GEOGRAPHIC EXTREMES SOCIETY
AUSTRALIAN RECORDS
Monoliths
There are many claims to the title of Australia’s largest Monolith. Mount Augustus to the west of Carnarvon in central Western Australia, often claims to be the world’s largest rock. Quite a deal of literature cites claims to the fact that Mount Augustus is twice as large as Uluru, which is true, but is this mountain in central Western Australia a monolith?
Geologists usually try to avoid using the term monolith because the meaning can be quite ambiguous. For some, a monolith can be a single mountain standing alone, on the other end of the scale, others consider it to be a large unfractured rock. So, for our purposes and to avoid confusion, the Geographical Extremes Society have set the definition of a monolith as being thus:
- a single rock body consisting of the same geological material
- free-standing and rising prominently above the surrounding landscape
- almost entirely devoid of vegetation
- covered by very little or no soils clinging to the exterior of the rock surface
- measurable by the part of the rock rising above the surface of the landscape
With these criteria in mind, the claim for Mount Augustus to being the world’s largest monolith is void. Mount Augustus has a vibrant covering of vegetation, is made from a stratified assortment of different rock types, and has a lot of soil on the surface. Luckily for us, there are plenty more big rocks in Australia to explore.
Mount Augustus. Image supplied by Western Australia Parks and Wildlife Service
The next contender is Mount Wudinna, just off the Eyre Highway in South Australia. There are claims that this granite outcrop is the world’s second-largest monolith after Mount Augustus. A visit to the carpark at the base of Mount Wudinna tones down the extravagant claim, with a sign stating that it is one of Australia’s largest granite monoliths. While it is a magnificent granite outcrop well worth a visit, the claim to being a monolith adjudged by our criteria fails, due to vegetation covering a large section of Mount Wudinna.
Mount Wudinna. Image supplied by Tourism South Australia
Let’s consider Bald Rock, on the border of New South Wales and Queensland and not far from the historic township of Tenterfield. Those who champion the Bald Rock case describe it as being the largest exposed granite monolith in Australia. It does have quite an impressive large exposed granite surface, but once again there is plenty of vegetation covering large portions of the rock. The image below shows the best face of Bald Rock
Bald Rock. Image supplied by Tenterfield Visitor centre
Uluru continues to stand out singularly, as the largest monolith in the world. This immense slab of sandstone personifies the country’s ‘Red Centre’, and happen-stance has it prominently located close to several central points of Australia.
Uluru. Image supplied by Northern Territory Tourism
Little vegetation or soils adorns Uluru, and it protrudes majestically above the landscape. Uluru is unusual in that massive monoliths are rarely formed from sedimentary rocks. Most monoliths are usually formed deep underground as intruded granitic lavas. Uluru’s sandstone emanated from ancient, long-vanished river systems originating from the once-massive Petermann Ranges. Uplifting of the Petermann Ranges took place approximately 600 million years ago when researchers believe parts of India rammed into Western Australia. The result was a slow-motion tectonic collision which raised these ranges to a height similar to today’s Himalayas [4]. The resulting rivers stripped sediment from the treeless mountains and quickly filled the large basins to the south. The nearby, and just as impressive Kata Tjuta formation, once known as the Olga’s, was situated closer to the Petermann Ranges and received coarser sediments, including large boulders now fused into the sandstone. The sands which formed the Uluru sediments were much finer and subject to greater pressure when submerged under ancient seas. Indeed, over 80% of this 550-million-year-old monolith is still buried underground in folded layers.
It’s believed that Kata Tjuta was once far larger than Uluru before weathering broke down the monolith into the many domes we recognise today. These domes are impressive, and in wandering around the footprint of Kata Tjuta, provides an insight into how immense this monolith once was.
GES Record: Largest Monolith in Australia & World – Uluru, Northern Territory.
The Geographic Extremes Society welcomes any input as to the veracity of these records and we encourage everyone to contribute to these extreme records by contacting us to initiate the discussion