There are many different War Memorials across the County Borough which you can visit for commemoration and remembrance of servicemen and women who gave their lives in fighting for their country during the two World Wars and other conflicts. This Memorial is on the main road with some on street parking near-by.
The aim of this EarthCache is to examine, in detail, a rock which is not native to the South Wales Coalfield.
Granite is one of the oldest rocks on Earth, with some forming as early as the Precambrian age, which began about 4.5 billion years ago.
Granite is a type of igneous rock. This broad category of rocks forms when hot, molten rock cools down very slowly — as the rock cools, it crystallizes and solidifies.
To identify an igneous rock that could be granite, look for rocks with crystals. Look for shiny, flat surfaces within the rock — these are the crystal faces.
Red granite is an igneous rock that forms when magma cools and solidifies deep within the earth's crust over millions of years:
The rock we’re looking at has some interlocking grains, or in other words, the rock’s grains are touching each other along their crystal faces. These grains are large enough to be seen by the naked eye with no magnification needed. Geologists call this texture phaneritic. Rocks with crystals too small to be seen without the aid of magnification are called aphanitic.
All rocks are made of minerals. The primary minerals in granite are feldspar and quartz, and mica. You’ll learn to identify each of these minerals here. Sometimes, there are other darker minerals that are likely amphibole/hornblende depending on the specific type of granite.
This red granite is a type of igneous rock that's a variation of pink potassium feldspar granite, with a redder colour. It's a dense, felsic rock with a phaneritic texture. Red granite gets its colour from iron oxide in haematite grains or inclusions within feldspar
Alkali feldspar
The column is ‘red granite', which is a felsicigneous rock and a type of granite rich in the mineral potassium feldspar (K-spar). It is a dense rock with a phaneritic texture. The abundance of K-spar gives the rock a predominant pink to reddish hue; peppered with minor amounts of black minerals.
Feldspar
These minerals are the distinct pink/red crystals you see in red granite—specifically, they are alkali feldspars. Alkali feldspar crystals come in varying shades of pink and red, from light pink to salmon to brick red. Other types of feldspars in granite are white or clear, resulting in a wide range of granite colors.
Feldspar crystals will have sharp angles and shiny crystal faces. Geologists call these distinctive angles and flat, shiny faces cleavage. Cleavage is related to the crystal structure of a mineral. Minerals with cleavage will break along cleavage planes. Feldspar crystals have two planes of cleavage that meet at 90° angles.
Quartz
Quartz has no cleavage; instead, it exhibits conchoidal fracture. Conchoidal fracture means that there are no distinct angles or planes of fracture in the mineral. Unlike feldspar, quartz fractures in more smooth, concave, or curved patterns. Luckily, there are other characteristics we can use to identify quartz. If you have found a quartz crystal in your sample, you’ll see that it is likely milky white in color and a little dull on the surface, or as geologists would say, it has a vitreous luster. Luster (the way a mineral reflects light) is another diagnostic feature geologists use to identify minerals. The two major categories of luster are metallic and non-metallic. There are many subcategories within each broad category.
Mica
While the vast majority of minerals in red granite are either quartz or feldspar, a small portion of red granite is made of mica. These crystals will appear to be a shiny gray-brown or clear in color. Mica forms as flaky sheets and is very easily scratched compared to other minerals like quartz and diamond. The hardness of minerals is yet another identifying factor geologists use to determine what mineral they are examining.
Please log your find, at the same time as you send your responses to:-
LOGGING TASKS
- Can you see interlocking crystals? Do they all interlock or are some on their own? Use the guide to identify crystals by name.
- Pick an area about the size of postage stamp. ( about 1” or 25mm square ) Identify all of red granite’s major minerals (feldspars, quartz, and mica). Describe the size of the crystals and the approximate percentage of each.
- What is the significant difference between the column and the plinth?
- Which of these terms is true of the rock in the column - phaneritic / aphanitic / felsic
- There’s a post box directly across the road. Take a photo of yourself or a personal item from there to include the memorial. - (This is to avoid any close-up 'spoiler' photos.)
☆ You need to fully complete the logging. You need to submit your answers yourself. Group responses will not be accepted.
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From the series owners:
There is a web page for the series [https://warmemorialseries.co.uk](https://warmemorialseries.co.uk/) and a facebook page, just search War Memorial Geocaching. There are badges for your profile (Finders and Setters) and loads of info.
“If anybody would like to expand to this series please do, I would just ask that you could let Just-Us-Two know first at justustwo1013@gmail.com so they can keep track of the memorial numbers and names to avoid any duplication.
FTF Honours go to 🌟 welshman 65 🌟