Geology and Quarrying in Mumbles by Ian Prothero

Summary

Quarrying has been recorded in Mumbles since at least the 17th century. Over the years great volumes of limestone have been removed for building, smelting and as an agricultural dressing. The material was exported to the West Country in a two-way trade in minerals, copper and tin coming to Swansea.

 

The quarry workers were also employed in the oyster fisheries and quarrying was the only industrial activity in Mumbles. Since the last site at Coltshill closed in the 1970s the former sites have become car parks, nature reserves and the headline banner to the beauty of Mumbles sea front.

 

This article is intended to link the geology of the Mumbles to its industrial history and present day landscape in a non-technical format.’

Introduction I write this short paper as an ex professional geologist with a strong interest in history and aim to keep it non-technical and hopefully spark an interest in Mumbles geology, and how it was exploited up to the near-historical past. Many residents of Mumbles live within a stone’s throw (or two) of a former quarry or limekiln. 

Technical terms are highlighted in bold blue are explained in the glossary. 

Fig. 1. From Thistleboon showing Coltshill and Clement’s Quarries. Pre 1877 (unattributed). 

To keep this paper to a reasonable length I am restricting the scope to the quarrying of limestone within the confines of Mumbles Head to Norton. 

Simplified Mumbles Geology cf. Fig. 2 

The oldest rocks in Mumbles are Lower Carboniferous Limestone deposited in warm tropical seas around 330 million years ago. This hard, grey rock forms the highland that surrounds the village from Oystermouth Castle around the top of Underhill Park and along Gilbertscliffe to Mumbles Hill and Mumbles Head. 

Overlying the limestone are softer sediments, mudstones and siltstones deposited before the Coal Measures proper as mined at Clyne. The marine sediments were deposited as roughly horizontal beds (strata) then folded and compressed into a U-shaped syncline, a pie-dish shaped trough. Most of the village running up on either side of Queens Road to Underhill Park lies on this flatter land. 

Fig. 2. British Geological Survey map of Oystermouth with author’s annotations

Quarries 

The Lidar map below highlights the known quarrying areas. Compare with the geology map above. 

Fig. 3. Bluesky Lidar Map of Oystermouth indicating known quarry sites 

Callencroft, Coltshill Quarries and the Gilbertscliffe Quarry along the north-east facing flank of Mumbles Hill exploited the Oxwich Head Limestone (OHL). It is light grey and hard. Sometimes crystalline calcite veins can be seen running through - these are the result of the heat and pressure and stresses of the orogenies. 

Quarries and limekilns flanking Underhill Park are seen on the 1877 OS map. Starting dates of quarries are difficult to determine, who extracted the first stone and when? A 1650 survey of Oystermouth states ‘The Lord hath a quarry of Limestone in the Common or Waste ground called the Mumbles Clift, which may be worth per annum about £10’ (OHA archives). Closing dates are approximate. 

Callencroft (closed late 1870s) and Gilbertscliffe Quarries Grid References (GR): O.S. Explorer map 164 Gower. Callencroft Main entrance: SS607881 and Gilbertscliffe: SS608879 These quarries comprised ‘massive’ (geology-speak for thick) beds of the Oxwich Head Limestone. 

Fig. 7. From the top of Underhill Park. Callencroft Quarry is out of shot to the left of the near-most cottage. Gilbertscliffe Quarry and limekiln would be behind-right. Late Victorian (Unattrib.) 

Studying satellite photos, it is probable that limestone was taken from the cliffs of what is now Oystermouth Cemetery not just Callencroft (now Peel Wood). In the 1920s the Miss Peels (direct descendants of Sir Robert Peel, founder of the London Police Force) lived in Sunnyside, just up Newton Road from the cemetery gates. The sisters owned a field on what is now Underhill Park. 

 

Coltshill Quarry GR: SS609883 (quarried until 1960s, closed late 1970s)

This is the quarry that I can find most information about thanks to Norman L. Thomas’s book, Mumbles Past and Present. It was the only consistent limestone producer in the 20th century and was known as the Norton Limestone Works (NLW). 

