Limestone: quicklime, tubs and ghostly kilns

At Wardhall kilns

This blogpost is part of my ‘limestone lockdown’ project. For an Introduction to the project, and a guide to the growing list of related posts, see Limestone in the Lake District: an Introduction – and the ‘categories’ list in the right-hand bar.

Lime kilns are a feature of limestone country. Many are small, and slotted into hillsides and escarpments like eyes in a skull, their brows an arch of brick or stone. Others are taller more imposing stone-built structures, sometimes with fancy arches. Older, simpler versions like clamp kilns, dug into a slope and formerly turf-covered, may be harder to recognise; the wide variety of designs of kilns of all ages and types is comprehensively discussed by David Johnson [1 – book and video], and David Kitching’s website [2] lists details of many Cumbrian kilns.

But all are used for ‘burning’ – or more accurately calcining – limestone, to give quicklime. Quicklime, slaked lime – words for altered limestone that tell different stories, and bring back remembrance of chemistry lessons. If limestone (calcium carbonate, CaCO3), is heated, carbon dioxide (CO2) is driven off to leave calcium oxide (CaO); this is quicklime or burnt lime, a crystalline, alkaline and caustic substance, that is used for dressing pastures [3], and in the steel-making process [4], and – if water is added to convert it to slaked lime (calcium hydroxide, Ca(OH)2) – for making plaster and mortar [5].

Calcining requires the stone to be heated to between 600 to 1200oC, depending on the type of kiln, and in the earlier types of kiln this was achieved by burning wood or gorse or peat; later, coal or coke was used, and in modern times the fuel is gas. Fuel and stone might be tipped in from the top, separately or sandwiched; the firing might be fairly continuous or intermittent; as Johnson explains, there was often a degree of flexibility. The outcome, however, was the removal of quicklime from the bottom. The surprising result is that if lumps of stone are fed into the kiln, lumps of stone – albeit about 40% lighter since CO2 and any moisture have been driven off – are removed as quicklime, and usually need to be crushed before use.

Continuous use of fields for crops removes nutrients and gradually increases the acidity of the soil, and decreases the fertility. The (alkaline) quicklime from the small field or estate kilns was probably used locally either for spreading on arable fields and pastures to improve the productivity of the land [3], or as a building material, but there are several majestically large commercial kilns whose origins were closely linked with not only the West Cumberland coalfields but also the large deposits of haematite or iron ore in the West of the county. Near where I live and well-hidden from public view are the Wardhall – or Warthole – limekilns.

The track to the kilns runs straight, sloping gently downhill towards the River Ellen. It’s January 2021 and the fields are full of chocolate-brown Herdwick hoggs with white legs and faces, brought down from the fell farms to over-winter on the richer lowland pastures. In the way of Herdwicks, three of the young sheep have escaped and are browsing on the brambles along the track; they stare at us and, knowing they are doing wrong, sheepishly sidle back into their field, remembering exactly where the fence is broken.

The track is firm underfoot and runs for nearly a mile, lined on each side by tall flailed hedges of hawthorn, ash and elder that limit the view. Then suddenly we are out, onto a flat area, glistening with ice and green with moss, that is raised above the river valley like a belvedere. There is an unconvincing rusty-wire fence at the abrupt edge – and a steep vertical drop, a cliff-face of dressed sandstone blocks. Although it’s impossible from here to tell, we’re on top of the kilns and, although they are now covered over, we’re standing on the entrances to the pots into which limestone and fuel – coal – would have been tipped.

We back-track to a strip of damp woodland beside the track, and scramble down a bank, through brambles and the stalks and flat dry heads of cow parsley, frost-rimed; clamber down a low brick wall onto what might have been a platform or loading area, and then onto a plain of straggling grass and shallow moss-filled pools overlying rubble and broken brick. Now we’re at the base of the enormous flat front of the bank of kilns. The entrances to the four pots are like half-bottles, each framed in perfectly-cut and aligned sandstone blocks. The interior walls are dank with green algae and liverworts, and partly-hidden by ivy.

Scrubby, boggy ground and straggling ash trees make reaching the openings difficult – but at the back of each deep arch are small brick-edged rectangular openings, supported by rusting metal. One is still partly closed by horizontal iron doors. These are the draw-arches, from which the quick lime would have been raked out of the fire-pots, probably straight onto waiting railway-wagons. The arches are now blocked, one by horizontal rusty iron doors; another by a solid tumble of grey and black stones. From two others, spectral effusions of white, streaked limestone ooze out – slow waves of calcium carbonate re-petrified – decorated with the jagged teeth of stalactites. Within the massive stone structure, the hidden pots of the kilns still contain limestone – through which water has trickled down, dissolving the calcium salts, the concentrated brine seeping out year after year.

