AT THE POINT
Location: Poeppel Corner is at the intersection of Qld, SA and NT, in sight of Lake Poeppel. The site is deep within the Simpson Desert., a vast region in which linear dunes are the main landscape feature. The point is found between Lake Poeppel (immediately to the west) and a linear dune that trends SSE-NNW (a little over half a kilometre to the east). Like Queensland's other borders, there is a discrepancy between the specified latitude or longitude and the officially mapped border (in this case, of several hundred metres).
The most commonly used access to the point from Queensland is the 4WD track running west from Birdsville (the QAA Line), then south to the confluence. The nearest settlement is Birdsville, Qld, about 135 km in a straight line to the East (and slightly north). The site was visited by a party of RGSQ members travelling in four 4WD vehicles from Brisbane in May, 2008.
Landscape: Degree Confluence 26°S 138°E is located on a gentle slope between a linear dune to the east (about half km distant) and a long (18km), narrow (up to 1km wide) salt lake (Lake Poeppel) to the west. The terrain slopes downwards to the west. The lakes and dunes adjacent to the point, and in the wider area trend, SSE - NNW. The dunes of the area have considerable portions of active sand, especially on the summit.
The ground surface is mostly bare of vegetation at both the confluence and the Corner. Scattered grass clumps, bushes and low trees are visible. The view looking west (NT in the NW, SA in the SW) is dominated by Lake Poeppel. The view looking east (Qld in the NE, SA in the SE) is made up of the gentle upwards slope to the nearby linear dune. At this site, land inside Queensland belongs to Simpson Desert NP, while South Australian land is part of Simpson Desert Conservation Park.
Geological features of the point include Quaternary (Pleistocene-Recent) Aeolian sand of orange-brown, fine to medium-grained quartz sand of sub-parallel longitudinal dunes of the desert, and the clayey sand of inter-dunal flats. There is also Quaternary (Pleistocene-Recent) fine, orange to brown, clay sands and grey silty clays containing halite (salt) and gypsum in salinas and claypans. The underlying formations are Cretaceous and Upper Jurassic sedimentaries.
Point Photo Credits: Paul Feeney, Mary Comer
Point Information By: Col & Jo Grant
IN THE DEGREE SQUARE
Climate: The closest representative weather station to the confluence is at the Birdsville Police Station. It has an elevation of 47m, and has been recording data since 1892.
The highest temperature recorded was 49.5°C in December 1972, and the lowest was -1.7°C in June and July 1965. The greatest rainfall recorded in a year was 541.8 mm in 1916, and the least was 33.2 mm in 1913. These and other climate statistics for Birdsville can be found at: Australian Bureau of Meteorology, http://www.bom.gov.au/climate/averages/tables/cw_038002_All.shtml
Extremes of Nature: Since 1906 there have been no cyclones to pass within 50 km of the degree confluence, and only 1 within 200 km (1976). Cyclone information for this area and all of Australia can be found at the Australian Bureau of Meteorology website, http://www.bom.gov.au/cgi-bin/silo/cyclones.cgi
Cyclone tracks within 200 km of the confluence, 1906 to 2006 (Bureau of Meteorology web site)
Extreme heat and drought are also serious issues. Records show that Birdsville experiences 113 days annually with temperatures over 35°C, 45 of which typically reach 40°C or warmer. 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. In addition, with very little rainfall and only 23 days a year on average with any rain, the area is also among the driest in Australia.
Today: The population of the degree square is certainly less than 10.
Geoscience Australia, NATMAP Raster
Geoscience Australia, Scanned 250 K Geology Maps
Edited by: Hayley Freemantle
More to come