Great British Stone: The stone beneath our feet

Last month, Barry Hunt began a series looking at some of the building stones of the British Isles that have been used over the centuries and continue to be used today to maintain and expand the built heritage of these islands. Last time he looked at what he argued could be considered the greatest of all British stones: Portland. This month he looks at some other stones that might be considered great British stones.

What makes a British stone great? I would wager that there would be many and varied answers to this question from different perceptions. A scientist might proffer one of the Scottish or Cornish granites because of their strength and durability. An artist might select a decorative stone such as Ledmore marble. A mason could pick any one of the many softer freestones due to their ease of use. The so-called ‘man in the street’ might not even have a name to give, or might offer up Stonehenge or one of the great historical sites or stately homes.

There is no doubt that a number of British stones have a greater reputation than others and it would seem there is no definitive or easy answer as to why this should be the case. So let’s have a look at some of the factors and how best to establish what might be considered to constitute the Great British stones.

London is a good place to start our search as it does not have any usable stone materials of its own. It is a muddy bog, really. The surrounding area for quite some distance is also bereft of stone, which is why the city was largely built of wood until the Great Fire of 1666 changed people’s attitude towards building in wood.

Yes, there are some gnarly flint materials around London and at the fringes we hit the chalk and a bit of puddingstone. Then there are minerals such as Reigate stone, but these are neither ubiquitous nor easy to extract and use for building. So any stone that makes it to London and then becomes widely used has to be special, doesn’t it?

Yes, it does. But it may be special due to being located near the coast and easy to ship. This is one of the reasons why the White Tower at the centre of the Tower of London was built using mostly Caen stone from Normandy in France. Aside from the fact that William the Conqueror’s family owned the Caen quarry and he preferred to use French stone for structures he intended to demonstrate his dominance rather than ‘Saxon’ stone, the Caen stone could easily be taken in bulk as ballast across the English Channel and up the Thames.

A thousand years earlier, the Romans had built the walls of Londinium using mostly Kentish Ragstone, probably because Watling Street, that ran through Kent from Dover to London, allowed the stone from Kent to be moved in sufficient bulk to be used for building in London – a feat that had been impossible before Watling Street was constructed through the marshes and forests of that time.

Even so, in South East England the Romans left mostly a legacy of terracotta, bricks and mortar, thanks to the clays they found readily available, but wherever they could they built using the stones the ground beneath their feet offered them.

It is no coincidence that many of the great roman towns in Britain – Aquae Sulis (Bath), Eboracum (York), Deva (Chester) – all have a long history of stone use.

The foundations for stone working in Britain were, quite literally, laid in these and many other towns and villages, creating a legacy that, in most instances, continues to the present day.

But it is those stones that went beyond regional use that are of most interest – stones that developed from being provincial building materials to materials used on some of the most significant of the country’s buildings.

We saw last month (NSS May issue) the impact that Portland stone has had on the character of the built environment of London. But why did stones from the York area end up as paving all over London – and, indeed, many other parts of the country? And what is it about Dartmoor granite that makes it the material of choice for kerb stones?

There are many other stones I could mention and all have a history attached to them. I want to address a number of these stones over the following issues of Natural Stone Specialist and explain more about their properties and how they should be used in construction.

London’s history of stone use crawled along slowly as the roman roads fell into disrepair. It is no coincidence that even by as late as the 17th century there were relatively few stone buildings in such a major European city. Many buildings remained stubbornly wood-based, with brick or wattle and daub completing the walls. It is why The Great Fire of 1666 was able to take hold with such devastation and so little of the city today dates from before the fire.

After the fire came a time of change, with the new St Paul’s Cathedral rising from the ashes as a statement of intent for the new London.

With it, Christopher Wren set the trend for building in London that has lasted to the present day… a trend set in stone – and the stone was, of course, Portland.

Wren was reportedly a frequent visitor to the quarries on the island of Portland in Dorset in order to select the stone he wanted to use personally. And he was given a legal right to priority for the stone.

At that time there were coastal quarries from which the stone could be lowered into boats and, like the Caen stone, it was relatively straightforward to transport it around the coast and up the Thames.

There were 51 more new churches constructed in London around this time and soon after to designs from the office of Wren (which included the famous Hawksmoor churches). Those following in Wren’s footsteps chose the same stone as Wren had used.

Although there are peculiarities that are not built of Portland limestone – notably the Houses of Parliament – so many of the great buildings of London do use the stone that it can be said to be one of the defining elements of the city. That is why Portland limestone kicked off this series and was the first stone to be dissected.

