Geology and Masons: Ramblings on UK Castles and their trappings

Two weeks ago I wrote a brief blog post for my lapidary club’s page about castles; how were they built, and what are they made of? When I initially picked this topic to work in conjunction with my club’s Facebook page, I had not taken into account my utter lack of knowledge about castles. I was essentially trying to think of theme that somehow worked with my background in archaeology but also related to the field at hand, geology. The two fields on the particular subject of castles in the UK are extremely connected, in deep ways that even after a fair amount of research, I still cannot fully explain.

Let me first start by exploring what castles were intended for in the first place. A castle was a powerful image that had a profound impact on the landscape- they were for military defense and protection, to reinforce status and social order, power, land consolidation, and for economic value. The people that lived in them, often the more socially elite lived a different life from those who peered in from the outside. Personally, I always compare it to how we look at celebrities now- we imagine their lives, their luxury, and what they do with their time, as it seems worlds apart from our own inner circle.
IMG_1024Castles were introduced in Great Britain and Ireland following the Norman invasion of England in 1066, and continued to grow in military sophistication and comfort during the 12th century. In Ireland and Wales, castle architecture continued to follow that of England, later moving towards the use of smaller tower houses. A classic example of a tower house is Eilean Donan, made famous for being the scenic backdrop for many films, including the first Highlander film and Elizabeth: The Golden Age. These two films are excellent, and I recommend them for their entertainment value!

By the 14th century castles were combining defenses with luxurious, sophisticated living arrangements and heavily landscaped gardens and parks. When I think of castles with lavish gardens and grounds, I always think of Dunrobin Castle in Scotland, one of my favorites. Their gardens in the back are terraced downwards, revealing a stunning ocean view and large lawns for the falconry demonstrations. Although the inner surviving keep is one of the oldest occupied houses in Scotland, the gardens were actually built during the Victorian period, and have not changed a tad since then.

By the 15th century only a few were maintained for defensive purposes. A small number of castles in England and Scotland were developed into Renaissance Era palaces that hosted lavish feasts and celebrations amid their elaborate architecture. Such structures were, however, beyond the means of all but royalty and the richest of the late-medieval barons. Although gunpowder weapons were used to defend castles from the late 14th century onwards it became clear during the 16th century that gunpowder would change the game of war. In the widespread civil and religious conflicts across the British Isles during the 1640s and 1650s, castles played a key role in England. Modern defenses were quickly built alongside existing medieval fortifications and, in many cases, castles successfully withstood more than one siege. Carlisle Castle in England is one example of a castle that was changed to accommodate canons.

Now that we have had a very rough whirlwind trip through the essential history of castles, I am now going to attempt to circle back to our original topic: how were they made, and what were they made of? You can see here where I got a bit off track in my research, and became stuck on the historical context rather than the castles themselves.

Initial Anglo-Saxon building in the UK cannibalized brick, tile, and stone from Roman buildings for construction until a more systematic industry of stone quarrying was instigated in the 11th and 12th centuries. Due to the varying geology across the UK, many of the building styles and traditions that developed over these periods were directly influenced by the kinds of rock available locally for building. Archaeological excavations of many castles have found temporary structures and workshops surrounding great hearths for forging and Lime kilns for lead and stone tile used on roofs. These can all be seen at Castle Sandal in West Yorkshire, when the castle was converted from a wood structure to a stone structure

Masons were responsible for the building of the majority of the castles built in the UK. They often lived a nomadic lifestyle, traveling from town to town looking for work. They would often apprentice as young children, and if talented enough would one day become a Master Mason. Masons would usually have a contract with a local Lord, who would provide the funds for the building materials and the man power for the construction. Construction of a castle would also require carpenters and blacksmiths. Blacksmiths would sharpen the Blacksmith_working.jpgmasonry tools every three days, and carpenters would build the scaffolding. It was hard work, and some projects would take a great portion of a lifetime to complete. They used simple tools, consisting mostly of a mallet, chisel, and straight edge. Chisels would come in varying sizes and shapes, depending on their function and purpose. Trowels were also used to place mortar around the stone to secure them in place. These hand tools do not seem like much, but it is amazing to see what is was that they built and how it has stood the test of time. Every mason would have a different mark that they would chisel into stone blocks and walls, almost like an early type of ‘quality assurance’ that they gave that structure or stone their seal of approval. They were a part of a huge and widespread industry, that is one of the world’s oldest trades in recorded history.