NLW was owned by Messrs. Bennet Brothers building contractors who built the second Oxford Street Market and was the only industrial employer in the Mumbles Ward in the inter-war years producing an estimated 20,000 tonnes a year and employing around 50 men.

The family bought two coal-fired asphalt plants and contributed to road laying in the borough between the wars. NLW produced limestone and took sand from the beach to lay the runways at Fairwood during WW2. Limestone although hard is not resistant to abrasion and its extraction from Coltshill for road laying was superseded by using post-industrial slag from the Swansea copper works – the ultimate in recycling.

Blasting was only allowed from dawn to dusk. It must have been a sensory overload with the rattle of plant, the crump of blasting with dust and smoke and fumes and flames from the limekilns.

Fig. 8. From Coltshill to Mumbles Hill. NB worker standing at the top of the limekiln. Operating a kiln was a highly skilled job. Early 1900s (OHA Archives) 

One eye witness who lived in the Castle Road area during and after the Second World War, in a house backing onto Oystermouth Castle remembers ‘lorries, noisy, rickety things, going back and forth up the slope to the works where they would dump their load of limestone. Where the modern estate is now was like a wilderness then. It was a big part of the daily life of those living adjacent. It was very noisy – with the rumbling of the rocks coming down.’ She doesn’t remember dust but her mother did not open the windows on the front of the house.

Fig. 10. From Coltshill Quarry. Note the coal pile in the centre. Undated (OHA Archives) 

Fig. 9 From Coltshill Quarry to Mumbles Hill. 1925 (OHA Archives) 

Another witness, Marion Garnett, grew up in the late 1940s in a house in Castle Road right opposite the lime kiln. She would be woken at 6.30am by the first lorry coming along the road, its lights shining into her bedroom at the front of the house. It would reverse into the little access road to the kiln; either side of the lorry were concrete stagings, as high as the top of the lorry. The lorry driver and his mate would then take it in turns to wheel-barrow the ‘rocks’ of lime from the kiln, along the concrete stagings and into the lorry. When it was loaded it departed and another would come along. Marion could see the red and orange glow at the back of the kiln in the early morning darkness.

 

The works operated from 6.30am until about 4.30pm – probably not at weekend when it was all locked up. As children they were not allowed anywhere near it, as it was too dangerous.  The site was well-protected with a high wall going right to the top – as high as the Castle – and a night watchman (who lived locally) came on duty about 8pm. When it was closed for the day all the white dust gave it very ghostly appearance.

Clement’s Quarry (commercially opened by Benjamin French at the turn of the 19th Century). GR: SS615883. In 1845 George Clement leased the site from the Duke of Beaufort. Beaufort also lent his name to the pub in Norton. There was also a Beaufort pub on Dickslade adjacent to The George.

Fig.11. An early photograph of The Dunns with Clements and Coltshill Quarries in the distance. Approx 1860s (OHA Archives) 

This is the geological exception of the Mumbles quarries; operations here removed the limestone and mudstone of the younger Oystermouth Formation (OLM) – the limestone has similar properties to the OHL. The mudstones are greyish-black, soft, and carbon rich and generally non-calcareous. This is perhaps the most exciting location for the geologist. These beds mark the final phase of carbonate deposition in South Wales in Carboniferous Limestone and is geologically very significant.

There are numerous fossils of corals and bivalves and brachiopods some of which can be spotted in the walls alongside the Tabernacle Church on Chapel Street and elsewhere. Where you see chunks of soft, black, crumbly stone in the local walls the chances they are from Clement’s Quarry. 

Fig. 12. Clement’s Quarry to Mumbles Hill. Note relatively thin strata. Early 1900s (OHA Archives) 

From a quarryman’s point of view the black, laminated and friable mudstone partings between the hard, grey limestone were a bonus. These allowed easy separation of the limestone beds and would have greatly reduced the amount and expense of dressing of the limestone blocks and made for much easier removal than the Oxwich Head Limestone from other Mumbles quarries.

