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Uluru just the tip of the iceberg



Researchers from Monash University have explored the 550-million-year formation of an Indigenous sacred site – Uluru – in the Northern Territory. Their findings uncovered a history of mountain ranges, tectonic movement, an inland ocean and a supercontinent.

Originally published in The Conversation, lecturers Melanie Finch and Andrew Giles discussed what scientists have learned about the world’s largest monolith over the past 30 years.

“Around 550 million years ago, continents collided as part of the assembly of the supercontinent Gondwana, one of several times in Earth’s history where most of the continents were stuck together in one continuous piece of land,” Giles and Finch began.

This supercontinent saw significant stresses reverberate across Australia, as India rubbed shoulders with Western Australia, pushing tectonic plates together and forcing rock upon rock to rise above the landscape.

These earthquakes and movements caused what became known as the Petermann mountains which – at the height of their powers – would have stood hundreds of kilometres long and five kilometres high.

These mountains were mostly granite, according to the researchers, and had no vegetation to protect them from the elements as land plants hadn’t yet evolved.

“Bare mountains weather quickly because they are more exposed to rain and wind. Big cracks formed in the granite, splitting away rocks and boulders, which fell into rivers gushing down deep valleys carved into the mountain,” the researchers continued.

The sand from eroded mountains formed layers and layers of sandstone which weighed upon the ground beneath to form a basin and the perfect storm for an inland ocean.

“Sediment continued to deposit into the ocean until about 300 million years ago when the ancient faults began to reawaken during a new mountain-building event called the Alice Springs orogeny,” they wrote.

This next cycle of mountains birthed what would become known as Uluru, as the summit of one tectonic movement peaked above the landscape.

“If we could dig underneath Uluru, we would see it is only the very tip of a rock sequence that extends kilometres down under the surface, like a rock iceberg,” the researchers concluded.

“But even if we could, why would we want to? Uluru’s magic is most evident when you stand at its base, look up, and picture in your mind the enormous forces that conspired to form it.”

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