The Sisters Rocks, 3km SE of Stawell, are huge granite tors named after the three Levi sisters. The mining family set up camp here in the gold rush days. They are now smothered in graffiti which ruins or enhances the boulders, depending on your opinion.
These massive boulders are made of granite that was extruded into the surrounding rock about 500 million years ago. An application made in 1867 to protect the rocks from being destroyed as a source of building material. The Sister's Rocks have been protected since 1873. This area is probably one of the first protected sites in Australia.
Tors are the result of millions of years of weathering. The rocks at the earthcache were formed 500 million years ago deep within the earth. Granite rocks are plutonic igneous rocks, which were formed by slowly cooling pockets of magma trapped beneath the earth's surface. Granites are typically a hard rock with visible crystalline texture, rich in quartz and feldspar. An outcrop of granite on the earth's surface requires some kind of erosion to expose the buried material.
Now to your earthscience tasks.
1. Estimate how many litres of paint have been applied to the large boulder in front of you? One method would be to measure the area, measure the dry film thickness, calculate the dry volume, estimate the paint solid to liquid ratio, and calculate the volume of liquid. Describe your specific method to determine this volume.
2. How long will it take for the lichen to grow back over the GRUB KAYE carving? Lichen is symbiotic plant with a growth rate between 0.1 and 50mm per year. Growth rates for different areas and species can be obtained by measuring maximum lichen sizes on substrates of known age, such as gravestones. Describe your reasoning for the time period in your estimate.
3. Estimate the Moh's hardness of the rock. The rock hardness is the property that has allowed it to remain while the surrounding matrix has eroded. Describe your method for estimating the rock hardness.
4. Optional photo, and your opinion on the graffiti?