Just a bunch of Rocks?! The Canongate Wall EC EarthCache
Just a bunch of Rocks?! The Canongate Wall EC
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The Scottish Parliament building is a unique building, often evoking a strong emotional response to its exterior. I was surprised to recently discovery (thanks to the Edinburgh Geology Society) that it also commemorates Scottish geology and showcases an extensive display of Scottish rocks. To claim this earthcache you visit the Canongate Wall of wisdom.
The coordinates take you to the beneath the Canongate Building façade to the ‘Canongate Wall’. Here, and in and around the parliamentary complex, a range of quotations have been inscribed onto the stonework. This wall of wisdom is of extra interest because it is constructed from a variety of indigenous Scottish rocks, showcasing the geologic history of Scotland. Rock types present include Iona marble, Lewisian gneiss, Torridonian sandstone, Caithness flagstone and Easdale slate. The stones are set into large concrete casts, each one inscribed with a quotation. There are a total of 24 quotations on the Canongate Wall. Also at this location is a beautiful etched pictorial representation of the ‘Old Town’ based around a sketch by the Parliament’s Architect Enric Miralles showing the view of the Old Town from his bedroom window in the Balmoral Hotel. Miralles is quoted to have said -
“We don't want to forget that the Scottish Parliament will be in Edinburgh, but will belong to Scotland, to the Scottish land. The Parliament should be able to reflect the land it represents. The building should arise from the sloping base of Arthur’s Seat and arrive into the city almost surging out of the rock.”
The overall design of the Canongate Wall was by Sora Smithson with the Scottish rocks embedded carved by Gillian Forbes and Martin Reilly. The wall also includes “Brewery Stones” recovered from the building demolished to make way for the new Parliament building.
Geologists categorise rocks into three types sedimentary, igneous and metamorphic. Examples of all three types from locations around Scotland are depicted here.
Sedimentary rocks form when small pieces of rock and animal remains that are weathered, are swept downstream and eventually settle on the seabed. As the sediment deposition builds up in horizontal layers the pressure from above cements the minerals together and turns them into rock.
Igneous Rocks (sometimes called fire rocks) are crystalline rocks formed from solidified magma and are formed either in volcanoes where lava and ash form extrusive rocks such as basalt and tuff, or as intrusive rocks when magma gets trapped in underground pockets cooling slowly examples of this type of igneous rock includes granite.
The final rock type Metamorphic form from other rocks that are changed because of heat or pressure. Earth movements or proximity to lave can cause rocks to be heated, deeply buried or squeezed. When some rocks are heated and put under great pressure, rather than melt the minerals they contain are changed chemically, forming metamorphic rocks.
The Canongate Wall displays a remarkable variety of different kinds of sedimentary, igneous and metamorphic rocks, reflecting Scotland’s long and complicated geological history. Over the past three billion years, these rocks have moved over the Earth’s surface, experiencing a range of environments and climates. Fragments of the geological units that now make up Scotland have collided, slid past each other and been torn apart by the actions of plate tectonics. The rocks are not wholly representative, as harder stones are more resistant to weathering and erosion and tend to survive longer.
To claim this Earthcache find the large strip of three grey rocks in the wall and send me a message with answers to the following questions. If you need help look for writing on the roadside!
1.What is the name of these rocks?
2.Which type are they i.e. Igneous, Sedimentary or Metamorphic?
3.What were they formed by?
4. Approximately how long ago were they formed.
5. Which is your favourite rock type, and why.
6. As you look at the quotes on the wall which do you like best?
7. To the left of the 3 large grey rocks, is another panel with more rocks. Take a good look at the topmost and the final rock on this column. Describe the similarities and differences. Are these the same type of rock? Explain your answer.
Please don't put the answers in your log. Logs without an accompanying email will be deleted.
I would highly recommend the more detailed leaflet on the Cannongate Wall which can be downloaded from the Edinburgh Geological Society at (visit link)
Additional Hints
(Decrypt)
Nyy gur vasb lbh arrq pna or sbhaq ng gur jnyy naq fheebhaqvat vafpevcgvbaf, whfg ybbx pybfryl.