THE WORLD'S BIGGEST PORKIE?
It's hard to know why Uluru is still regarded as the 'world's largest monolith' when there is ample literature pointing to Mount Augustus in Western Australia as being the largest. It is roughly 2.5 times larger in mass and height, rising 858 meters above the surrounding land. With all due respect to Mount Augustus, the tag of world's biggest monolith isn't likely to inspire hordes of people to visit it in quite the same way Uluru does.
There's another small problem with the description in that there is a bit of weight behind the theory that Uluru is not actually a monolith at all, i.e. a single rock, but is actually part of a huge, predominantly underground rock formation that also includes Kata Tjuta (the Olgas) 35km to the west and Atila (Mount Connor), a mesa tableland, approximately 100km to the east of Uluru.
JUST A QUICK RECAP ON THE LAST 600 MILLION YEARS
Going back about 600 million years, large parts of Central Australia were below sea level in what is called the Amadeus Basin. Rivers from nearby mountains dumped large quantities of sedimentary rocks into the Amadeus Basin which then started to rise out of the sea about 500 million years ago. With little or no vegetation to protect the mountains from erosion, great rivers would have formed carrying tonnes of sediment which would quickly build to form alluvial fans. Layer upon layer would have built up to eventually form Uluru from a section of one of the alluvial fans.
The sea eventually invaded the area again depositing more sand and mud burying the alluvial fans. Over this whole protracted period the profound pressures and squeezing together transformed the deposited sand, gravel and mud into solid rock.
IT'S TOUGH BEING A ROCK
Between 400-300 million years ago the area was subject to another bout of mountain building with landmasses colliding causing more uplift, folding and faulting, breaking up the alluvial fan and the various layers above and below. The future Uluru was a part of one of these alluvial fan sections which has been tilted on its side at almost 90° so all the sedimentary layers are on their side.
After millions and millions of years of continued weathering, Uluru, Kata Tjuta and Atila survived the erosion as they were made of harder rock than that which surrounded them. More recently, about 70 - 60 million years ago, the climate was much wetter which then washed sand and other elements back into the low lying land which smoothed out the landscape leaving only Uluru, Kata Tjuta and Atila protruding out of the desert.
SO WHAT THE HELL IS IT??
So is Uluru actually a monolith or is it one giant rock formation that stretches 130km's from Atila (Mount Connor) to Kata Tjuta? Or perhaps it's a massive pebble sitting in that giant rock formation rather like a big chunk in conglomerate rock, but on a colossal scale?
Best we turn to a Trekkie for clarification ...
"It's a Rock Jim, but not as we know it".