Every castle built during the Medieval period was uniquely built depending on several considerations, such as the terrain it was built on, the surrounding landscape, it’s overall purpose, the number of people it would support, and the wealth of the Nobles or Royalty who were building it. As we talked about earlier in history, their main initial purpose was defense. Most castles were usually built from a visual vantage point, such as a hill or mountain. UK geology has many natural features such as this in the landscape, such as Lindisfarne Castle pictured below. Castles also usually included an outer wall, a second lindisfarne castle.jpgline of defense, an inner wall, and a keep. Masons would draw a floor plan based on their extensive knowledge and needs of their employer, and get to work. And through the centuries these castles would often grow and change according to what their occupants needed.

I have never been especially interested in experimental archaeology, but in the case of castles it can lend a more practical view to how masons laid out their plans and constructed castles. We do not exactly have any medieval masons around that we can quiz about the building process! In England there exists one of the world largest ‘experimental’ archaeological sites, where a 25-year project to build a castle using only Medieval technology and resources is well underway. Sometimes, we can learn the most by trying to actually ‘do’. It would be impossible to anticipate how they would have solved problems unless we actually encounter the dilemma ourselves, right? About two years ago I watched a short series put out by the BBC about this project, and was absolutely fascinated by how they plotted out the construction of a spiral stair case using ochre coated string to ‘mark out’ the descent of the steps. Luckily they still had some of this online, which you can see by clicking here. It’s wonderful, please check it out!

One important thing to have nearby when building a castle, would be a quarry from which to source this stone for masonry. Lords, Barons, and even Kings would often fight over such valuable resources. Since the cost of importing stone was so high, builders often used what was immediately available geologically, be it chalk, pebbles, limestone, or sandstone. Through time, as structured were assembled and destroyed, builders would also recycle donnottar.jpgalready cut stone for new construction as well. Pictured below we have Dunnottar Castle in North East Scotland. Like most castles, Dunnottar was a ‘work in progress’ and was added to over many years with many building materials. The rock the Castle sits upon was forced to the surface 440 million years ago during the Silurian period. A red rock conglomerate with boulders up to 1m across known as Pudding Stone is incredibly durable. The Highland rock pebbles and cementing matter is so tough that faults or cracks pass through the pebbles themselves.

In the UK, three of some common building materials aside from those mentioned above, especially in Scotland were Carboniferous Limestone, Red Sandstone, and Granite. First up is Carboniferous Limestone, found in the Midlands of Scotland, a sedimentary rock composed of grains of marine organisms. Next is Sandstone, commonly seen in the city of Edinburgh today, a sedimentary rock that consists of quartz and feldspar. Last but not least is Granite, found in the rocky Northern Scotland and used for building in Aberdeen. Limestone, Sandstone, and Granite are still sourced and used today for modern buildings just as they were for the Medieval structures that still linger in the landscape today. I remember the first time I visited Edinburgh, the city was undertaking a major project to clean a lot of their sandstone buildings that had become blackened from air pollution with power washers. Sandstone although beautiful and readily available is extremely porous, and you can only imagine what it had absorbed over centuries of millions of coal fires burning!

A great example of a castle built from locally sourced sandstone is Carlisle Castle in England. Occupying a 4 acre piece of land, the castle is mostly constructed of grey and red sandstone, and its initial construction began in the 12th century. It is believed that the Romans initially quarried the Sandstone in the local area, but evidence of it has since been destroyed in the wake of massive removal for building since the Medieval period. Sandstone is light, and easier to transport, yet durable enough for construction. However, over time gravity causes it to settle, which might explain why many sandstone castles have needed reinforcement and constant upkeep over the centuries. Carlisle Castle was initially built to act as a home base for an invasion of Scotland, but became famous for acting as a prison for Mary Queen of Scots.

If you have found yourself particularly interested in any of the specific areas we have been talking about in this blog post, check out the British Geological Survey Website to learn more about the geologic makeup of the continent. They have a complete analysis of the bedrock geology which is fascinating!

Thanks for reading my strange conglomerate bit about castles. I suppose I pulled odds and ends form here and there that tickled my fancy when it was all said and done! Hopefully you also learned a new fun fact along the way.


Peace and long life.

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