Building the Canals
If you're reading this then you are probably walking along the Shropshire Union Canal - an impressive feat of engineering. But do you know how it was built? When you dig a canal the channel has to be lined to make it waterproof, otherwise all the water would soak away and this would make all the boaters very sad. The materials used for building depended on what was available in the area. Limestone or sandstone could be used to build the sides, but in many places clay kept the water in the canal. Typically stone or brick and wood were used to build locks. On this stretch of the canal we have two locks which you will look at for the purposes of this EarthCache, Beeston Iron Lock and Beeston Stone Lock.
Image: David Martin / Beeston Stone Lock, Shropshire Union Canal / CC BY-SA 2.0
Beeston Locks
As the name would suggest, the rather unusual Beeston Iron Lock is built of iron instead of the conventional stone or brick - it is the only one like this on the entire canal network! It replaced the original lock which had collapsed at the site in 1797. This is due to the prevailing geological conditions regarding the substrate.
The definition of a geologic substrate is a surface (or volume) of sediment or rock where physical, chemical, and biological processes occur, such as the movement and deposition of sediment, the formation of bedforms, and the attachment, burrowing, feeding, reproduction, and sheltering of organisms.
Alan Murray-Rust / Beeston Iron Lock / CC BY-SA 2.0
Start at the posted co-ordinates, this is Beeston Stone Lock, which is built like a traditional lock on the canals.
1. Look at the stone used to construct the lock, what can you tell me about it's appearence? Please describe the colour and general appearance of the stone.
2. What stone do you think was used in the construction of the stone lock? Please refer back to your answers from Question 1 to explain your answer.
3. Why is this stone typically used as a material for building locks? Think about the qualities that it might have.
4. Are there any obvious signs of weathering or erosion to the stone? Please describe what you see.
Now go to the additional waypoint, this is Thomas Telford's unique Beeston Iron Lock.
5. Compare what you see at the Iron Lock to the Stone Lock. Are there signs of weathering or erosion? How do these differ from the stone lock?
6. Look at the structure of iron lock, making reference to what you've learned about the local geology and what you can see, why do you think it was built like this?
Optional - Upload a photograph of yourself or your GPS with either of the locks in the background.
Remember, its about having fun, having a go and hopefully learning something. Your answers will not be used in Geologists Weekly. However please do make sure you send the answers within good time of logging the cache!