To complete this EC, you will be asked to examine the wall of Glasgow Central Train Station at approximately 1 Hope Street / 240 Argyle St (roughly) to look for examples of cross-bedding and exfoliation in the sandstone walls.
You will need to complete 3 logging tasks: to take a specific photo at GZ and to answer 2 questions. In order to log your find, you must complete the logging tasks and send me the answers, first. I will read and respond, and if anything is amiss, I will let you know. Logs that do not meet the requirements will be deleted. If you are going to be delayed in sending a response, post a write note in the meantime.
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1. Required photo for all cachers - Take a photo of you / an object that clearly shows you at GZ with the words "Central Station" FROM THE BRIDGE - NOT THE WALLS - clearly evident. I'm told this is called ‘The Heilan’ Man’s Umbrella’!" locally. POST this unique photo with your log.
2. Look at the sandstone walls at GZ. Identify the direction of the cross-bedding. Explain what that tells you about the palaeoenvironment at the time the rock was formed.
3. Find examples of exfoliation on the sandstone walls. Tell me where they are located (i.e. what part of the wall), the size (thickness) of exfoliation and why you think it exfoliated in the location.
Responses to submit - if submitting responses for a partner, be sure to include their geocaching name with your response. EACH PERSON, however, must submit their own photo demonstrating they were on site (see Q1 below).
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Glasgow Central Station (geological highlights)
Glasgow Central Station is primarily constructed with a combination of cream-coloured sandstone, particularly for the upper storeys and entrance columns, and granite for structural elements and foundational works. The building often features red Locharbriggs sandstone for detailed carvings and flesh-coloured Peterhead granite on its lower levels. (source: British Geological Survey).
Key details about the stone and materials:
- Sandstone: The upper portions are clad in cream sandstone from Stainton, England.
- Granite: Flesh-coloured Peterhead granite is used on the lower storeys, pillars, and balustrades.
- Structural Stone: The old approach viaducts used Dalbeattie granite for the piers.
- Interior Materials: The entrance features white marble floors and dark brown Italian travertine on the walls.
- Roof: The station is famous for its massive glass roof, which consists of 48,000 panes.
In addition to the sandstone noted above, Glasgow buildings prominantly display local quarried blonde sandstone and latterly red sandstone sourced from Dumfriesshire.
Petrography:
Stainton sandstone is from the Coal Measures of Carboniferous Age. It is a finegrained stone, buff in colour with a fine brown speckle. Stone is extracted from a 10.5m face below about 3.6m of overburden. Large blocks are available but it is generally supplied at depths of 1.2 – 1.5m on bed.
Sandstones from the Carboniferous series are traditionally acknowledged as generally being a very durable building and paving stone and have been used extensively in many towns and cities in the UK. Stainton sandstone appears to be a durable stone that is not effected by acid rain or air pollution. The high weight lost in the harsh saturated sodium sulphate crystallisation test indicates limited resistance to salt damage in very severe environments (for example in coastal locations or from de-icing salts); sandstones usually have good frost resistance. The compressive strength of the stone is typical of the range for sandstone. The flexural strength is towards the lower end of the range for sandstones and if used for paving then the units may need to be thicker than those for some other sandstones. The abrasion resistance result suggests that the stone may wear excessively if used in heavily trafficked areas. Overall, should be suitable for use in most aspects of construction including flooring in lightly trafficked areas, load bearing masonry and cladding.
Source: Stainton Sandstone
Formation Process
- Deposition: The stone originated from sediments deposited in ancient river channels, deltas, or coastal plains.
- Lithification: Over millions of years, these layers of sand were buried under subsequent sediment layers. The immense pressure (compaction) and mineral cementation (primarily silica) bound the sand grains together into solid rock.
- Composition: It is primarily composed of quartz grains with mica, and contains kaolinite clay within its pore structure.
Source: British Geological Survey
Unique Features - Cross-bedding and Exfoliation
Look at the walls at GZ (especially near the base). Look for examples of both cross-bedding (internally composed of inclined layers) and exfoliation (surface-parallel fracture systems in rock which often lead to erosion). Cross beds form from running water. As the water flows, it creates bedforms, such as ripples or dunes, on the floor of the channel. Sediment deposited on the downcurrent side of these bedforms is deposited at an angle--not horizontally. If preserved, the layering is also inclined and dips in the direction of water transport.
Cross-bedding (image)
Exfoliation (image)
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This is a SideTracked cache. Here's some information about the station.
Glasgow Central (Scottish Gaelic: Glaschu Mheadhain), usually referred to in Scotland as just Central or Central Station, is one of two principal main line rail terminals in Glasgow, Scotland. With 25 million passengers in 2023–2024, it is the fifteenth-busiest railway station in Britain and the busiest in Scotland, as well as the third busiest station in the UK outside of London, behind Birmingham New Street and Manchester Piccadilly.The station is protected as a category A listed building. The station was opened by the Caledonian Railway on 1 August 1879 and is one of 20 managed by Network Rail. It is the northern terminus of the West Coast Main Line (397 miles or 639 kilometres north of London Euston). As well as being Glasgow's principal inter-city terminus for services to England, Central also serves the southern suburbs of the Greater Glasgow conurbation, and the Ayrshire and Clyde coasts. (Wikipedia)