At the posted coordinates you will have completed the Castle Rock Walk and be at the beginning of the Granite Sky Walk. The Granite Sky Walk is over more challenging terrain with climbing over boulders and a seven meter vertically ladder. You will not have to complete the Granite Sky Walk to complete this cache but it offers some amazing views of the Great Southern. The posted coordinates take you to the foot of the Castle Rock. This cache involves a 4.6km return walk and the walk covers difficult terrain with a significant elevation gain. The Porongurups run for 12km east to west and they rise up to 670m above sea level. They were formed around 1.2 billion years ago. The Porongurups are mostly made of granite and granite is an igneous rock. Igneous rocks are formed from cooling molten material. There are two types of igneous rocks volcanic and plutonic. Volcanic igneous rocks a formed when molten material cools above ground. Because the molten material is above ground it is called lava. Due to the fact, volcanic rocks cool above the ground they cool quickly which means that the crystals in these rocks are large. Plutonic rocks on the other hand are formed below ground also in molten material but this molten material is called magma because it is below the ground. Due to the fact the plutonic rocks are cooled below the ground they cool slowly and that means that small crystals are formed.
Weathering of granite rock is slower than the surrounding rocks in this area. Weathering results in fractures to forming in rocks. One such example of the weathering of granite is the formation of the balancing rock which can be seen by completing the 4.6km return walk to the Granite Sky Walk.
A fee is required to park at the parking waypoint.
At the posted coordinates 1. Examine the rock formations here, what is the average crystal size of the granite? 2. Based on your examination of the granite here is granite a plutonic or volcanic igneous rock? 3. Observe the granite forms around you, what shape are they? Suggest a reason why they may be this shape. Optional- post a photo of your journey.