Mumbles Hill: flanking Mumbles Road from Village Lane to Mumbles Head

We are back into OHL limestone. Looking at Fig 2. you can see a fault line running between Western Lane and Village Lane, this separates Mumbles Hill from the rest of the southern limb of the syncline that runs up the line of Overland road to Gilbertscliffe and Underhill Park. 

Much of the material removed here would have been burned in the limekilns to produce quicklime for use locally or as stone loaded onto smacks for export over to the West Country where it would have been burnt for lime and used for building or as an agricultural dressing.

During the mid 19thC Capt. George Phillips was landlord of The Ship & Castle pub (which went on to become the Conservative Club and now apartments). He also had a lease from the Duke of Beaufort to quarry outalong to the inner sound from Knab Rock to Bracelet Bay. Cf. Fig. 21

In 1850 an Inquiry was set up by Swansea Harbour Trust was held in Swansea Town Hall to investigate complaints of the effect of shoaling (shallowing of the sound) due to quarrying detritus and dumped ballast on the Mumbles Roads (the sheltered stretch of water used by ships at anchor).

Fig. 13. Quarried cliffs, beyond Southend. NB abandoned railway and The Knab. 1870s (OHA Archive) 

Fig. 14. Southend. Loading ramps and stone. Note the oyster skiffs to sea. Pre 1888 (OHA Archive).  

The returning ships from Devon and Cornwall would have carried produce including Cornish tin and copper but also ballast. Being the over-observant geologist that I am I noticed that an exposed wall in the restaurant at 698 Mumbles Road (currently La Dolce Vita) shows xenoliths - ‘foreign stones’, definitely not Gower sourced – I strongly suspect their original home was Cornwall.

Uses of The Quarried Limestone: Limestone is so diverse in its uses, including:

Buildings: 

This limestone had a variety of uses the most obvious is construction. Oystermouth Castle which was rebuilt in stone by the de Breos family in the late 13th Century certainly using stone from the site of Clement’s and possibly Coltshill quarries. The castles stones would have been plundered in turn for local building. The castle, perched on an easily defended hill with a good vista to track potential trouble – most castles are. Building on a high point also imposes on local inhabitants - great psychology.

Fig. 15. Oystermouth Castle views from what is now Castle Avenue (M A Clare) 

Before the ubiquitous cheap brick, spurred on by Victorian rail transport, buildings were constructed of local material. The old Antelope pub (in the middle of an extended refurbishment at the time of writing) at the foot of Village Lane used Oxwich Head Limestone, probably quarried within spitting distance.

Mortar is produced from limestone (or preferably dolomite, a magnesium enriched limestone) that has been skilfully calcinated in a lime kiln to produce quicklime. The quicklime is slaked with water to produce cement – the essential building, also mortar, render, concrete, whitewash and distemper – a house could be built and finished from one quarry (and a few trees!).

Mumbles Marble

This was a decorative stone (not actually a true marble) when it was polished it produced an attractive, grey stone with calcite veining, probably sourced from Coltshill.The stone was taken to The Cambrian Marble Works, at the mouth of Washinglake Brook, immediately to the north of the present-day West Cross Inn. It was used for features such as fireplaces and mantlepieces – great for fitting out your recently built house. I have wondered whether this use of local decorative stones became prevalent due to reduced access to marble imports from Europe during the Napoleonic Wars.

Fig. 17. The Antelope Hotel 2021 (Author) 

Fig. 18. The Antelope. Detail showing an xenolith of cross-bedded Old Red Sandstone, probably from Devon. Note also original mortar (Author) 

Smelting:

Limestone is used to remove impurities from the blast furnace when extracting metals such as tin, copper and iron from the ore. The calcium carbonate reacts with the silicon dioxide (sand) to form calcium silicate also known as slag. Slag was also used as a building material in Mumbles and Swansea – that is another story. Copper and tin smelting were hugely important Swansea industries.

