On the subject of Australia today, in the middle of Australia is what is believed to be the largest single rock in the world. It is known as Ayers Rock. It's local Aboriginal name is Uluru.
The great mystery is how it could have formed. At first glance it appears certain to be of volcanic origin.
https://en.wikipedia.org/wiki/Uluru#/media/File:Uluru_(Helicopter_view)-crop.jpg
But it isn't. It is actually made of sandstone, not any kind of volcanic rock. It is not technically a mountain but a single rock. As the name implies, sandstone is a sedimentary rock that forms from grains of sand that have been compressed together. This could not possibly be of volcanic origin.
This massive rock stands alone, with no comparable features anywhere nearby. There is only one possible way I can see how Ayers Rock must have originated, and I cannot find any reference to it online.
We know that a large expanse of flat terrain is almost always the result of seafloor that has been forced upward by tectonic movement. As the pieces that now form the Australian continent moved tectonically closer together, the seafloor between them was forced upward to form the flat areas of Australia that we see today.
Sand is formed along coasts by the action of waves gradually breaking down rocks into grains. It takes a long time for waves to break down rocks into sand, the rocks are first broken down into pebbles, which are smoothed by the action of the waves, before being broken down further into sand.
Grains of sand tend to be oddly-shaped, so that the grains lock together and you can walk or drive on sand. When sand gets older, the edges gradually get worn down so that the grains are more spherical. Without the rough edges, the grains will "roll" when pressure is applied and someone standing on the sand will sink down in it. This type of sand is called "quicksand".
The only way to explain Ayers Rock is that a great meteorite formed an impact crater in a shallow sea, near the shore. It must have been like Meteor Crater, seen here in Arizona.
https://en.wikipedia.org/wiki/Meteor_Crater#/media/File:Barringer-1001.jpg
The movement of the water caused the vast crater to fill with sand. The weight of the water, and the sand at the top, gradually compressed the sand into one gigantic rock. This is how all sandstone is formed.
Then, when the seafloor was later forced upward by tectonic movement, the pressure closed the meteorite impact crater and, being a single rock, the sandstone was forced upward above the level of the flat plain that was formed by the seafloor being forced upward.
This has to be what formed Ayers Rock, although the majority of the rock remains below ground level.
Some distance from Ayers Rock is a similar rock but, unlike Ayers Rock, this rock has multiple peaks. It is known as Mount Olga.
https://en.wikipedia.org/wiki/Kata_Tjuta#/media/File:Aerial_Kata_Tjuta_olgas4799.jpg
But the explanation for this is simple. Before impacting the earth, the large meteor broke into two pieces. One of the pieces then broke into multiple pieces before impacting the earth.
The piece that remained whole is the one that formed Ayers Rock. The other one formed Mount Olga, with each of the fragments that it broke into forming a different piece.
If these great rocks were formed by geological processes, we would expect to see at least a few other examples in the world, but we don't. These two gigantic sandstone rocks require some special explanation, and meteor impacts just off a sandy coast provides it.
No comments:
Post a Comment