Derbyshire Caving Club – Special Report 2012
National Association of Mining History Organisations
Proceedings of the Annual Conference 2012
Quarry Bank Mill, Cheshire
29th June to 1st July 2012
Cover illustrations:
West Mine, Alderley Edge in Paul Deakin photographing 1923 in a N Staffs coal mine
Joy continuous miner in Pott Shrigley fireclay and Boulby potash mine (PRD) coal mining area
Proceedings of the 2012 Annual NAMHO Conference Contents
1 INTRODUCTION 3 2 LECTURES 4 3 TRIPS (SURFACE AND UNDERGROUND) 5 3.1 Alderley Edge mines 5 3.2 Alderley Edge surface 6 3.3 Apedale heritage centre and coal mine 6 3.4 Astley Green colliery 7 3.5 Chatterley Whitfield colliery 7 3.6 Ecton copper mine 7 3.7 Goodluck lead mine 7 3.8 Hanging Flat barite mine 8 3.9 Pott Shrigley surface 8 3.10 Poynton surface 8 3.11 Winsford salt mine 8 4 SUMMARIES OF LECTURES 9 4.1 Alderley Edge and related topics 9 4.2 Salt and potash mining 10 4.3 Coal mining in Cheshire and North Staffordshire 11 4.4 Metal mining in Derbyshire and Staffordshire 11 4.5 Other subjects 11 5 PAPERS 13 5.1 Poynton Collieries, a brief history – David Kitching 13 5.2 Mining archaeology of a 19th-20th century lignite deep mine at Kausche, Lower Lusatia – Martin Straßburger 14 5.3 Alderley Edge 1857-1877 – Nigel Dibben 15 5.4 Mining techniques through the ages at Alderley Edge – Pete Johnson 17 5.5 Goodluck Mine, Derbyshire – David Barrie 18 5.6 Geology, Mineralisation and Metal Mining History of the Cheshire Basin – Chris Carlon 19 5.7 The Salt Deposits, Brines and Mines of Mid-Cheshire – Chris Carlon 21
1 INTRODUCTION
The 2012 conference was centred on Quarry Bank Mill at Styal, Cheshire. The venue, a cotton mill owned and run by the National Trust, provided lecture space, refreshments and meals and camping space for the weekend. The conference was run by the Derbyshire Caving Club wit considerable help from other clubs and organisations. The speakers are listed in section 2 and trip leaders in section 3.
This report contains summaries of the talks but where we have been provided with a longer paper by the speaker, these have been included. The summaries are presented in subject order rather than the sequence in which the lectures were held as there were some topics covered by more than one lecturer.
The theme of the conference was developed from the following: ‘Copper, lead, cobalt, salt, coal, fireclay, limestone – Cheshire’s mining history’. However, as speakers came forward, the geographical extent developed to cover north Staffordshire and Stockport while the subject matter included modern mining elsewhere in England and Germany. The intention was to steer away from the ‘traditional’ areas of British metal mining.
I am very grateful to all those who helped by offering and giving talks, arranging and running trips, working on reception and providing moral support before and during the conference. For the latter, I am particularly indebted to my wife, Liz Taylor and to Pete Johnson. After the conference, I tried to contact and acknowledge the help from all those involved so I will not repeat those thanks here.
