AT THE POINT
Location: This confluence point is located on the northern slopes of Mt Playfair on Mt Playfair Station within the Blackall Tambo Regional local government area. The nearest settlement is Tambo, about 75km to the west. The site was accessed via station tracks with the final 1100m to the exact point being travelled on foot.
The Landscape: The local landscape at the point is undulation with the point itself at an elevation of 610m ASL on the headwaters of the Nogoa River which is part of the Fitzroy River catchment. The local geology is sandstone of Middle Jurassic age (around 170 million years) which gives rise to a grey clay loam.
Collectors: J and M Nowill
Photos and information: John and Mary Nowill August 2011 with additions by Ken Granger
IN THE DEGREE SQUARE
Vegetation around the point is pulled Brigalow scrub with remnant trees including Poplar Box, Cyprus Pine and Bottle Trees.
The Country: The square straddles the summit of the Great Dividing Range with streams in the north-east such as the Nogoa River flowing to the Fitzroy River catchment and streams on the south and south-west such as the Warrego and Nive Rivers flowing to the Condamine section of the Murray-Darling system. Elevations range from 807m ASL at the summit of Mt King down to 300m ASL along the Nogoa River and 350m along the Warrego River. Topography in the square ranges from the very rugged and dissected sandstone country with cliffs of more than 100m in the Carnarvon National Park section to wide undulating land along the Warrego and Nive floodplains.
The oldest geology in the square is on the northern slopes of the Great Dividing Range where sandstone of Middle Triassic age (245 to 228 million years) dominate. On the crest of the Range and on its south-western slopes are younger sandstones of Early to Middle Jurassic age (200 to 161 million years). The foothills and slopes to the south-west are made up largely of sand plains of Cainozoic age (less than 66 million years). The higher country of Mt King is of volcanic origin with basalt of Cainozoic origin.
The vegetation of the square ranges from the eucalypt woodlands along the Range and open forest of the north-east slopes to pasture in the settled areas of the south-west.
The Climate: The climate of the area is classified as subtropical with a dry winter. The Bureau of meteorology climate station at Tambo Post Office, 75km to the west, provides representative statistics.
Tambo Post Office (035069) 1877 to 2009 (elevation 395 m ASL)
The highest temperature ever recorded at Tambo Post Office was 44.2oC in January 1973 while the lowest temperature was -5.6oC in July 1979 and August 1995. Rainfalls also vary greatly. The highest total of 1358.6 mm was recorded in 1890 and the lowest total of 206.5 mm in 1915.
Temperatures on the higher parts of the square are likely to be lower than at Tambo and rainfall on the north-east slopes are likely to be higher than at Tambo.
Extremes of Nature: Since 1906 a total of eight cyclones have passed within 200 km of the confluence point. Of these two came within 50 km of the point. They were an unnamed cyclone in January 1911 and an unnamed cyclone in January 1950, both of which originated in the Gulf of Carpentaria. All cyclones can bring destructive winds and intense rainfall that can lead to extensive flooding.
Cyclone tracks within 200 km of point 1906 to 2006 (Bureau of Meteorology web site)
Flooding in the water courses in the degree square are common and can be dangerous in terms of their rapid rise and strong flow velocities.
The area can experience extreme heat throughout some of the year, with Tambo having an average, over 52 years of records, of 63 days annually with maximum temperatures equal to or over 35°C and 4 days with over 40oC. The hottest months are December to February, all of which experience on average over 10 days with temperatures equal to or over 35°C. Such extreme temperatures can cause heat stroke and death if appropriate measures are not taken such as avoiding strenuous physical effort, keeping as cool as possible and drinking lots of water. Heat waves kill more people in Australia than all other natural hazards combined. By contrast, Tambo also averages 34 days with temperatures of 2oC or less a year and 17 days at 0oC or less. The National Earthquake Database maintained by Geoscience Australia contains no earthquake epicentres within the degree square.
The Indigenous Story: The land within the square is the traditional country of the Dharawala people in the west and the Bidjara people in the east.
MORE INFORMATION IS WELCOME
European Exploration and Settlement: The first Europeans to pass through the area were those on the expedition led by Thomas Mitchell in 1846. Mitchell passed through the area now dedicated as the Salvator Rosa section of the Carnarvon National Park and established a base camp in that valley.
MORE INFORMATION WELCOME
The total population of the degree square at the 2011 national Census was probably less than 50. The steady decline in the population totals over the decade was probably due to the decline in the rural industries caused by the prolonged drought and changes to census boundaries.
The main land use across the square is cattle grazing. Nature conservation is also significant with about 1.5 million hectares on the Carnarvon National Park complex, including the Salvator Rosa section, located within the square. The square contains about 1000km of public roads including a section of the Landsborough Highway. There are also many kilometres of private station roads and tracks.
Compilers: Ken Granger 2011
References: various web sites including EPA, local governments, tourist industry and Bureau of Meteorology.
Edited by: Hayley Freemantle