Standing at an impressive 108 feet tall, the Bridgewater Monument stands on a ridge overlooking the Ashridge Estate. The monument is constructed from Aberdeen granite and sits on a plinth of York stone, with copper on a wrought iron base being used for the vase that sits on top. The monument was designed by Sir Jeffry Wyattville, who was also responsible for the more recent additions to nearby Ashridge House.
The monument was erected in 1832 in memory of the 3rd Duke of Bridgewater Francis Egerton, who is described on the monument as 'The Father of Inland Navigation'. The 3rd Duke gained his reputation after he ordered the construction of a canal from his coal mines at Worsley to Manchester, and then on to Runcorn and the River Mersey. Prior to this the only method of transporting this coal was by road, which made it expensive. Bridgewater's canal was the first of some 2,300 miles of inland waterway to be constructed in the UK over the following century.
Granite is a common form of igneous rock (meaning that it formed in the cooling of magma) for which the crystals are visible to the naked eye. Predominantly white, pink or grey in colour the name granite comes from the Latin granum meaning grain. Granite is typically made up of 20% quartz and 65% feldspar, in addition to other minerals, which differ depending on where the granite comes from.
While the crystals in granite are always visible to the naked eye the actual crystal size can differ depending on how quickly the newly formed granite cooled from metamorphic rock. Granite that cooled faster will have smaller crystals as they did not have time to form. Granite that cooled slower will have larger crystals.
Aberdeen granite comes from the city of Aberdeen in Scotland. Much of the city is built in locally quarried granite, earning it the nickname The Granite City. Due to its high mica content Aberdeen granite has a certain sparkle to it in the right light, which can clearly be seen in the artificial light of the stairwell leading to the top of the monument. Quarried for the last 300 years at the Rubislaw Quarry near Aberdeen, Aberdeen granite has been used as a building material in the Houses of Parliament and Waterloo Bridge.
York stone is a variety of sandstone, which is a type of tight grained, Carboniferous sedimentary rock (it was formed by the conglomeration of grains or sediment in fluid over millions of years). Specifically from quarries in York, there is no actual definition of York stone. The stone consists of quartz, mica, feldspar, clay and iron oxides. Known for being hard wearing, reasonably weather resistant, and durable, York stone has been used in a wide array of buildings and other applications around the world for many years. In Yorkshire, split stones called thackstone (Scots thack, English thatch) have been used as roofing, and the traditional London paving stone has been York stone.
ONTO THIS CACHE!
In order to be able to log this earthcache please answer the questions below and email them to me using either the email link or the message center via my profile at the top of the page. Please feel free to log the earthcache as found before you have received a response from me, however any logs without an accompanying email may be deleted without further notice.
- Can you see where the York stone ends and the Aberdeen granite begins? How can you tell the difference between the two types of stone? What can you see in the external stones at the base of the monument that might give you a clue as to their nature?
- Find a section of York stone. Describe what you see in terms of colour, texture and grains.
- The stones at the base of the monument are quite heavily stained. What could be the cause of this staining?
- York stone is often used as a building material and in London is commonly used for paving slabs. What qualities of York stone make it an excellent building or paving material?
- Find a section of the Aberdeen granite and describe what you see in terms of colours, texture and crystals. How big or small are the crystals? What does this say about how quickly the granite cooled?
Climbing the monument to the top is not a requirement to log this earthcache, but it does give you the opportunity to see the granite close up without any staining, and the mica shows up beautifully in the artificial light of the stairwell. There's also a great view from the top! The monument is only open at certain times on certain days, and is never open during inclement weather. There is an entry fee for going into the tower, unless you are a member of the National Trust.
Photos of your visit are always welcome though are not a requirement to log this cache. The phone signal at the top of the monument is pretty good too.
Permission for this earthcache has been given by the National Trust.