AT THE POINT
Location: This confluence point is located in western Queensland, in the Gowan Range. Due to the nature of the terrain and thick vegetation, the exact confluence was not reached, and instead data was taken at a site approximately 1.5 km to the north-east (24°59'S, 145°01'E). The closest named feature to the actual confluence point is Mt Mistake, about 2 km to the north-west, after which the square is named. The site was visited in the early afternoon by a party of RGSQ members travelling in 4WD vehicles from Brisbane in November 2009. The closest settlement is Emmet, approximately 65 km to the north-west. The point falls just within the Blackall Tambo Regional Council area.
The Landscape: Elevation at the substitute site is 425 m ASL, and located on the western side of a sandstone and ironstone ridge. At the point the elevation is about 400 m ASL. The surrounding countryside is generally flat, with isolated outcrops of higher elevation. The surface at the site is bare sand and stones, and vegetation is primarily dense trees (heights 4-5 m). The underlying geology is sandstone of the Winton Formation which is from the Alban age (100 million years).
There were no animals at the site, although cattle of the properties and evidence of wild pigs were seen nearby. Aside from property infrastructure, significant human features include a power line, which is causing erosion where trees have been cleared. There is also an old survey marker near the summit of Mount Calder, approximately 7.5 km north-east of the confluence.
Mt Calder survey mark (Paul Feeney, 2009)
As seen in the Google Earth image above, a tributary of Wooroolah Creek is the closest watercourse to the confluence, and is a significant source of drainage for the area. It eventually flows into the Barcoo River and Cooper Creek sections of the Lake Eyre Basin.
Point information and photos: Paul Feeney with additions by Jo Grant, 2009
WITHIN THE DEGREE SQUARE
The Country: The landscape of the square is dominated by the hills of the Grey and Gowan Ranges which form the watershed between the Barcoo and Bulloo River catchments. These hills range in elevation between 350 and 450 m ASL. The geology of the Grey Range is composed of sandstone of the Glendower Formation which originated in the Late Palaeocene (55 million years). This material is eroded into steep sided escarpments and flat-topped ridges and mesas. The topography of the Gowan Range is similar but is largely composed of older sandstone of the Winton Formation which has its origin in the Albian period (100 million years).
Vegetation across the square appears to be a mixture of grassland and mulga woodland. Riparian communities along the drainage channels are dominated by Coolibah and River Red Gum. Wildlife is prolific, especially birdlife. Several rare or endangered species of macropod are also found in the area. For example, the Bridled Nailtail Wallaby (or Flashjack) is now found only within the Idalia National Park which sits across the Grey and Gowan Ranges. This area is also home to the yellow-footed Rock Wallaby. Red and Grey Kangaroos are also common across the square.
Drainage channels to the north of the square flow to the Barcoo River; those to the south flow to the Bulloo River. Both catchments form part of the Lake Eyre Basin.
MORE INFORMATION AND PHOTOS WELCOME
The Climate: The climate of the area is classified as persistently dry grassland. The Bureau of Meteorology climate station at Blackall provides representative statistics.
Blackall Township (036143) 1880-2010 (elevation 284 m ASL)
The highest temperature ever recorded in Blackall was 44.6oC in December 1979 and January 1990 while the lowest temperature was -2.0oC in July 1966. Rainfalls also vary greatly. The highest total of 1295.9 mm was recorded in 1890 and the lowest total of 185.1 mm in 1926.
Extremes of Nature: In spite of its inland location this area is exposed to the impact of tropical cyclones. The national cyclone database maintained by the Bureau of Meteorology contains eight cyclones that have passed within 200 km of the confluence point in the 101 years between 1906 and 2006. Of these, only one cyclone - TC Althea in December 1971 - came to within 50 km. Even distant cyclones can bring with them destructive winds and torrential rain that will lead to flooding in all streams.
Cyclone tracks within 200 km of point 1906 to 2006 (Bureau of Meteorology web site)
The area receives between 20 and 25 thunder days on average each year. The more severe thunderstorms can produce destructive winds, intense rainfall that may cause localised flash flooding, and lightning strikes may spark bushfires if there is sufficient fuel for it to spread.
Being at the headwaters of both the Barcoo and Bulloo Rivers, flooding is not a major issue, except locally and within the floodplains of the various streams. Some rapid stream rises can be experienced with the risk of loss of stock and other property if warning times are short.
Drought and heatwave remain the most frequent and severe natural hazards. Blackall averages 95 days a year with temperatures of 35oC or more and 11 days a year with temperatures of 40oC or greater. Heatwaves kill more people in Australia than all other natural hazards combined.
The National Earthquake Database maintained by Geoscience Australia contains no event epicentres within the degree square.
The Indigenous Story: The land within the square is the traditional country of the Kuungkari people to the north of the Gowan Range and the Dharawala people to the south.
MORE INFORMATION WELCOME
European Exploration and Settlement: Edmund Kennedy was probably the first European to sight this area when he passed to the north in 1847 and again in the following year. Graziers with their flocks of sheep probably entered the area by 1860.
Old Mt Calder Station (Paul Feeney, 2009)
MORE INFORMATION WELCOME
The total population of the degree square at the 2011 national Census was probably less than 50.
Sheep and cattle grazing is the dominant land use.
There are 1075 km of public roads within the square as well as many kilometres of private roads on the many properties in the square. Many of the properties also have their own airstrips. A section of the Yaraka rail link also passes through the north-west corner of the square.
Idalia National Park of 1.44 million hectares lies completely within the square. About two-thirds of the square falls within Blackall Tambo regional Council and one-third is within Quilpie Shire.
Compiler: Ken Granger, 2010
Edited by: Hayley Freemantle
References: various web sites including EPA, local governments, tourist industry and Bureau of Meteorology.
Queensland Museum, 2003: Discovery guide to outback Queensland, Queensland Museum, Brisbane.