Nepheline Syenite Dyke EarthCache
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15 geological sites are spread around the Pilanesberg National Park. You are now at G2 which is about Nepheline Syenite. Most of the answers to the questions to claim the Earthcache can be found on the information board at the site.
PLEASE DO NOT GET OUT OF YOUR VEHICLE HERE.
A dyke is formed when molten rock intrudes and cuts across earlier formed rocks at shallower depths. The solidified rock constituting a dyke can now be seen at the surface where it is exposed to weathering and erosion.
Pilanesberg National park is located in one of the world's largest alkaline ring dykes. During the volcanic stages in the area, magma pooled up near the surface. Under pressure, the volcanic structure was pushed up several thousand meters tall.
Over time, tubes of magma radiated outwards, causing cracks in the surface around the volcano. After several eruptions, the volcano collapsed in on its self forcing more magma through the cracks.
The magma cooled in the cracks as bands of volcanic rock, mainly syenites and foyaites, here in the Pilanesberg. This is how the dykes were formed in this area.
To claim this Earthcache you will need to send the answers to the following questions to us via our profile page.
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What does Nepheline Syenite mainly consist of?
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Describe the shapes and colours present in the polished sample below the information board?
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What caused the crystals to be orientated the way they are?
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Take a photo, while in your vehicle, of your caching name on a piece of paper with the information board in the background.
We hope that you might have garnered a bit of knowledge here. We did.
Additional Hints
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