Whitstable Castle in Kent, UK is made from ragstone and Caen stone. The castle's octagonal tower was built from bricks that came from the copperas works that once stood on the site. Charles Pearson, a London businessman, built the castle's tower in 1790 using bricks from the copperas works. The castle's walls are made from ragstone, and Caen stone was used for some of the castle's features. The castle has been owned by many different people over the years. In 1935, the Whitstable Urban District Council bought the castle for the town.
Sedimentary rocks are rocks formed from sediment. They are deposited over time, and often show layers which can be seen in cliffs. Sediments are usually formed from matter which falls to the bottom of oceans and lakes. The matter includes tiny pieces of other rocks, and dead animals, plants and microorganisms. The three most common sedimentary rocks are limestone, sandstone and shale.
Limestone is a sedimentary rock. Historical information as well as buildings still standing point to limestone as a very durable and time-tested building material. It is composed mostly of calcium carbonate (CaCO3) in the form of the mineral calcite. It most commonly forms in clear, warm, shallow marine waters. It is usually an organic sedimentary rock that forms from the build-up of shells, coral, algae and debris. It can also be a chemical sedimentary rock formed by the precipitation (release) of calcium carbonate from lake or ocean water. Caen stone is a fine-grained, creamy-coloured limestone that is quarried in Normandy, France. Caen stone is a Jurassic limestone that was formed in shallow water lagoons about 167 million years ago. It is used in many buildings in England, including cathedrals and churches. Caen stone is a good freestone, meaning it has a uniform texture and few distinguishing features. This makes it easy to lay in any orientation.
Sandstone is a sedimentary rock made up of tiny grains of mineral, rock, or another organic material. It also contains a 'glue'-type material that binds the sand grains together and may contain silt or clay particles that fill the gaps between the sand grains. Sandstone also is often mined for use as a construction material or as a raw material used in manufacturing. Inside the Earth, it often serves as an aquifer (underground layer of rock which holds substances) for groundwater or as a reservoir for oil and natural gas.
Shale is a fine-grained sedimentary rock that forms from the silt and mud compacting. This composition places shale in a category of sedimentary rocks known as "mudstones." Shale is different from other mudstones because it is laminated (made of many layers) and fissile (often splits into thin pieces along the laminations).
Weathering is the wearing down or breaking of rocks while they are in place.There are three types of weathering: biological, chemical, and mechanical. Rain is actually mildly acidic, and therefore slowly eats away at rocks - this is an example of chemical weathering. In the UK Low-pressure systems containing lots of rainfall form over the Atlantic Ocean and approach the UK from the west. Plants and animals also cause rocks to erode - this is an example of biological weathering. Lichens and other growths can also damage sandstone, as they produce chemicals that break down the stone. It can also cause more cracks and holes to appear. Water can seep into the cracks of rocks, as the temperature cools and this water freezes and forms Ice crystallization, also known as ‘ice wedging’ or ‘frost wedging’, is a process that occurs when water is allowed to seep into a pore or crack in the sandstone where it freezes (as water expands when frozen, this could actually fracture the stone). this causes rocks to break away - this is mechanical weathering.
To log this cache, please complete the tasks below using the information above and your observations at the Castle. Please send your answers via message at the same time as you log the cache, there is no need to wait for a reply
- Using the information in description and your own knowledge of what you can see here, suggest what type of rock Kentish ragstone is and what features tell you this
- Which side of the Castle has the most renovation due to weathering North, South, East or West?
- Why would one side of the Castle be more weathered than the rest?
- Observe the structure what qualities do you think the Caen stone has for the use on the building compared to the Kentish ragstone
- As an optional extra, post a picture of yourself or your GPS at the Castle
Any logs not complying with the above will be deleted,