Nigel Dibben Nantwich, December 2012
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2 LECTURES
The speakers involved were: • John Barnatt • Kevin Dranfield • John Prag • David Barrie • Steve Grudgings • Neil Rowley • Chris Carlon • Peter Johnson • Thomas Seers • Paul Deakin • David Kitching • Martin Straßburger • Nigel Dibben • Steve Mills • Simon Timberlake The programme as presented was as follows:
FRIDAY 2100 – 2200 Paul Deakin The Alderley Edge Mines in pictures SATURDAY 0920 – 0930 Ian Thomas (Chairman) Welcome and introduction 0930 – 1020 Chris Carlon Geology, Mineralisation and Metal Mining History of the Cheshire Basin 1040 – 1100 Professor John Prag Introduction to the AELP 1100 – 1150 Simon Timberlake Bronze Age copper mining 1150 – 1240 Nigel Dibben Alderley Edge 1857-1877 1400 – 1450 Martin Straßburger Mining archaeology of a 19th-20th century lignite deep mine at Kausche, Lower Lusatia 1400 – 1450 lower room Kevin Dransfield Underground Stockport 1510– 1600 Pete Johnson Mining techniques illustrated at Alderley over the ages 1600– 1650 John Barnatt Ecton Mines: solving the problems of mining at great depth 1600– 1650 lower room Thomas Seers Use of laser imaging in mine survey work SUNDAY 0900 – 0950 Steve Mills Alderley Edge: the DCC’s exploration 0950 - 1040 David Barrie Goodluck Mine: lead mining and barite into the 20th century 1100 – 1150 David Kitching Poynton coalfield 1150 – 1240 Paul Deakin North Staffs Coalfield 1320 – 1410 Chris Carlon The Salt deposits, Brines and Mines of mid-Cheshire 1430 – 1520 Paul Deakin Winsford Salt Mining 1520 – 1610 Neil Rowley The Boulby Potash Mine
1520– 1610 lower room Steve Grudgings Newcomen’s steam engine: 300th anniversary 1610 – 1630 Nigel Dibben Close of conference
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3 TRIPS (SURFACE AND UNDERGROUND)
The conference included a programme of mining-related trips from the Friday before through to the following Tuesday. These were organised by the following who were assisted by a number of members of their respective clubs and organisations:
• Alderley Edge mines: arranged by Ed Coghlan and Paul Stubbs • Alderley Edge surface: arranged and led by Doug Kidd • Apedale heritage centre and coal mine: arranged by Paul Deakin • Astley Green colliery: made available by Red Rose Steam Society • Chatterly Whitfield colliery: arranged and led by Roy Meldrum • Ecton copper mine: arranged and led by John Barnatt • Goodluck lead mine: arranged and led by David Barrie • Hanging Flat barite mine: arranged and led by Paul Chandler • Poynton and Pott Shrigley surface: arranged and led by David Kitching • Winsford salt mine: arranged by Paul Deakin
The trip summaries shown on the conference website are reproduced below with minimal editing.
3.1 Alderley Edge mines
Brynlow Mine
This trip started with a visit to Brynlow Mine before going down to the Hough Level. Parts of Brynlow date back to Bronze Age and the 18th century. Once in the Hough level a boat was used to ferry the delegates through the flooded section and into Engine Vein. The route ascended from the Hough Level via Blue Shaft with an opportunity to see the colourful blue staining in the shaft. The trip was classed as sporting as Brynlow can be muddy and a bit wet while the trip in the boat can also lead to wet patches on clothing.
Cobalt Mine
This mine was worked during the Napoleonic Wars when the Cobalt supply from the continent was interrupted and the price made working poorer grades of ore viable. It is small and can be wet (over wellington deep) and muddy; it has low sections that require flat out and hands and knees crawling. Access is down a shaft opposite the café which is fitted with a fixed iron ladder (15 metre) the exit is via a fixed iron ladder in the Museum (12 metre) or through a shaft at the end of the car park behind the Wizard Restaurant, both of which make an interesting through trip. Trips into the Cobalt Mine were self-guided.
Engine Vein
This trip was guided by members of the Derbyshire Caving Club. The mine is designated as a Scheduled Ancient Monument as it contains excellent examples of Bronze Age, Roman, Georgian and Victorian mining. It has also been worked for copper, lead and cobalt ores within the Triassic sandstones. The entrance is via an iron door with an incline down to the main vein, followed by a series of steps that descend to the main part of the mine. This trip allowed more time to explore the mine more fully and to descend into the Hough level.
Engine Vein SRT
The trip was guided by members of the Derbyshire Caving Club. It was only for delegates with their own SRT equipment and the competence to use it. Square Shaft (50 metres) was descended followed by a prusik part way up Bear Pit (25 metres) followed by the final pitch to surface via New Year shaft (10 metres). There were opportunities to visit the workings in Engine Vein between pitches.
