Chances are if you think of an iconic Scottish building, it will be made of sandstone. Historically, it has been the main type of building stone in Scotland and was used in many architectural projects across Scotland – from Abbeys and castles, to tenement flats built to grow rapidly growing work forces as cities expanded. Many of the tenements found in Dundee would have been built using sandstone from local quarries that are no longer in use, including Carmyllie Quarry near Carnoustie and Kingoodie Quarry in Invergowrie. It varies in colour depending on where it has been mined – from deep rust coloured red sandstone, to light and creamy blonde sandstone.
As with all stone, sandstone is the product of millions of years of geological changes. It was formed from sand grains that were deposited by rivers, the sea, or the wind, which turned into solid, durable stone through millions of years of pressure, compaction, and heat.
Sandstone is naturally porous which can make it vulnerable to erosion over time as it’s subjected to water and wind, but if it is correctly maintained it is a building material with incredible longevity that will last for hundreds of years.
Location and Sources
Sandstone is predominantly located across the Central Belt of Scotland, including the Tayside region. The underlying rock in this area is predominantly ‘Old Red Sandstone’ sediments formed during the Devonian period around 400 million years ago. This can be seen particularly well in its natural form along the coast between Arbroath and Auchmithie where the cliffs are made from red sandstone. Stone quarried from the beach at the Seaton Cliffs in this area was used to build the historical Arbroath Abbey. The abbey fell into disuse after the Scottish Reformation in the 16th century and, over time, the stones used to construct it were removed and used to build new buildings around the town.
Quarries were once abundant and could be found across Scotland which mined and processed sandstone (and other stone) for local use. At their peak in the 19th century, there were thought to be around 2,500 building stone quarries across Scotland, although not all of these would have been producing sandstone. The colour of sandstone varies across the country, meaning that in many locations the buildings can be dated and the stone traced back to the mining site based on the colour.
There are currently very few quarries left in Scotland, and much of the sandstone used in Scotland is imported. But over the past couple of decades there have been a small number of historic quarries which have reopened across the country. These include:
Pitairlie Quarry in Monikie, outside Dundee, which reopened in 2004. It specialises in a grey sandstone with laminated, flag texture and low permeability.
Cullalo Quarry near Aberdour in Fife, which reopened in 2005. It specialises in a light hued sandstone that varies from ivory white to warm yellow.
It seems that many of the unused quarries across the country have now been turned into landfill sites, but some have turned into thriving nature reserves over time that now support a variety of wildlife.
Application and product output
Sandstone is predominantly used as an architectural building material. It can be used to construct the walls of buildings, in the restoration of historical buildings, as cladding on the outside (or indeed, inside) of buildings, and as a hardwearing flooring material.
Pitairlie sandstone, quarried outside Dundee, doesn’t have the properties required for use as a structural sandstone for buildings, but can be used as a non load bearing cladding material. It is ideal for dry stone dyking – a building method where walls are constructed from stones without the use of mortar, most commonly used for external structures like boundary walls. Notably, pitairlie sandstone was used to construct the Dundee Flood Wall which runs along the bank of the River Tay. It was also used in a 2010 restoration project at Acheson House in Edinburgh, which is one of very few buildings in the past 50 years to use indigenous Scottish stone as a roofing material. Pirairlie sandstone was used to make roofing slates, the like of which hadn’t been produced in over half a century.
Sandstone is also easily carved and takes texture well, so can be used to create decorative elements for buildings as well as ornamental features like fountains and sculptures.
Production and sustainable consumption
There are currently 14 sandstone quarries in operation across Scotland, 4 of which are in continuous operation. Between them, they produced an estimated 25,000 – 30,000 tonnes* of sandstone in 2015. Out of these active quarries, 6 have become active within the last 20 years – 5 of which are historical quarries which have been reopened.
Sandstone is a material which is abundantly available within Scotland, but difficult to access. The majority of sandstone used for building in the country is imported from overseas, but this comes with some significant considerations and environmental impacts.
In terms of sustainability, sandstone is a finite material but one which has a very long lifespan if maintained and cared for properly. This can be seen in many of the historic buildings within Scotland which have been constructed in sandstone 100+ years ago and are still in use. At the end of a buildings lifespan, the sandstone used to build it can be deconstructed and reused for other buildings provided a traditional lime mortar has been used, although the popularity of concrete over the past few decades has made this more difficult. Sandstone can also be recycled into aggregate for construction at the end of its life.
A major barrier facing the production of sandstone, and building stone in general, in Scotland is the lack of knowledge and skills needed to use these materials. The indigenous building stone industry in the country has been close to absent over much of the past century and this has led to a decline in the number of people who have the skills and knowledge to operate building stone quarries and to repair stonework in traditional buildings. This contributes to the decay of our historic buildings as the use of inappropriate materials (stone and mortar) in their repair and upkeep contributes and, in some cases accelerates, stonework decay.
(*Some of these quarries also produce siltstone, and the data available shows their overall output per quarry so there aren’t exact figures to show the output of sandstone alone.)
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