The co-ordinates for this Earthcache take you to a statue that goes unnoticed by many on their walk to work, or arriving in Inverness via the train station. It's a memorial to the 79th Queen's Own Cameron Highlanders and pays tribute to some 141 officers and soldiers. These men lost their lives from all causes during campaigns in Egypt (hence the mini Sphinx!) and the Sudan, between 1822 and 1887.
Sculpted by George General Wade, the statue was the first war memorial in Inverness and unveiled in Station Square in 1893. It is made of Portland stone and sits on three granite steps.
Portland stone is an example of limestone and comes from the Jurassic period, specifically the Tithonian stage. It's sourced from the Isle of Portland in Dorset and has also been used in London during the construction of St. Paul's Cathedral and the Cenotaph.
Portland stone is formed on the bed of a shallow, warm sub-tropical sea. As the sun heats the water, it releases dissolved carbon dioxide, which allows calcium and bicarbonate to mix and form calcium carbonate. Billions of these tiny mixtures build up into a lime mud called micrite. Sand and organic material interact with this mud over time, coating it in calcite. This too builds up (like a rolling snowball) into small ball-like shapes which are fused together by more calcite to create Portland stone. Once the sea retreated, oxygen rich rainwater percolated the porous stone, burning away impurities and leaving a creamy-white finish. Its strength level is such that the Portland stone can be cut and carved easily, but also withstand weathering.
Weathering is essentially the breaking down of rocks on the surface of the Earth. There are 3 main types that are responsible for this damage. They are physical, chemical and biological. Physical weathering is primarily down to ever-changing temperatures. Freeze-thaw, for example, happens when water seeps into cracks, expands in the cold, and breaks the rock apart over time. Chemical weathering occurs when rainwater reacts to the mineral grain composition of a certain type of rock, slowly dissolving it in a solution. The best example is the action caused by acidic rainwater (containing dissolved CO2) coming into contact with limestone. Finally, biological weathering takes place due to the growth of organisms that interact with the rock. Think lichen covering a rock's surface or a tree growing in a crack along a boulder.
Granite is an igneous rock formation that formed as molten magma cooled and solidified deep underground during the Carboniferous period, 300 million years ago. The slower the magma took to cool, the bigger the crystals appear in the finished product. If it cooled quickly, the crystals appear smaller. Chemical phase is another factor that can alter crystal appearance.
Crystal size is a clue into the history of a rock. The presence of larger crystals tells us that it spent longer underground in its formation, away from the cooler air of the surface. These are known as intrusive rocks. The surface might remind you of a speckled bird's egg. Some of the "dots" may be hard to pick out, or massive in comparison!
Granite can be thought of as a solid lump, which reduces overall weaknesses, and makes it a popular choice for building material.
To log this earthcache, please email me (or message using Geocaching.com) answers to the following. Logs without the accompanying email/message may be deleted in time, but feel free to log the cache before my reply!
1) Considering the statue was 123 years old at the time of this cache being placed, is the statue in good condition with regards to the detail of the soldier and the text? Using your observations, would you put this down to statue placement or the choice of Portland stone as a building material?
2) Why do you think Portland stone has been so popular in building use?
3) The Jurassic period that formed Portland stone was roughly between 201 and 145 million years ago. Identify the specific stage it was produced in and use that information to narrow down the stone's possible age range.
4) Take a close look at the three granite steps at ground floor level. Describe the colour of the base and the colour of any crystals you can see. Are there a few crystals or many?
5) Do you think the granite cooled quickly or slowly?
6) The statue and plinth are Portland stone, but the steps are granite. Why the difference in material?
7) OPTIONAL: Post a photo of your GPS at the statue.