Geology
The rock at Pyramid Hill and the surrounding area is Granite. Granite is an igneous rock derived from magma (lava) that has solidified below the earth’s surface. It is a very coarse grained rock, predominately composed of large crystals of quartz, feldspar and mica. The reason granite is so coarse grained, is because the magma doesn't reach the surface and cools down slowly, thus giving the single crystals time to grow. The longer the granite takes to cool down will develop larger crystals, while a faster speed will give smaller crystals.
The granite on Pyramid Hill contains many interesting open space cavities caused by gases and steam in the parent rock. You can see many examples of this on the walk around the hill. The parent rock the granite formed under was more prone to erosion than the granite which is why Pyramid Hill stands much higher than the existing landscape.
There is another Granite outcrop nearby called Mt Hope.
The Questions
The co-ordinates will take you to an interpretive sign.
Reading the section titled “The Land and People” find the answers to the following questions.
1) The open spaces in the Granite were formed by steam and gases. The gases contained THREE compounds that are named. What are they?
2) Just next to the interpretive sign is a granite rock with a plaque on it. This granite is local to the area. Take a look at the grain structure. Is it coarse or fine, and what colour is it? Also how high is the Granite Outcrop in meters above the plain?
3) Walk along to S36 03.217 E144 08.358. You will find another granite rock with a plaque titled “Site of the first township of Pyramid Hill”. This granite rock is not local to the area. How is it different to the other Granite rocks around? What is the colour and is it coarse or fine grained?
4)Which of the two granite rocks cooled slower and why?
5) Optional - If you would like to you can take a photo of your team near a cavity somewhere on the hill and include it with your log.