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West Mine
This trip was classed as sporting and was guided by members of the Derbyshire Caving Club. There was a combination of fixed iron ladders (max 4m) and SRT. The route included a traverse line along an exposed wall, scrambles, ascents and descents of shafts for which the visitors needed full SRT equipment. The route has open cavernous chambers and interconnecting levels and encompassed the whole of the mine including some passages with knee-deep water in them. Two routes were used, one keeping to the eastern part of the mine and the other taking in the whole mine.
Wood Mine
This fuller trip of Wood Mine trip was guided by members of the Derbyshire Caving Club. There were opportunities to take photographs and explore the full extent of the mine. This trip included low sections, crawling and some fixed iron ladders (maximum 4 metres).
There were variants on some of the above trips including easier routes and routes without SRT kit being required. For more information on all Alderley Mines including the detailed location grid references, visit www.derbyscc.org.uk/alderley.
NGR SJ 859.772
3.2 Alderley Edge surface Led by Doug Kidd
Alderley Edge has a long and interesting history; as a prominent point in the Cheshire plain it was used by Neolithic man as a vantage point for hunting parties. Bronze Age man then discovered its mineral wealth; Romans, Georgians and Victorians also mined here each leaving an indelible mark on the landscape. The walk started from the museum and visited Engine Vein to see the Bronze Age workings then onto the mines around Stormy Point and Saddlebole before returning to the museum passing the Hough Level on the way. Delegates wishing to do so could visit the treatment works site and Windmill Wood.
3.3 Apedale heritage centre and coal mine Arranged by Paul Deakin
Apedale Colliery is located at North Staffordshire's, Apedale Heritage Centre. The morning visit was taken into the underground workings not normally accessible to the public as this section of the mine has to be force-ventilated beforehand. The tour was guided by experienced miners who have a wealth of information about the mine, geology and local history. The afternoon visit was taken along the underground museum route also guided by experienced miners. There was an opportunity to visit the surface features and museum.
For more information, visit www.apedale.co.uk. NGR SJ 8232.4854
On the same site are the Apedale Valley Light Railway and the Moseley Railway Trust which run industrial narrow gauge railway locomotives and rolling stock. There is a locomotive at the MRT site that was formerly used by the DCC in the Hough Level at Alderley Edge.
For more information, visit www.avlr.org.uk and www.mrt.org.uk.
The Apedale Community Country Park is on the doorstep, offering 184 hectares of open space to explore. The park offers a varied landscape of woodland, meadows and pools crossed by many paths and tracks. Overlooking the park is a memorial in the form of a pit wheel dedicated to the mine workers of Staffordshire.
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3.4 Astley Green colliery Made available by Red Rose Steam Society
The museum occupies some fifteen acres of the Astley Green Colliery. The engine house has a 3,300 hp twin tandem compound steam winding engine and headgear the museum houses many exhibits, not least of which is the collection of 28 colliery locomotives, the largest collection of its type in the United Kingdom. The colliery began its life in 1908 to exploit coal reserves in the south Lancashire Coalfield. The museum has its own unique photographic archive and is now run and maintained, on behalf of the community, by the Red Rose Steam Society Limited, a registered charity based in Lancashire.
For more information, visit www.agcm.org.uk. NGR SJ 7045.9999
3.5 Chatterley Whitfield colliery Arranged and led by Roy Meldrum
Chatterley Whitfield is acknowledged as the most complete record of colliery building in the country and, although given Scheduled status by English Heritage in 1993, its future is far from secure. A regeneration partnership set up in 1999 has achieved some success in refurbishing and bringing back into use some of the office buildings, but much of the site is in extremely poor condition. The Friends of Chatterley Whitfield have been involved with the regeneration project for 10 years, aiming to preserve this unique piece of heritage and promoting it to a wider audience. Public access is normally restricted to the annual Heritage Open days but the City Council, the site owners, sanctioned a special visit by NAMHO members. Delegates were able to see the deployment centre, the recently refurbished main offices, lamphouse and inside the rebuild of the middle pit winding house.
