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More Just In. Gradual removal of the soft sand and clay has exposed the rounded boulders, allowing them to be perched on top of one other. According to Aboriginal dreaming, the rocks are sacred and are the fossilised eggs of the Rainbow Serpent. The visible portion of the sandstone and conglomerate structure which makes up Mount Augustus, is twice the size of Uluru. Sitting on a bedrock of granite, the mountain is eight kilometres long and stands metres above the surrounding plain and metres above sea level.
Sometimes described as the world's largest monocline, it is estimated that the rock of the mountain is around million years old and was formed from an uplift which raised an ancient seabed of sedimentary proterozoic sandstone and conglomerate. The granite rock which lies beneath Mount Augustus is said to be million years old.
The Indigenous name for Mount Augustus is Burringurah. Formed more than million years ago, Wave Rock is 14 metres high, and metres long. The granite cliff resembling a wave about to break is on the northern face of a large erosional remnant called Hyden Rock. This curved cliff face is 15 metres high and metres long which has been rounded by weathering and water erosion, undercutting its base and leaving a rounded overhang.
It was formed by water dissolving and re-depositing chemicals in the granite as it runs down the cliff face. The mountain is an isolated volcanic core rising metres above sea level near the historical villages of Tilba Tilba and Central Tilba. Viewed from the sea the mountain resembles a dromedary camel.
It was formed during volcanic activity which took place about million years ago. An inselberg, or isolated rock hill, Bald Rock is said to be Australia's largest exposed granite surface.
It towers about metres above the surrounding bushland, is metres long, metres wide and rises to metres above sea level. The weight of the new seabed turned the fans into rock.
The sandy fan became sandstone Ulu r u while the rocky fan became conglomerate rock Kata Tju t a. Kata Tju t a tilted slightly and Ulu r u tilted 90 degrees. Over the last million years, the softer rocks eroded away, leaving the spectacular forms of Ulu r u and Kata Tju t a behind. Ulu r u is a type of rock called arkose. If you take the base walk you can see that the surface is actually flaky red with grey patches.
The flakes are bits of rock left after water and oxygen have decayed minerals in the rock. Kata Tju t a is made from a conglomerate of pebbles and boulders cemented by sand and mud. Most of the pieces are granite and basalt, which give the conglomerate a plum-pudding effect. Darker greens indicate swaths of vegetation that thrive because of the many natural springs along the footslopes of the rock.
Farther away, desert scrub vegetation on the drier soils of the linear sand dunes has browner tones. Uluru and Kata Tjuta are remnants of sediments eroded from an ancient mountain range that existed about million years ago. The sediments were subsequently buried and compressed to form harder rocks—called arkose and conglomerate by geologists. These rocks were later tilted from their original horizontal orientation by powerful tectonic forces.
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