In 2014, the Staple branch of the Royal British Legion decided to do something to remember the young men of the village who had given their lives in the wars, referred to as “The Lost Sons of Staple”. A Garden of Remembrance was built with a memorial stone and nine smaller stones - for each “Lost Son” - along with nine silver birch trees. Each year a wreath is laid in the garden on Remembrance Day and the garden has become a focal point for the close-knit community. This Earthcache is about the memorial stone.
Geology is a branch of natural science concerned with the Earth and other astronomical objects, the rocks of which it is composed, and the processes by which they change over time. There are three groups of rocks on Earth : igneous rocks, sedimentary rocks and metamorphic rocks. Igneous rocks are formed when magma cools in the Earth's crust, or lava cools on the ground surface or the seabed. Sedimentary rocks are formed are formed by the weathering, transport, and deposition of existing rocks. Metamorphic rocks are formed when existing rocks are subjected to such high pressures and temperatures that they are transformed without significant melting.
Amongst igneous rocks, solidification of magma can occur either below the surface as intrusive rocks or on the surface as extrusive rocks. The big difference between intrusive and extrusive rocks is the rate of cooling, which effects the size of crystalisation. Extrusive igneous rock that cools rapidly on reaching the surface, forms very small or no crystals to create natural glasses, whereas intrusive rocks cool very slowly, allowing crystallisation to form granular, crystalline rocks. Intrusive igneous rocks make up the majority of igneous rocks and are formed from magma that cools and solidifies within the crust of a planet. The mineral grains in such rocks can generally be identified with the naked eye. Common intrusive rocks are granite, gabbro, or diorite.
Granite is a coarse-grained intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies underground. It is common in the continental crust of Earth, where it is found in igneous intrusions.
Now take a look at the memorial stone or any of the nine smaller stones. They are all examples of Norwegian granite, sometimes called Larvikite or Blue Pearl granite. To log this earthcache, please answer the following questions and send via the message centre to the CO. There is no need to wait for a reply before logging and whilst a selfie at the location is not mandatory, it would be good to show that you visited the site if you can.
1. Please describe the memorial stone in terms of colour, texture (rough or smooth), crystalisation (coarse or fine) and shape of any crystals you can see.
2. From your answers and the description above, deduce whether you are looking at an intrusive igneous rock or an extrusive one. Estimate how large the biggest crystals are. Does this suggest rapid or slower cooling?
3. Look at the inscribed and polished plaque on the main memorial stone, please state what group of rocks this might be (igneous, sedimentary, metamorphic) and hazard a guess at what type (you may have a kitchen top like it).