For further information, visit www.chatwhitfriends.org.uk. NGR SJ 8830.5532
3.6 Ecton copper mine Led by John Barnatt
The Ecton Mine is now run as an Educational Trust with the principal aim of promoting education in applied geology, mining and mineral extraction. Mining started at this site in the Bronze Age; its heyday was in the 18th century when the Duke of Devonshire made a profit of over £300,000, reputed to have financed the building of the magnificent crescent in Buxton. Total ore production is estimated at over 100,000 tonnes, mainly of copper ore. In the late 18th century, Ecton was in the forefront of developments in mining technology, and both chemistry and geology themselves developed rapidly as a result of these advances in technology. Among the achievements at that time were the sinking of the deepest mine shaft in Britain, the reputed first use of explosives in British mines, the building of an early Boulton and Watt steam engine, and the efficient use of water power for mine pumping. The whole area is a site of special scientific Interest (SSSI), and the Ecton mine itself is an underground SSSI. The rock exposures at nearby Ape's Tor provide outstanding opportunities for the study of geological structures, which can then be seen again underground in Salt's Level. Delegates were guided into the Clayton and Deep Ecton Levels by John Barnatt.
NGR SK 0966.5825
3.7 Goodluck lead mine Arranged and led by Richard Halford
Members of the Goodluck Mine Preservation Club guided delegates into this typical Derbyshire lead mine of the mid nineteenth century, which contains both original surface and underground features. Underground there are displays of tools and genuine artefacts found during exploration. There was a through trip starting from a shaft near to the top of the hill followed by a single pitch of 12 metres to a connecting passage leading to Goodluck Mine itself. There was then a descent using around 30m of fixed ladders down to the main level. Delegates then explored the remainder of the mine off the adit. An alternative trip not involving SRT was also provided.
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For more information, visit. www.goodluckmine.org.uk/index.html If you click on ‘New Trip’ off the home page there are pictures of the shaft, connecting passage and part of the ladder route.
NGR SK 2690 5650
3.8 Hanging Flat barite mine Led by Paul Chandler
After descending a short, low crawl, access was gained into a roomy entrance adit. A two-way junction was soon reached. Left, a roomy passage in country-rock led to working faces through short insets, passing vein workings. Right, again roomy, led to further workings and a blind shaft in the floor. The mine was worked for fluorspar in the late 1970s and early 1980s but the entrance collapsed in the mid-1990s. Reference: Caves of the Peak District (2010 edition).
NGR SK 2063.7601
3.9 Pott Shrigley surface Led by David Kitching
David guided delegates on a surface walk looking at the mining remains of the East Cheshire coalfields around Pott Shrigley and Lyme Handley. These mines worked up to seven thin coal seams and the associated fireclays from the 18th to mid-20th centuries century from shafts using mainly horse gins and windlasses for winding. An extensive firebrick industry developed to utilise the clay and has left many remains. The walk was around 2 miles long over moorland and rough ground.
NGR SJ 9553.7956
3.10 Poynton surface Led by David Kitching
David guided delegates on a surface walk, looking at the mining remains of in the Poynton coalfield from the 18th to 20th century. The Poynton collieries were the largest and most extensive in Cheshire. From its earliest recorded workings in 1589 and until the final closure came in August 1935 the Poynton coalfield played an important part in the industrial development of North-east Cheshire and Stockport. The walk was around 4 miles long mostly along public footpaths and roadsides.
NGR SJ 9445.8336
3.11 Winsford salt mine Arranged by Paul Deakin and led by Salt Union Limited
Salt Union Limited is one of Britain’s largest industrial salt companies. At the site in Cheshire, they manufacture and produce a comprehensive range of rock salt products. The site in Winsford is one of only two dedicated Rock Salt Mines in Britain where, 150 metres below the surface, a range of consistent quality de-Icing salts is produced. The mine is also the location of a secure storage facility and a facility to store dry waste products. A tour is rarely available to the public and NAMHO was particularly indebted to Paul for arranging this.
