The Statue of Neptune stands as an iconic symbol of Bristol's past and present. It serves as a reminder of the city's maritime heritage and close relationship with the sea. Visitors and locals alike can admire the grandeur of the statue, appreciating its historical significance and contribution to Bristol's cultural landscape.
Compulsory tasks in order to log a find against this EarthCache, you will need to visit GZ and make some observations and then answer some questions and send answers to me via my Geocaching profile or through the Messenger Centre.
You won't need a magnifying glass or anything like that to complete the earthcache but if you have one, or ideally a hand lens or even a magnifying app on your smartphone, you'll be able to see the makeup of the rock in much greater detail.
1) Look at the granit plinth, here you can see phenocrysts. Please describe their size, shape, and colour.
2) Using the information below, please tell me whether you think this rock cooled quickly or slowly, give your reasoning for your answer?
3) Are the phenocrysts anhedral or euhedral - please explain why you think this?
4) Also: Include in your log a photograph of you, your GPS or another identifiable item near GZ, taking care not to include anything in the photo that may give away your answers.
Granite
Granite is a common type of igneous rock. Igneous rock is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or lava. Igneous rock may form with or without crystallisation either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks.
It is composed mainly of three minerals: quartz, feldspar, and mica. These crystals form when magma, rich in dissolved minerals, cools slowly underground. As the magma cools, the minerals within it start to crystallise. However when the cooling process is gradual, the crystals have time to grow larger than the surrounding minerals creating phenocrysts, they contrast sharply in size with the enclosing groundmass; this implies a size ratio of at least about 5:1.
Phenocrysts provide valuable information about the conditions under which the rock formed and the history of volcanic activity in the area. Euhedral phenocrysts are characterised by well-defined crystal faces and sharp edges, indicating that they had enough space to grow freely within the magma before it solidified. On the other hand, anhedral phenocrysts lack distinct crystal faces and appear irregular in shape, suggesting that they formed in a confined space or in a rapidly cooling environment where crystal growth was hindered.