Of course, most stones were not used much outside of the areas they were found. Some marbles, granites and more exotic stones were considered of high enough value to make it worth transporting them, but more commonly occurring sandstones and limestones were mostly used close to where they were found.

The building of canals led to the transport of some stones to a wider area. But it was not until the age of the train that most stones had much hope of making an impact further afield because it was just too impractical to transport them before that.

The steam engine was one of the great driving forces of the Industrial Revolution, providing the power not only for locomotion but also for the burgeoning factories and pumps of the coalmines.

But it was the railways that facilitated the transport of bulky, heavy goods overland. It was partially, at least, a marketing promotion that the railway companies built their London terminals with materials they had brought in from sources far from the capital.

Those terminals often had great hotels attached to them. The magnificent St Pancras Station was commissioned by the Midland Railway to rectify the fact that it had no route of its own into the capital. The station opened in 1868 and the Midland Grand Hotel attached to it, which opened five years after the station, was a Victorian Gothic masterpiece designed by Sir George Gilbert Scott.

Although primarily of red clay brick there was extensive use of stones from Derbyshire (Mansfield Red), Lincolnshire (Ancaster and Ketton limestones), Cumbria (Shap granite) and Aberdeenshire (Peterhead granite). Swithland slate from Leicestershire was used for the great expanse of roofs, the quarry being owned by John Ellis, the Chairman of the Midland Railway at that time.

The railways effectively helped other quarriers to serve notice on the Portland stone quarries that they were now in real competition with the rest of the country for the face of London.

The move from ships to railways to transport heavy goods engendered a fledgling use of granite for road cobbles in London, although this rapidly waned due to the development of tarmacadam surfaces.

One area that has remained stubbornly stone-led to this day is pedestrian paving… and the epitome of paving is York sandstone, although these days sandstones from India and China are often substituted because they are less expensive.

York stone was ubiquitous in the North of England. It is a major part of the Pennine rock sequence that forms the backbone of the British Isles. Now, almost every town and city centre and many gardens and houses around the country have some form of York stone paving or walling somewhere.

However, York stone is possibly one of the most misunderstood stone classifications as it refers to a poorly defined region where there is actually a huge variety of stone available. This region includes many stones from the surrounding counties (Derbyshire and Lancashire), which have similar appearance and properties because they are geologically from contemporaneous rock sequences.

This confusion of geography has proved difficult to address. York stone, more than most others, has quietly entered the national consciousness and for this reason alone should be regarded as a truly great British stone. The controversy of classification will be one of the issues I discuss when I deal with York stone in more detail in this series.

Although I have demonstrated my London-centric view by concentrating on the development of stone use in London, many of these comments apply just as well to other cities around the UK.

We see that most cities are typically dominated by one or two stones – stones that are typically locally won. Many cities also have particularly important buildings built in imported stones, quite often Portland, as provincial elites tried to demonstrate their urbanity and importance by emulating the styles of London.

The economies and supporting infrastructure of other cities compared with London are often far less developed and the variety of stone use is typically significantly more limited, but still we can see that stone has been imported.

Nevertheless, the predominant use of more local stones has allowed different cities to obtain and retain a character of their own. So someone living in one of the larger cities, or maybe a region such as the Cotswolds, may rightly think that their local stone is great.

It is illuminating to ask a visitor to our shores what British stones they think are truly great. More often than not, the answer will be: Welsh slate. It has a truly international reputation.

Here is a stone that defines a whole country, it would seem. Although coal is a stone that may challenge such a bold statement, it is a far less romantic proposition.

The reason Welsh slate has had such an impact is that it has been shipped around the world. And what made it worth shipping round the world are its exceptional properties. The best quality Welsh slates are difficult to fault. They provide the perfect roofing material that can give centuries of use on a properly constructed and maintained roof. This may be the one natural stone that ultimately is the most readily identifiable to that aforementioned man in the street wherever the street is in the world. It can, therefore, justifiably claim to be regarded as truly great.

But Wales is not the only region to produce slate. Possibly running second to Welsh slate are the Cumbrian slates that include Westmoreland Green and Burlington Blue, which have been exported across the globe as slabs for flooring and cladding as well as roofing slates.

I have to declare an interest at this point as these are my personal favourites because of their colour and texture. The Cumbrian slates have also usurped Welsh slates as the material of choice for the roofing of some of the most highly desirable residences – not because they were any better but because they appeared to be more exclusive, with a more restricted supply and, therefore, higher price… but you do not give away beautiful stone.

For the wider stone industry it is fortunate that architects and designers of buildings like to stamp their mark on the world. Their desire to do so has promoted the use of an ever-increasing variety of stone from both home and abroad.

