The vegetation you see on them, in particular the sandhill canegrass, sandhill wattle and horse mulga helps prevent movement of the sand. 

A short walk on an undisturbed dune will reveal multitude of tracks and burrows of the wildlife that inhabit this country, take time to do this and see how mant different types of tracks you can spot in the sand. 

The conversion of much of central Australia into sand dunes has been a product of low elevations, widespread sediment deposition, aridity and the extremes of wildly fluctuating climate over the last million years. Some geologists believe the dunes formed in the last 8,000 to 10,000 years; others suggest upto 200,000 years.

Why do dunes vary so much in colour?

Most dunes are brownish pink or brick red; some are yellow-brown or grey-brown; others near Lake Eyre are much lighter.  The lighter-coloured dunes are generally found closer to the sand source. For example, where they have blown in from the flood plainsalong Eyres Creek and Goyders lagoon, they are white or light yellow. Generally dunes from a long way from the primary source are red to dark red in colour and more stable. The longer the sands remain in the aeolian (windblown) environment, the redder they become as a result of oxidisation and the release of iron oxide from within the small clay fraction in the sands. The lighter the colour sand dunes support less vegetation because of their instability and lack of nutrients.

Plantation Sandhills 

Gibber plains

 the hard country

Gibber plains - or as the locals say, the "hard country" - are stretches of country covered in small polished rocks, mainly of black and red hues, or pebbles called gibbers. These are polished fragments of the original duricrust (a layer of silica formed by the deposition of silca, iron oxides or calcium carbonate) that capped the plain some 65 million years ago. Fine abrasive material has swept past, wearing them down and rounding them off during rain and wind scour.

Today, they remain as a surface lag, protecting the underlying soils from water and wind erosion. You really need to get out of your vehicle and pick up a few to appreciate their smoothness and the intesity of their wonderful colours. Gibber plains are common along the Oodnadatta Track.  Allandale Station  features some excellent examples of Gibber Plains. Just north of Algebuckina (southern water tributory of The Neales River) where the gibbers are black rather than red-brown, the colour being derived from the type of iron mineral (goethite) they contain.

Tablelands and mesas

The stony  tablelands and isolated mesas found on the plains are the remanents of an ancient plain and indicate its original level.

Salt lakes and claypans

If you you have the opportunity to walk to the top of the mesa, you will gain understanding from the view over the dunes and see how they are seperated by flat areas called swales. Some of these are covered by gibbers. Others contain salt pans  or clay pans.

Claypans fill with water following rains, providing fresh water and often the right habitat for swamp canegrass. Swamp Canegrass (Eragrostis australascia) grows in low-lying areas that fill after good rains. It is very hardy and survives long periods of dry conditions as well as long periods of standing in water. Early settlers used the canegrass to line meat houses, vegetable gardens and for thatching on other buildings. It can grow in dense stands over large areas providing protection and habitat for many water bird species.

Information Courtesy of

Arid Areas Catchement Water Board

Government of South Australia

South Australian Tourism Commission