Schist is a crystalline metamorphic rock, mainly composed of more than 50% tabular and elongated minerals with a grain size coarse enough to be visible to the naked eye. Schist has a developed tendency to split into layers. These layers are plain to see at the published coordinates. There are two large exposures of schist to be seen on either side of the path.
The word ‘schist’ comes from the ancient Greek word for ‘split’. Schist is formed at high temperatures and pressures, which aligns the grains of mica and other elongated minerals into thin layers. At least half the grains in schist are aligned in this layered way.
Schist is named after its predominant mineral, and the schist at Wicklow Head is mainly composed of mica.
Mica is a shiny silicate mineral and can be found as either minute scales in various rocks or as crystals. The type of mica occurring in the schist at Wicklow Head is called flake mica. Look closely at the schist here: can you spot any flake mica?
The mica schist at Wicklow Head was formed during the Ordovician Period, making it younger than the Cambrian Rocks at Bray Head and Sugar Loaf Mountain to the north. This period covers the time between 485 and 443 million years ago.
To log this earthcache as a find:
1.At the coordinates, there are two exposures of schist on either side of the path. Estimate the height of the smaller of the two, at its tallest point.
2.Look closely at the layers of schist: describe the colours and shapes you see. Are the layers mainly horizontal or vertical? Can you see any flake mica?
3.What type of rock is schist? Igneous, metamorphic or sedimentary?
Do not wait to log your find online; please send me your answers via my profile page and I will contact you if there is any problem. Online logs without any email will be deleted if the email is not received within a reasonable period of time.
Getting to GZ
The narrow road to GZ is frequently used by locals for walking dogs. The oldest of the three lighthouses here is rented out as a holiday home. There are also some houses dotted along the road. When you park your car, please be careful not to block the gate leading to the lighthouses, as this must be kept clear for the emergency services. You can also choose to park your car near the main road and walk up the path to GZ.
Happy Earthcaching!