When lime-burning first started here isn’t clear, but Graham Brooks, in his research into Cumbrian limekilns [3,6] states that the Warthole kilns, “were rented out to both the Gilcrux colliery company prior to 1852 when they were advertised to be let by Mr Richardson of Dovenby Hall. (The present kilns probably date to after this time.) The Solway Haematite Iron Company, Maryport worked the quarries and kilns in the 1870s.”

In other words, the 19th century limeworks were associated with companies that dealt with coal and with iron ore, haematite – so the quicklime would have been used in the production of iron. If haematite is heated to high temperatures, molten iron is liberated – and the quicklime bonds with the impurities from the fuel (coal) and the stone to form slag, which floats on top of the molten metal [4,7].

Maryport & Carlisle Railway: By Afterbrunel – Own work, CC BY-SA 4.0, Commons Wikimedia

This was also the age of railway building, especially in Cumberland. Between 1840 and 1845, the railway from the coastal town of Maryport to Carlisle in the North was completed, and the section from Maryport to the coal-mines at Arkleby (very close to Wardhall) was finished in July 1840 [8].

Warthole quarry, 25-inch OS map extract
Warthole quarry, 25-inch OS map extract

The 25-inch Ordnance Survey map for 1865 [9] clearly shows the Maryport & Carlisle Railway (M&CR) running alongside the River Ellen, with sidings that connect with a fan of four lines from the Warthole Limeworks (where, curiously, only three – not four – pots are shown). The OS map also shows the track that brought the limestone down from Warthole Quarry, to the South-East of Warthole Guards Farm – this was the sloping inclined plane or tramway, down which rope-linked tubs laden with stone would pass, and down which we had walked between the wintry hedges. Gravity ensured the tubs would reach the flat area at the top of the kilns and, as they rumbled down the rails, their weight would pull a train of empty tubs back up to the top; the double line of rails midway acted as a passing place. Rails fan out to the rock-faces in the quarry, too. The deep quarry is still there, now partly obscured by a tangle of trees and vegetation.

But by the time the OS map was revised in 1891 [10] the M&CR sidings have been removed; Ward Hall Limeworks are marked as Disused, and the tramway is marked as ‘Old Wagonway’; there are no longer rails for tubs in the ‘Disused’ quarry. Iron and steel production was still centred on Workington, but cheaper iron ore was being imported from Spain and the economics of transport were changing rapidly [11]; the M&CR’s Arkleby station was closed, and the Solway Junction Railway that carried haematite across the Solway Firth to Scotland would soon be closed.

Interestingly, the 2007 obituary of Donnie Bewick (12), a former neighbour of ours, notes that “During the war, Donnie drove for Gilcrux hauliers, Johnston Bros, many times leading lime into Scotland from Warthole limeworks, Plumbland.” Curiously, this implies that the kilns might have still been working – ‘lime’ usually refers to quicklime, limestone to the rock itself.

Here, then, is another lost story. There will surely still be local memories, some of which might go back a couple of generations. Further details of the stories must wait.

1. David Johnson (2018) Lime Kilns. History and Heritage. Amberley.

          2021 ‘Lifting the Lid. Excavation of an early limekiln at Pendragon Castle.’ A video in the Westmorland Dales series of webinars, https://vimeo.com/513514308

2. David Kitching’s website. http://www.brocross.com/industrial%20history/cumbria%20limekilns/cumbria%20limekilns_files/cumbria%20limekilns.htm;

3. Graham Brooks’ website  http://www.solwaypast.co.uk/index.php/structures-in-stone/2-uncategorised/14-cumbrianolway)

4. Ann Lingard (2015) Volcanoes of Workington, blog-post https://solwayshorewalker.co.uk/2015/07/16/the-volcanoes-of-workington/

5. Ann Lingard (2017) What’s a clay dabbin? Blog-post https://solwayshorewalker.co.uk/2017/05/05/whats-a-clay-dabbin/

And ‘Hot mix: lime plaster’ Blog-post – due shortly

6. My thanks to Graham Brooks for his email discussions, and for further information on his website http://www.solwaypast.co.uk/index.php/structures-in-stone/7-limekilns/35-wardhall

7. https://britishlime.org/technical/iron_and_steel.php

8. https://en.wikipedia.org/wiki/Maryport_and_Carlisle_Railway; map by Afterbrunel – Own work, CC BY-SA 4.0, Wikimedia Commons

9. https://maps.nls.uk/view/121142384

10. https://maps.nls.uk/view/101091244

11. Ann Lingard & James Smith (2017) Crossing the Moss, Bowness Common and the Solway Junction Railway https://crossingthemoss.wordpress.com/

12. https://www.whitehavennews.co.uk/news/17166976.donald-donnie-berwick/

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