A Dive into the Geological History of the Red Centre

With so many stunning rock formations and structures dotting the expanse of the Red Centre, have you ever wondered how they were formed? If you’ve ever been or plan on visiting, you’ll hear the fantastic stories of the Creation, the indigenous Dreamtime folklore about giant animals & characters whose adventures & interactions formed the world around them.

But there’s also the geological explanations for what made Uluru, Kings Canyon, and the MacDonnell Ranges, what they are made from and what they might be like in the future. Have a read below about some of Central Australia’s most significant geological marvels and find out for yourself why these formations are some of the most special in the world.

Uluru & Kata Tjuta 

Uluru stands around 863m tall, 3.6km long, 1.9km wide, extends an estimated 2.5km underground and it’s made entirely of sandstone. More impressive than its position as a lone monolith in the middle of the desert is that its formation started somewhere between 400-500 million years ago! Because Uluru is made of arkose sandstone (a special type which is very high in iron), it’s color changes over time and even through the day in different lighting it will appear to vary greatly in its bright shades of red.

Nearby Uluru, Kata Tjuta (a formation of 36 dome shaped rocks) rises at its highest to 546m above the ground. But unlike Uluru, Kata Tjuta covers an area of 21.68 square kilometers and is made of a combination of cobbles, boulders, granite, basalt and many others all cemented together by sandstone. The interesting part is that both of these sites were once entirely covered by water and started forming at the same time. Shifts in tectonic plates and erosion over millions of years have left them to stand as they are today. 

Lake Amadeus

The salty plain known as Lake Amadeus is 180km long and 10km wide and contains within it over 600 million tonnes of salt! The lake itself is presumed to have been created following the Petermann Orogeny - a massive geological event which caused tectonic plates to lift and fold over each other around 550 million years ago.

The lake itself is within a basin filled with erosion material from this event which has been incredibly helpful to geologists in understanding its past. Unfortunately though, due to its very remote location, there haven’t ever been any successful attempts to harvest any salt!

Henbury Meteorites

Unlike the name would suggest, the Henbury Meteorites Reserve is actually better viewed for the craters caused by the meteorites’ impact rather than the meteors themselves. The craters were formed some 4,000-5,000 years ago when enormous rock meteors collided with the earth traveling at around 40,000kph. The meteor remains are found strewn throughout the area of the 12 craters, and so far over 500kg of metal have been found within them consisting mostly of iron and nickel. 

Tnorala (Gosse Bluff)

Similar to the Henbury Meteorite site, Tnorala is home to an enormous crater roughly 20km wide which scientists believe was created when an enormous meteor collided with the earth some 143 million years ago. It’s believed that the comet which made impact was around 600m across though you may not guess it by viewing today. Over time erosion has caused the impact site to become smaller and less dramatic.

Kings Canyon

The famous Kings Canyon dates back to beyond 440 million years ago when its lower levels of Carmichael sandstone were first deposited. It’s estimated by geologists that around 40 million years after this, the valley started to form by carving through a softer layer of sandstone above. The formation now beholds cliffs over 100-150m tall and extravagant gullies and rock carvings all created through millions of years of water, wind and sand erosion. 

MacDonnell Ranges

Some estimates suggest that the 500km stretch of the MacDonnell Ranges started to form 1,000 million years ago, with the components of rock within them dating back nearly 2,400 million years ago. It’s estimated that the ranges themselves were formed (or started forming) at a ‘folding event’, a phenomenon whereby two or more tectonic plates are pushed together and the meeting points in the middle are pushed upward. The Ranges were originally over 4,500m high but today stand at only 400-500m due to years and years of erosion.

Corroboree Rock

This dark grey/black structure of dolomite sticking out from the ground was formed around 800 million years ago. The site is incredibly sacred to the local indigenous population, though its geological history is almost as interesting.

In simple terms it is the remains of a deposit of dolomite left during the Bitter Springs Formation when the area was all salty lakes. The soft dolomite rock today is the eroded remainders with its base being a speckled collection of grays as the different dolomite types have weathered over the years.  

Rainbow Valley

Part of the James Range, Rainbow Valley is culturally significant as it’s home to a host of aboriginal artwork and landmarks which feature in indigenous storytelling. But the sandstone cliffs, gullies and juts are interesting in their geology too.

The rich colours on display (which change through the day at different levels of sunlight) come from years and years of water erosion. Millions of years ago when the area was far wetter, red sandstone was dissolved and only surfaced again during drought. But since this stone is much harder than white sandstone, over time, the whiter sandstone has eroded and fallen away like dust, leaving a diverse palette of sandstone colours now visible in the cliff faces, giving it its name.

Chambers Pillar

Serving as an historic landmark guiding explorers in the early years of Australia’s discovery and settlement, Chambers Pillar is a sandstone column reaching over 50m above the desert floor. It’s estimated that the pillar first started forming around 350 million years ago following sandstone deposits being eroded by wind and rain. The pillar now stands very isolated against the desert skyline and is eerie in its towering posture over the land.

Devils Marbles

Unlike a lot of the other rock formations in the area coming from tectonic shifts, the Devils Marbles were formed by cooling molten rock - making their name so much more meaningful!

Scientists believe that over 1,500 million years ago, molten granite rock pushed through the surface of the earth and in meeting with sandstone deposits cooled and formed vertical dome like structures. Over the millions of years following, these structures have been whittled down by natural erosion to be their current shape.