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Sturt National Park and Tibooburra Dome banner

Granite Tors viewed from the lookout just north of Tibooburra
A quartz gibber plain in the Tibooburra region
A sand dune stabilised by vegetation
The road to Camerons Corner crosses a clay pan
This low range is known as a 'Jump-Up' which is a local term for silcrete capped mesas, cuestas (asymmetrical ridges) and ranges
Typical red sands of the Tibooburra region

Sturt National Park and Tibooburra Dome

Latitude -29.188474, Longitude 141.725599

Located in the Outback Region of NSW, nearest town Tibooburra

Source: www.environment.nsw.gov.au/resources/parks/pomfinalsturt.pdf

Source: http://brovey.yolasite.com/resources/Tib_inlier_tour.pdf

Link to Detailed Map

Sturt National Park was the setting for some of the most important events in the history of the early exploration of inland Australia. Charles Sturt, after whom the park is named, is one of the most prominent of the early explorers of Australia. He traversed large sections of the land (now reserved as National Park) as part of his exploration of what is now the Simpson Desert to the north and west. Cameron Corner is also of historical and social interest: it is the point where the boundaries of NSW, Queensland and South Australia meet and where surveyor John Cameron placed a marker in 1880.

Sturt National Park holds special significance for the local Aboriginal people due to the large number and variety of Aboriginal sites within it, including hearths, middens, ceremonial sites, quarries and abundant stone artefacts. Should you come across such objects they are protected by law so please leave them as you found them.

Sturt National Park covers a large area of the arid northwest corner of New South Wales. It comprises a range of landforms including gibber or Mitchell grass plain (depending on the weather), the Grey Range or 'Jump Up' country, the granite hills near Tibooburra, the stabilised red sand dunes of the Strezlecki Desert and riverine woodlands.

Tibooburra Dome

Tibooburra Dome is a broad physiographic and geological feature which developed roughly concentrically about the Tibooburra inlier. The Cambrian metamorphic rocks and Silurian granodioritic rocks which comprise the Tibooburra inlier are described in the Tibooburra inlier tour (source below) and occur as ridges and hills about Tibooburra village. As the name implies, the Tibooburra dome is a raised area of rocks in a general dome formation. This dome formed as a result of the slow upward rise of the relatively dense Cambrian rocks in the Tibooburra area. These rocks have arched upward due to pressure from the large volumes of relatively light Silurian granodiorite bodies within them. This process is much like rising air bubbles in a thick liquid where the air attempts to move upward because of the large contrast in density. This is a common phenomenon in geology, with trapped bodies of low density rocks being forced towards the earth's surface by surrounding high density rocks. As the high density metamorphic rocks can't simply move apart to allow the deeply buried granodiorite body to migrate upward, the rocks arch and fracture.

For a detailed tour exposing the geological evidence relating to the dome, log onto Bob and Nancys Geological Tour site http://brovey.yolasite.com/resources/Tib_inlier_tour.pdf.

Geology

The arid climate of Sturt National Park has resulted in distinctive landforms. The Tibooburra Downs land system includes the 'Jump Up', rolling downs/gibber plains/Mitchell grass downs and the 'Granites', and the 'North-West Sands' land system including the red dunes, sand plains, and ephemeral creek lines

The Jump-Up is a local term for silcrete capped mesas, cuestas (asymmetrical ridges) and ranges. They form a continuous bluff-type landform dissected by deep gullies, and include the Mount Wood hills and the southern end of the Grey Ranges which run north into Queensland.

The Rolling Downs slope away from the base of the Jump-Up. The higher rises are covered with the stony debris or gibber of the silcrete crusts. These gibbers are weather-worn pebbles of silcrete and quartz, mostly coated with a desert varnish which gives them a very polished appearance. The gibbers appear as bare sections amongst the Mitchell grass.

The Granites are low hills of granite tors around Tibooburra. They are the exposed centre of the Tibooburra dome, a granite batholith, and are the oldest rock formations in the park, dating back to the Silurian age (450-400 million years ago).

The western section of the park is dominated by sand plains and red dunes averaging 10-15 m in height. The red sand was blown in from the Strezlecki Desert during an arid period in the late Pleistocene. The dunes are now vegetated and immobile. Associated features are playas or small lakes with internal drainage, clay pans and lake basins.

The major watercourse in the park is Twelve Mile Creek which drains the eastern half of the park and runs out through Mount Wood Gorge. It has several natural waterholes which only dry out in extremely arid years.

In the western half of the park, drainage lines end in terminal basins. The largest creek is Fromes Creek which drains into Fromes Swamp and then Fort Grey basin (Lake Pinaroo). The basins flood during wet seasons and may hold water for several years.

Erosion is a natural feature of this arid environment. Local intense rain causes considerable erosion and downstream deposition of silt. Isolated areas of gullying and water sheeting may develop on steeper slopes. Some scalding (the process whereby large areas of topsoil are exposed due to the removal of vegetation) and wind sheeting has occurred on sandy areas.

The Rolling Downs Group

The park is located within the Great Australian Basin (formally known as the Great Artesian Basin) structural unit of eastern Australia. Sturt National Park contains extensive exposures of the Cretaceous Rolling Downs Group which are an important part of the basin. The Great Australian Basin was tapped earlier this century for water. Two formerly artesian bores, Narcowla and South Torrens, and several shallow bores remain in the park. Most bores were associated with ground tanks which also caught surface runoff.

An interesting feature closely associated with the Rolling Downs Group is the occurrence of cappings of silicified duricrust on outcrops of early Tertiary sedimentary rocks. These cappings result from soil forming processes during the latter half of the Tertiary Period when extensive parts of Australia were subjected to alternating tropical wet and dry seasons. This fossil soil capping gives rise to the distinctive mesa landscape of the Jump-Up country in North-Western NSW.

Boreholes in the Rolling Downs Group have revealed 'grey billie' or silcrete formation at depths of up to 60m suggesting that the tropical wet and dry seasons in the Tertiary Period extended back in time to the Cretaceous Period when the Great Australian Basin was being laid down. This area also has a very high density of watercourses, indicating previously wetter climatic periods in the last few thousand years.

Rainbow Rocks and the Olive Downs Polygons

Two interesting geological formations occur in the park; Rainbow Rocks and the Olive Downs Polygons. Rainbow Rocks is a striated sandstone outcrop with varied colours and patterns that give the protrusion its name. The Olive Downs Polygons are silcrete pipes and are a striking feature as they jut out from the silcrete capped Jump-Up. The park is also notable for the occurrence of tektites or small glassy rock fragments, presumably of meteoric origin.

Getting There

Sturt National Park is situated in the far north west corner of NSW about 350km north of Broken Hill. It extends to the north, east and west of the village of Tibooburra (population 170) and is bounded by the Queensland border to the north and the South Australian border to the west. Tibooburra is accessed by the Silver City Highway from Broken Hill (unsealed in parts). Take reasonable precautions when travelling in this region: report to National Parks in Tibooburra when driving into remote areas and advise when you will return and when you get back. Take plenty of food, fuel, spare tyres and water with you. Do not leave your car in the event of a breakdown. The weather is changeable and can go from extreme heat in the day to freezing at night, so make sure you have appropriate clothing. Ensure you leave gates in the same way you found them; for example, if you have to open a gate make sure you shut it when you pass through. If the gate is open when you get there, leave it open - it may be the only access animals have to water.

There is an interesting article on the Tibooburra-Milparinka Inliers located at this link www.crcleme.org.au/Pubs/guides/thomson/thomson_field_guide.pdf


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