Uluru: The world’s largest monolith that changes colour with time
How big a rock can you imagine? We are talking about a single natural rock or a monolith, not a structure made of small rocks. Any guesswork? Well, let us tell you that the largest single rock monolith stands over 1000 feet high above the land and goes over 9 km around if you decided to walk it. It is famously called Uluru or Ayers rock and is located in central Australia.
Uluru at a glance
Uluru or Ayers Rock, the largest single-rock monolith in the world, is located in the southwestern northern territory of central Australia. Can you guess its height? Its stands a whopping 348 metre (1,142 feet) high above the surrounding desert plain. That is a height of 863 metres or 2,831 feet above the sea level. You would have to walk for 9.4 km to take one around the oval-shaped monolith because it is 3.6 km long and 2.4 km wide. That is not all. Uluru extends much more below the ground as much it is above. The monolith extends at least 2.5 km down into the ground.
Birth of Uluru
But how did such a grand natural structure form? The process started around 900 million years ago. At that time, this part of Australia was a shallow sea. Multiple layers of mineral-rich sandstone got laid down on the ocean floor. Then, about 550 million years ago, these sandstone layers which had hardened by that time, uplifted to form mountains. These mountains gradually eroded and washed away into a number of large sediment-rich alluvial fans. If you don’t know, an alluvial fan is a fan-shaped area formed by constant deposition of silt, sand, gravel, boulders, and woody debris by rivers and streams over a long period of time. One of these alluvial fans formed the basis of Uluru.
Some 500 million years ago, the area was again flooded by a shallow ocean, compressing and cementing Uluru's sandstone. The sea retracted between 400 and 300 million years ago and the rocks folded. After a long phase of erosion that lasted hundreds of millions of years, Uluru emerged from the softer rocks.
Discovery of Uluru
Though the rock has long been revered by the local aboriginal people, it was first sighted in 1872 by the European explorer Ernest Giles. It was paid its first visit the following year when surveyor William Gosse named it for Sir Henry Ayers, a former South Australian premier.
The monolith is located within Uluru–Kata Tjuta National Park and has been named a UNESCO World Heritage site. It originally belongs to the local aboriginal people, Anangu but they have leased it to the Australian government. World Heritage site. It originally belongs to the local aboriginal people, Anangu but they have leased it to the Australian government.
The colour changing stone
What is really interesting about Uluru is its striking colour. The rock is rich in iron minerals which have slowly rusted over the years giving it a bright red colour. Because of its reddish tint and its location, it is often called Australia’s “Red Centre.” Something even more intriguing is the fact that you can see Uluru in a different colour at different times of the day. But how is that? Well, as the sun changes its position, the rock appears to change colours, from red to orange to purple and back again. You will find it most visually striking at sunset when it turns fiery orange-red due to the sun’s rays.
No, it is not the world’s largest rock
So, is it the world’s largest rock? No, that title is credited to Mount Augustus in Western Australia. It is composed of multiple rock types so it is technically not a monolith but the world’s largest rock.