Carnarvon Gorge

Carnarvon Gorge is located in the Southern Brigalow Belt bioregion in Central Queensland (Australia), 593 km northwest of Brisbane. Around 30 kilometres long, and six hundred metres deep, Carnarvon Gorge is the most visited feature within Carnarvon National Park due to the diversity of experiences it contains and the ease with which it can be accessed. The closest towns are Injune and Rolleston.

History

Aboriginal people didn't live in the gorge, only nearby, as the gorge was considered sacred. [Whelan, Howard. (1996). "Touching the Spirit". in Australian Geographic #41. pp. 34 - 57. Australian Geographic Society.] The dreamtime stories tell a tale of the Rainbow Serpent which made the gorges.

Ludwig Leichhardt was the first European explorer to pass nearby and make note of the ranges.

Features

Within the lower ten kilometres of the Gorge, visitors can encounter a variety of cultural and natural values that, elsewhere in the region, would require considerable travel to experience; significant Indigenous cultural sites and rock art sites, narrow sandstone canyons, extensive sandstone cliff lines, basalt-capped tablelands and mountain ranges, and relict rainforest vegetation.

There is a ten kilometre (10km) extensive system of walking and longer hiking tracks along the gorge, including to places such as the Art Gallery and the Big Bend a huge basalt dike, Wards Canyon, Cathedral Cave, the Amphitheatre and the beautiful Moss Garden.

Rocks and Landscapes

Situated within the Central Queensland Sandstone Belt, and separating the Consuelo Tableland and the Great Dividing Range, Carnarvon Gorge's landscapes have largely been shaped by water erosion. Over the last twenty seven million years Carnarvon Creek has carved down through six hundred metres of stone, exposing rocks from three significant phases of Queensland's geological history including two sedimentary basins, the Bowen and the Surat, and the Buckland Volcanic Province. The youngest rocks in the area are the igneous basalt rocks of the Buckland volcanic Province which were laid down between 35-27 million years ago to depths of up to 300 metres [Walsh, G. L. 1999. "Carnarvon and Beyond" p 27. Takarakka Nowan Kas Publications.] . The basalt layer is present on top of the high country either side of the Gorge where it protects the landscape from erosion and generates significantly different soils to those derived from the lower sedimentary rocks. Boulders eroded from the basalt layer dominate the Gorge's waterways due to their ability to resist water erosion better than the sedimentary rocks they once overlaid.

The most visible rocks in the Gorge belong to the Surat Basin, which holds most of Queensland's gas and oil and significant amounts of groundwater. The Surat Basin forms part of the Great Artesian Basin, and generates numerous springs within the Gorge. The oldest component in the Surat Basin is the porous Precipice Sandstone, which forms the Gorge's spectacular cliffs. The Precipice Sandstone is one of the primary intake beds for the Great Artesian Basin, giving the area where it lies exposed significance as a replenishment zone.

Below the Precipice Sandstone, the Gorge's floor is formed by the uppermost layer of the Bowen Basin, the Moolayember Formation. The impermeability of this layer allows the water generated by Carnarvon Gorge's springs to remain close to, or above, the surface - a significant interplay in terms of the availability of water within the Gorge's ecosystems. Carnarvon Creek, whose flow has only been known to stop twice since records commenced, is an incredibly reliable source of water. In times of drought, it turns the Gorge into an oasis which has supported forms of life long since passed from the semi-arid ecosystems surrounding it.

Each of the rock strata exposed in the Gorge erodes and weathers according to its own characteristics, and the variety of soil types and landforms generated goes a long way towards explainng why Carnarvon Gorge supports such a diversity of life.

Climate

Carnarvon Gorge's climate is considerably different to that experienced in the flatter terrain surrounding it. Average rainfall in the Gorge is higher at 1,000 millimetres per annum and temperatures on the Gorge floor are more moderate. The lowest temperature recorded in the Gorge is -2ºC, whereas temperatures lower than -5ºC are experienced within 5 kilometres of its mouth. Average July temperature range is 6.3ºC-20.9ºC, and average January temperature range is 20.5ºC-35.5ºC. Statistically, the wettest month is February and the driest is August.

These figures should always be considered in the context of Australia's notoriously unpredictable climate. For example, between October, 2007, and February, 2008, Carnarvon Gorge received 1,400 millimetres of rainfall; 140% of its annual average.

