Bioregions of the nt
Kerle, J. A.
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Technical Report LRD94100 Viewed at 07:02:32 on 18/02/2010 Page 10 of 275. FINKE(FIN) The Finke River system is the major draiilage of the southern portion of Central Australia. Most other river systems are short-lived quickly disappearing into the sandy deserts. For most of the time it is a wide sandy river bed with many waterholes but in flood it reaches immense and terrifYing proportions. Throughout history it has been an extremely important route for travellers - Aboriginal and European - and pastoral activities began on the floodplains and grassy mulga plains very early in the settlement of Central Australia. There has been little survey of the biota of the region. Location imd Area This bioregion encompasses the present drainage basin of the Finke River, excluding its headwaters which are part of the MacDonneII Ranges bioregion (75,157 km2). It occupies the southern central portion of the N.T. from 24S - 26S to 131 "30'E - 135E (55,705 km2, 74%) and extends into South Australia. Climate . The region lies on the 200mm isohyet with the southern portion adjacent.to the Simpson Desert being drier 200mm). ErIdunda Station, near the centre of the region has an average armual rainfall of 194mm for the period 1933-1985. In the northern part of the region, adjacent to the MacDonnell Ranges, average rainfall is probably closer to 300mm. Like the rest of the arid centre, rainfall occurs predominantly in Surnnler but is extremely unpredictable in time and space. Maximum temperatures are generally high although the diurnal and seasonal range is large. MeanSurnnler temperatures range from 35C maxima to ? C minima and in winter from ?OC to 4C. Frosts can occur from May to August. Relative humidity ranges from 26% in November to 57% in June. The potential evaporation rate is 3,000 mmlyear. Geology, Topography and soils The Finke bioregion encompasses the eastern end of the Amadeus Basin where sandstones are ilie predominant underlying formation. Throughout much of the area these are covered by more recent deposits of alluvium, conglomerate, sand and travertine. The Musgrave Marm metamorphics intrude into the south-western corner around Kulgera, adjacent to the Central Ranges bioregion. The region is traversed by two major drainage systems. The Finke River, the longest river in Central Australia, runs from the north west to the south east and is joined by two major tributaries; the Palmer and Hugh Rivers. This river began cutting its way tlrrough the sediments ofilieAmadeus Basin some 15 million years ago and has previously drained into Lake Eyre. It now disperses into the sandplains of northern South Australia. The HenburylErldunda plains lie along the Finke River between the sand .plains and sand dunes of the Simpson and Western Deserts. While the hills across this plain are generally subdued, there are some remnants where the tertiary duricrust and siIcrete cappings have persisted. These include features like Chambers Pillar and Rainbow Valley. The line of Salt Lakes in the Lake Amadeus system continues through the Finke Bioregion, as Karinga Creek, the second major drainage system of the bioregion. This has, at times tlu'ough Bioregions of the NT DRAFT Version 3 7 Printed:March 25. 1996