About Carnarvon Gorge
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, which winds for over 30 kilometres (19 mi), 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.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 explaining why Carnarvon Gorge supports such a diversity of life.
[Wikipedia]
Cache
To claim this cache you must send me the answers via Email (prefered if you wanna get a quick response). After your mail you can log this cache straight away.
Boolimba Bluff Lookout:
1. How old are the puddle hollows you are standing on?
2. How many steps leading directly to and from the lookout?
The Roof Of Queensland:
3.How many mountains radiate from the Great Dividing Range?
4. (optional) We would appreciate a photo of you and the gorge in your log.
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