Agricultural Lime 

Limekilns would have been dotted all around the quarries, they are still extant at Peel Wood (apparently), on the junction of Castle and Limekiln Roads and the Knab Rock Car Park.  

Burnt limestone was used to reduce the acidity of soils and increase the calcium and magnesium. This was only reasonable if there was cheap coal (Clyne Valley) and an accessible market – in prerailway Britain Bideford, Devon was only a hop across the channel and with Cornwall was actively linked with Mumbles.

Fig. 19. Schematic of typical limekiln and its Coltshill equivalent + 21C detritus. Lime burning needed highly skilled operators (Unattrib. and author) 

The Swansea Valley industries produced acid rain affecting the pH of the soil, this was mitigated by dressing the fields with lime.

Transport: 

The Mumbles Road: The Yates Map of 1799 shows no road along the foreshore (there probably would have been a basic track or footpath), the route wriggled around the back from Mayals via Norton and to Dunns Lane so the construction of the tramroad was truly a ground breaker. The road then extended to the foot of village lane. Further access along Mumbles Hill would be by footpath or boat, Southend being a discrete village with its own post office (OS Map 1877). By 1890 the road had been extended to Southend and ‘the cutting’ to Bracelet Bay was completed

 

Mumbles Tramroad: laid from 1804 to 1806 during the Napoleonic Wars. It was intended for carrying limestone from Oystermouth to Swansea and coal from Clyne to Swansea and Mumbles. In 1807 it became the world’s first passenger carrying railway. By 1893 it extended to Southend and to the newly finished pier by 1898. Mumbles was now a tourist destination open to one and all.

Legacy

After generations of quarrying and lime burning what were the consequences? 

 

Callencroft and Gilbertscliffe Quarries: closed in the late 1870s becoming part of the Oystermouth Cemetery, the first burial was in 1883. The cemetery has been extended towards Coltshill including a green burial site. The freehold was bequeathed to the Wildlife Trust by Mrs S.M. Peel after her death in April 1979. It is now Peel Wood Nature Reserve. Callencroft Court now occupies the site of the family home. Gilbertscliffe is now woodland overlooking Underhill Park

Coltshill: back-filled in with rubble now a small housing estate. The curve of Waverley Drive reflects the back end of the quarry site - home to a much-appreciated OHA committee member

Clement’s: a car park; SSSI, Potential Regionally Important Geological and Geomorphological (Geodiversity) Site (RIGS) of priority interest.  

Mumbles Hill: Local Nature Reserve; potential RIGS sites of priority interest. The Cut, running through to Limeslade, was once a source of ironstone (haematite), it is clearly marked on the older OS maps. It was backfilled in part with rubble from constructing ‘the cut’ road and from the excavation, in the 1920s to 1930s, of the huge caverns used for sewage storage (part of the Swansea Main Drainage Scheme 1931 -1936).

Fig. 20. From Mumbles Hill to Oystermouth. Cemetery on the mid-hill crest. Present day (Author) 

The Copperfish restaurant and the old, classy night club Cinderella’s buildings now occupy an old quarry site, the adjacent beach is there thanks to limestone extraction.

Fig. 21. Quarry and beach at Inner Sound, Southend. PD (Author) 

Mumbles Employment: The quarries were not necessarily worked throughout the year. The workers would have also been employed dressing the stone and working seasonally on the oyster fisheries. The quarried stone for export was carried by barrow or horse-drawn cart on to the beach piled up by men, women and children. In the spring it was loaded on to smacks via bespoke stages for export.

The spin-off income would have kept services including shops, smithies for dressing tools and shoeing horses, schools for the mind, pubs to whet the whistle, clubs, chapels and churches for the soul.

Immigration / Emigration: John Vivian, a quarry owner and copper smelter, came over from Truro, Cornwall before 1800, he and his family went on to set up Hafod Smelting Works and built both Clyne Castle and Singleton Abbey. Another Devon family, the well-known Aces became the lighthouse keepers. Migration was a two-way traffic, Welsh miners migrated to Cornwall to work in the tin and copper mines. The old Mumbles dialect was known for its West Country influences.

