|
The tops of many hills and ridges in Girraween National Park are graced by large boulders. These are the last remnants of enormous sheets of granite that have fractured and weathered away over millions of years.
Extreme examples are the balancing rocks. Here, the granite sheets have cracked into fragments and weathered into piles of boulders – rather like stacked rows of children's building blocks. On some boulders, this weathering has occurred not only on the upper surfaces and sides, but also on the underside. The boulder ends up being shaped so that it is resting upon only a small base – the "balancing" point. Eventually, some balancing rocks become unstable and roll off their perches. When a balancing rock from an upper layer topples over, it may fall onto boulders from the layer beneath it to make an arch. It is thought that this is how Granite Arch may have formed.
For more on how Girraween's amazing granite features were formed, see our Geology pages.
|
Click on the thumbnails to go to the larger image.
|
|
|
|
|
|