In the current economic climate it can be difficult for stone won from UK quarries and mines to compete on price with stones quarried, processed and transported from the far corners of the earth, where labour and other costs are far lower (even if such low costs are at the expense of health & safety and other ethical considerations for workers).

British stones can also struggle to compete with lively, colourful marbles, granites and more exotic stones from around the world where a statement of that nature is to be made.

With so much stone for customers to choose from it is harder for British stone to stand out from the rest and be regarded as a true great among natural stones. Thus we are now at an impasse where we have to

re-evaluate the criteria for establishing which are the great British stones.

There are many stones from the UK that perform as well if not better than the stones that have so far been suggested as great. So are they also great?

Life can’t be that simple, unfortunately. It may be down to geological (and other) factors that restrict more widespread use of a stone. Bed heights might be shallow, block sizes small, supply limited. The stone might be buried below great depths of overburden. There might be weathering patterns, jointing, faults… so the list goes on.

One other stone that has a long and distinguished history of widespread use is Purbeck Marble. It is one of the British stones that can take a high polish and has been considered worth giving that polish in order for it to be used for decorative purposes.

It turns up in many major churches and cathedrals and its use goes back to the Romans, who recognised it for its decorative properties. Its occurrence in the quarries of Purbeck is extremely rare, which means it cannot be regularly quarried. Nevertheless, it is still prized for statuary and decorative stonework and through the ages has overcome considerable adversity to find its way around the country in times when this would have been exceptionally difficult. That alone makes this one of the great British stones of history.

Really, I think every British stone is great. In fact, it is not even just British stone that I think is great – even some that is frequently ignored and seldom used, often largely simply because it is poorly understood.

And we are now adopting building regulations that require such high levels of thermal efficiency that they seem to threaten to force us to stop using stone for external envelopes… certainly in the traditional way (although already new ways of using insulation are offering solutions to such problems). If the use of stone were to become redundant, the character of many areas would be smothered with dullness. We need to support our great British stones, although we need to understand them a little better in order to be able to do so.

In the coming months I shall be looking more closely at all the stones mentioned in this article and more. I will remain open to suggestions from readers about what they believe to be a great British stone and why, so do send me a note of any stone you think should be included with a line or two explaining why (send an email to me, Barry Hunt, at [email protected] or [email protected]).

I am sure there will be support for stones such as Bath limestone. And what about Clipsham, which has been used to replace the rather poorly performing Anston limestone used for the Clock Tower and elsewhere at the Houses of Parliament? DeLank granite must be a contender, surely? There are literally hundreds of stones to choose from. With some help from you (I hope), I will make a case for those I select in the coming issues of Natural Stone Specialist that can truly be considered among the greats of Great Britain’s stones.

The author: Barry Hunt

Barry Hunt is a chartered geologist, a surveyor and scientist. He has been awarded the designation of European Geologist and is a Corporate Building, Conservation and Specialist Surveyor. He is also a Member of the Chartered Institute of Building and a Fellow of the Royal Microscopical Society.

Barry has served on a number of professional committees, including the Technical Committee of Stone Federation Great Britain (SFGB), which provides advice on all stone construction issues. He is one of the authors of the SFGB team that has published codes of practice for the installation of stone floors and internal stone finishes.

Barry gained 14 years’ experience working as a consultant for two renowned civil engineering materials consultancies before, in 2001, establishing his own consultancy, IBIS, specialising in the investigation of construction materials.

The specialist knowledge and services provided by Barry have allowed him to be instrumental in the resolution of problems ranging from blast damaged claddings in London’s West End to advice on the quarrying and extraction of stone from abroad for import to the UK. Other areas of experience include the investigation of all types of building finishes, specialist advice on remedial treatments and the preparation of advice for potential and actual use in litigation or arbitration.

Having worked for consultancies that both undertook in-house laboratory investigation to UKAS requirements, Barry is also able to conduct or oversee a wide range of on-site and laboratory techniques and ensure they are carried out to traceable standards.

One speciality in all investigations is Barry’s hands-on approach. Being trained in industrial roped access (abseiling) allows him to get close to the problems with external building envelopes quickly, efficiently and cost-effectively.

Throughout his working life Barry has published findings from the many investigations he has undertaken. He has also authored chapters for two books on building stone and is currently engaged in other book projects in this field. His most important contribution is considered to be the chapter on the repair and maintenance of stone in the landmark Geological Society publication Stone.

Barry is also a regular contributor, covering the full spectrum of natural stone use, for Natural Stone Specialist magazine.