Fig. 14. Southend: Men loading stone with horse & cart (and dog). (Thanks to Stuart Bishop & HoM) 

Biodiversity: The former quarries and cliff lines now provide a diverse habitat web of mixed, deciduous woodland supporting a great range of wildlife from top predators such as foxes and sparrowhawks, rarely a couple of peregrine falcons have been seen; through to bats and hedgehogs to the tiniest bugs and microbes. 

The range of plant life is vast, from beech trees to mosses, and the harbinger of Gower spring - the alkali soil loving wild garlic. Lichens indicate the purity of the gentle sea breezes that occasionally lap the village. The cliff line is truly a wildlife corridor.

Discarded Stone on The Foreshore: What look like random piles of stone can be seen in the intertidal zone between Blackpill and Mumbles. Carol Powell has described similar artefacts on Caswell Bay exposed after storms. Some would have been ballast, some perhaps, just abandoned.

Fig. 22. Discarded ballast (hull shaped?), Caswell Bay. Exposed after 2014 storms (J. Powell, AHoM) 

Conclusion: 

Over the centuries a huge volume of Carboniferous Limestone was extracted from local quarries and used in any numbers of ways from agriculture dressing, building stone and smelting. Its export to the West Country led to an import of innovators who helped kickstart Swansea’s industrial revolution. The former quarry sites are now covered in homes, sand and semi-wild areas – homes to much life in Mumbles. 


Glossary

 Carboniferous From around 359 to 299Ma. This geological period was a time of warm, tropical seas, as time progressed and sea levels dropped giant rivers with swamp-loving vegetation formed coal – the heart of South Wales industry

 Devonian (Old Red Sandstone) Spanned from 419Ma to 359Ma. What is now Wales was part of the continent Laurasia, a desert environment with an arid climate. Red Devonian rocks form the core of the Gower anticline exposed at Rhosili and Cefn Bryn 

Limestone Rock made up of predominantly calcium carbonate – Ca CO3 

Syncline a ‘U’ shaped fold in sedimentary rock strata 

Anticline an ‘n’ shaped fold in sedimentary rock strata 

Orogeny a period of mountain building 

Fault an extended break or relative displacement of rock beds 

Strata / bed a layer or layers of sedimentary rock. Stratigraphy is the study of strata 

Lidar measures distances by illuminating the target with laser light, commonly used to make high-resolution maps as it ‘erases’ trees and shrubs from the image 

References 

Minerva: The Swansea History Journal 

Norman L Thomas, The Mumbles-Past and Present, 1978 

Gerald Gabb, The Story of the Village of Mumbles, 1986 

Brian E Davies, Mumbles and Gower Pubs, 2006 

Glanmor Williams (Ed.) Swansea An Illustrated History, 1990 

 Illustrations 

The majority where sourced from the OHA archives and AHoM website with thanks to Stuart Bishop. Others, uncredited, have been lifted from the internet. Many thanks to the copyright holders and apologies if I have trodden on any toes. If they contact me will be happy to acknowledge them in future as needed. The photographs have given me a huge amount of pleasure.

I have also plundered work by the local historical aces who contributed to Carol and John Powell’s website - A History of Mumbles (AHoM). John and Carol also provided some excellent photos from their collection also from the collection of Stuart Bishop. Thanks to Matt Hunter wildlife information.

Acknowledgements 

Thanks to Frank Rott of OHA for proposing this topic early in the first lockdown. Credit and huge thanks to Kate Jones for her advice, editing and critical skills also the lovely interviews with two ex-residents of Castle Road near the limekilns also to Gerald Gabb, Swansea History Journal for corrections and tips. Credit to John and Carol Powell also – there may be another paper …

None of my work is from first hand sources so I stand on the shoulders of others. Any mistakes and omissions are my responsibility