It is expected that EACH TEAM wishing to log a find will SUBMIT THEIR OWN ANSWERS to the CO. Once your answers have been submitted, you are free to log your find. If there are problems with your answers you will be contacted. If you fail to submit answers, your log may be deleted.
Maidenwell Granite
There is an excellent example right outside the local watering hole.
How a granite cliff is formed
Granite’s distinctive, granular texture is formed by interlocking crystals that develop as molten rock slowly cools underneath the surface of the Earth, solidifying as individual minerals of quartz and feldspar, along with mica and small amounts of other minerals. The size of the crystals depends on the time it takes for the rock to cool.
The color of granite mostly depends on the type of feldspar it contains. Granite’s plagioclase feldspars are typically milky white. Alkali feldspars have a range of colors — brick red to emerald green to pale yellow — depending on impurities and trace elements. Pink granites owe their color to red or pink alkali feldspars. Gray or white granites may have white-colored alkali feldspar mixed with the white plagioclase, or they may have little or no alkali feldspar at all, in which case they are technically called granodiorites or tonalites.
The term for “granite” actually refers to an igneous rock that is more than 20% but less than 60% quartz, and more than 10% but less than 65% plagioclase feldspar, with the remaining amount consisting of alkaline feldspars.
Granite cliffs can be formed either by tectonic movements or by wind and water erosion.
To log this Earth Cache please answer the following questions:
- Estimate the height of the granite cliff to your west.
- Explain whether you think this cliff was made by tectonic movements or by wind and water erosion.
- Estimate the % of quartz in the light coloured granite (hint: it is often easier to see when it is wet).
- Compare & contrast the granite cliff with the exposed granite to your east. Describe in your own words how you think they are different and why.