Flora

Three broad vegetation types are present in Carnarvon_Gorge; eucalypt and angophora dominated woodland to open woodland; mixed eucalypt, acacia, white cypress pine or turpentine woodlands and/or open forests on sandstone slopes, scarps, ridges and residuals; cleared and/or regrowth areas [Grant, Claire. 2005. "Carnarvon Gorge - Management Plan" pp 6-9. Environmental Protection Agency, Queensland.] . Four regional ecosystems listed as of concern are easily encountered by visitors to Carnarvon Gorge; Queensland blue gum woodland on alluvial plains; silver-leaved ironbark woodland on alluvial plains;, Queensland blue gum, river she-oak fringng woodland on alluvial plains. tall open forest in sheltered gorges and moist habitats.

Two plant species, in particular, are considered Carnarvon Gorge icons; the cycad "Macrozamia moorei" (no common name) and the Carnarvon fan palm ("Livistona nitida"). "Macrozamia moorei" is closely associated with the Tertiary basalt flows of the Buckland Volcanic Province, and is endemic to Central Queensland. "Livistona nitida" is endemic to the springs and waterways of the Dawson River catchment, and Carnarvon Gorge is considered its stronghold.

Several plants occur in disjunct populations, or approach the limits of their distribution, within Carnarvon Gorge such as the isolated colony of king ferns ("Angiopteris evecta") found in Wards Canyon and the stately Sydney blue gum ("Eucalyptus saligna") found in the Gorge's wettest habitats.

Fauna

Mammals

Carnarvon Gorge has a rich mammalian fauna including Australia's two monotremes, the platypus ("Ornithorhyncus anatinus") and the echidna ("Tachyglossus aculeatus"). Macropod species include the eastern grey kangaroo ("Macropus giganteus"), the pretty-faced wallaby ("Macropus parryi"), the swamp wallaby ("Wallabia bicolor"), the wallaroo or euro ("Macropus robustus"), the red-necked wallaby, ("Macropus rufogriseus"), and the rufous bettong ("Aepyprymnus rufescens").

Five of Australia's six species of glider occur here; the greater glider ("Petauroides volans"), the yellow-bellied glider ("Petaurus australis"), the squirrel glider ("Petaurus norfolcensis"), the sugar glider ("Petaurus breviceps"), and the feathertail glider ("Acrobates pygmaeus"). Commercial spotlighting tours that target the Gorge's gliders are conducted within the Park. [Ling, Simon. 2000-2008. [http://www.ausnatureguides.com/Pages/CarnarvonGorgeNightlifeTour.html www.ausnatureguides.com/Pages/CarnarvonGorgeNightlifeTour.html] . Australian Nature Guides.]

Birds

Over 180 species of bird have been recorded within the Gorge, from the tiny weebill ("Smicrornis brevirostris") to the wedge-tailed eagle ("Aquila audax"). Some of the Gorge's birds have become habituated to humans, due to hand-feeding which is against Park regulations. This situation is of concern to Park rangers as it allows opportunistic species, such as the laughing kookaburra ("Dacelo novaeguineae") and the pied currawong ("Strepera graculina"), to develop population sizes that are abnormally large. When visitation (and therefore hand-feeding) tapers off over the summer low tourism season the abnormal populations place abnormal pressure on the species' natural food sources which can include the young of other bird species.

Australian bustards ("Ardeotis australis") are frequently seen in farmland on approach to the Gorge, along with brolgas if the weather has been wet. Communally breeding birds, such as the white-winged chough, the laughing kookaburra ("Dacelo novaeguineae"), and the Apostlebird ("Struthidea cinerea"), are a feature of the ecosystems around the entrance to Carnarvon Gorge.

Peregrine falcons ("Falco peregrinus") and wedge-tailed eagles patrol the cliffs further into the Gorge whilst, below, numerous parrots and honeyeaters forage amongst the eucalypt canopy. Closer to ground level, visitors are likely to enounter the Australian raven ("Corvus coronoides") and the pied currawong ("Strepera graculina") anywhere they stop to eat. Along the walking tracks many smaller species will be present in the ground cover and understory including red-browed finches ("Neochmia temporalis"), white-browed scrubwrens ("Sericornis frontalis"), and several species of thornbill.

Footnotes

ee also

*Bunya Mountains

References

*Grant, Claire. 2005. "Carnarvon Gorge - Management Plan". Environmental Protection Agency, Queensland.
*Beeston, J.W. & Grey, A.R.G. 1993. The Ancient Rocks of Carnarvon Gorge. Department of Minerals and Energy, Queensland.
*Ling, Simon. 2000-2008. [http://www.ausnatureguides.com www.ausnatureguides.com] . Australian Nature Guides.
*Walsh, G.L. 1983. The Roof of Queensland. Queensland University Press.
*Walsh, G. L. 1999. Carnarvon and Beyond. Takarakka Nowan Kas Publications.
*Warner, C. 1987. Exploring Queensland’s Central Highlands. Charles Warner.