Australian rocks and mountains
Australia is a very flat continent where the average elevation is just 330 metres, the lowest in the world. What Australia lacks in height is more that made up for in the variety, geological age and unique appearance of its mountains and rocky outcrops - some of the oldest and most interesting exposed rocks in the world.
The highest point in Australia is Mount Kosciuszko (named by Sir Paul Edmund de Strzelecki in 1840 after the Polish patriot and democratic leader Tadeusz Kosciuszko) in New South Wales, at 2,228 metres above sea level. Mount Kosciuszko is part of the Great Dividing Range.
The Great Dividing Range
The Blue Mountains, New South Wales. Image courtesy of Tourism New South Wales
The Great Dividing Range is one of Australia's most important geographical features. It divides the east coast from the inland and has a major influence on our climate, population spread and settlement patterns, economics and agriculture. It is home to an amazing array of plants and animals that don't exist anywhere else on earth. It is the source of our longest rivers and our highest mountains.
The range runs parallel to the east cost of Australia, from Cape York in the North to Western Victoria in the south. Tasmania, Australia's island state which lies even further south, is also a part of this massive and ancient mountain range.
The Great Dividing Range has it origins many millions of years ago when the continents of earth were fused together as the Gondwana land mass. A huge uplift in the earth's crust occurred over millions of years, during the Pliocene and the Pleistocene Epochs (between 5.4 million to 10,000 years ago). This was just after the extinction of the dinosaurs and during the time that modern humans first appeared.
As the ranges eroded over millions of years, the high mountain tops became islands. Populations of animal species which used to live across large areas became concentrated on the mountains and groups became isolated from each other. Over many thousands of years, this isolation meant that species evolved independently and this led to many variations in species.
The ranges are also home to some amazing species of animals and plants that are survivors of Gondwana. The Wollemi Pine, recently found growing in a gorge of the Blue Mountains, is a living dinosaur of the plant world. Twenty-three of the 35 known species of the carab beetle live on just one mountain top in northern Queensland, at the top of the Great Dividing Range.
Other rock structures in Australia, like Uluru, Mount Augustus and Bald Rock, have been described as monoliths. However the term monolith, primarily used to describe buildings, is considered by geological experts to be inappropriate in describing these structures, as they do not meet the strict scientific geological criteria of it being made only of one stone and standing alone as demonstrated in the Sardires peak in the Vanoise massif of the Western French Alps.
Uluru, Northern Territory. Photo courtesy of GeoScience Australia
Uluru is located in the National Heritage Listed Uluru-Kata Tjuta National Park about 335km to the south-west of Alice Springs in Northern Territory, Australia. It is part of a massive rock feature that stretches underground for many kilometres, and is part of the Kata Tjuka (Olgas) outcrop.
Uluru is 9.4km around the base, and about 345 metres high (and is thought to be the tip of an old silt fan formation tilted up by geological movement, which extends kilometres below the surface). Above the ground it is 3.6km long, 2km wide, and is roughly oval in shape. It is made of sedimentary arkosic sandstone (less than 75% compressed lithified sand and more than 25% feldspar), and is renowned for the way it changes colour in the light and is particularly spectacular at sunrise and sunset.
The colonial explorer William Gosse, who visited the area in 1873, named the rock feature Ayers Rock after Henry Ayers, then Governor of South Australia.
Uluru was returned to the care and control the Pitjantjatjara and Yankunytjatjara people (also known as Anangu) in 1985 to whom it had been home for tens of thousands of years. In 1995 the name of the National Park was changed from Ayers Rock-Mount Olga National Park to Uluru-Kata Tjuta National Park to acknowledge Anangu control and their relationship with the area.
Mount Augustus, Western Australia. Photograph by Malcolm Wells.
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 stands 858 metres above the surrounding plain and 1105 metres above sea level and is eight kilometres long. It can be seen clearly from 160 kilometres away and is sometimes described as the world's largest monocline, part of Mount Augustus National Park.
It is estimated that the rock of the mountain is some 1000 million years old. It was formed from an uplift which raised an ancient seabed of sandstone conglomerate and folded it into a dramatic anticline (like an inverted V shape). The granite rock which lies beneath Mount Augustus is said to be 1650 million years old.
Francis Gregory, on his journey through the Gascoyne, became the first European to climb the mountain in 1858, and he named the rock after his brother, Sir Augustus Charles Gregory (1819-1905). It is called Burringurrah by local Wadjari people after a Dreamtime figure, a young boy, who was speared and turned into a rock.
More than 100 species of birds can be seen on and around Mount Augustus. There are also many watering holes near Mount Augustus. Like Uluru, the colour of the rock changes during dawn and dusk. Bright pink, orange and red with the occasional green reflect the changes of its mood. Unlike Uluru, there is a great deal of plant growth on and around the mountain, dominated by wattles, cassias and eremophilas.
Bald Rock. Photo used with permission from Henry Gold.
Bald Rock is situated in Bald Rock National Park on the New South Wales-Queensland border. The park is accessed via the Mt Lindesay Highway.
The ' Rock' is Australia's largest exposed granite surface, and rises to 1277 metres above sea level. It towers about 200 metres up out of the surrounding bushland, is 750 metres long and 500 metres wide.
Geography, geology and formation
- ABS Year Book - Mountain Systems of Australia
- Highest mountains - Geoscience Australia
- Significant rock features - Geoscience Australia
- Great Dividing Range - Wikipedia
- Taming the fire: the first wave 40,000 - 60,000 years ago
The Wollemi Pine
- Wollemi Pine - Australian National Botanic Gardens
Last updated: 18th June 2007
Creators: Mijo Consulting, Kathryn Wells