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4 SUMMARIES OF LECTURES
The summaries have been grouped as follows:
• Alderley Edge (and Bronze Age copper mining) • Salt and potash mining • Coal mining in Cheshire and North Staffordshire • Metal mining in Derbyshire and Staffordshire • Other subjects
Where more detailed papers are available, these have replaced the summaries. Summaries have been edited for consistency.
4.1 Alderley Edge and related topics
The Alderley Edge Mines in pictures – Paul Deakin
As an introduction to the conference, Paul’s superb photographs showed off the main features of the copper, lead and cobalt mines at Alderley Edge. The mines have been worked from the Bronze Age to the twentieth century and the Derbyshire Caving Club reopened the mines from 1970 onwards. Latterly, the mines have been resurveyed by Paul and archaeological work has been carried out on a number of sites.
Geology, Mineralisation and Metal Mining History of the Cheshire Basin – Chris Carlon
This talk presented an overview and introduction to the geology, mineralogy, distribution and history of metal mining in the Cheshire Basin from pre-history to its heyday in the mid-late 1800’s. It concentrated on the distribution of the known occurrences of barite and copper-lead-manganese- cobalt mineralisation and the mines and mining history of the Alderley Edge, Mottram St Andrew, Bickerton, Clive and Eardiston mines. It provided the background to surface and underground tours at Alderley Edge and answered the most frequently asked questions about the mineralisation and the mine workings.
A more detailed paper is provided in section 5.6.
Introduction to the AELP – Professor John Prag
Professor John Prag gave a brief introduction to the Alderley Edge Landscape Project set up by the Manchester Museum and the National Trust which ran from 1996 to 2005: its aim was to study the entire history of the Edge, from its creation in geological time to the coming of the railways and the villas. A specialist volume on The Archaeology of the Edge was published in 2005 by British Archaeological Reports and J. & E. Hedges (Oxford). A second massive volume called Living with the Edge: Alderley’s Story is in preparation. This covers the rest of the story: the geology of the Edge, its natural history, the story of the mines, the social history - the villas, the paths and tracks, the names and the stones - and of course the legend. It will be published by Manchester University Press, and should appear in late 2013.
Bronze Age copper mining – Simon Timberlake
A long-term programme of archaeological fieldwork carried out by the Early Mines Research Group has led to the dating of eleven Early Bronze Age copper mines; nine of these in Wales (which includes Parys Mountain (Anglesey) and Copa Hill (Cwmystwyth), Nantyreira, Nantyrarian, Llancynfelin, Erglodd, Ogof Wyddon and Twll y mwyn in Central Wales and two in England (at Alderley Edge in Cheshire and Ecton in Staffordshire). Together with the larger Bronze Age – Iron Age workings on the Great Orme, some 12 Bronze Age mines have now been examined. The geological environment of these mines and ore deposits was discussed briefly, along with the possible ores extracted, the strategy of prehistoric mining, tool use, and any evidence for processing or associated material culture. The radiocarbon dates from the mines indicate a relatively short phase of widespread
- 9 - Proceedings of the 2012 Annual NAMHO Conference prospection dating from the very beginning of the 2nd millennium BC, most of the sites being abandoned by the Middle Bronze Age. This paper compared recent mining archaeological work undertaken on Ecton Hill (at Stone Quarry (Dutchman) Mine and The Lumb) with that undertaken on Alderley Edge as part of the Alderley Edge Landscape Project in 1997-8.
Alderley Edge 1857-1877 – Nigel Dibben
When mining restarted at Alderley Edge in 1858-9, the proprietor was James Michell who had worked in Spain, Derbyshire and Bristol before coming to Alderley. His specialism was in smelting and recovery of metal from slag so he saw the opportunity to recover copper from the sandstone at Alderley Edge. He was assisted by a very able young chemist, William Henderson, who went on to run the Tharsis mines in Spain. The talk described the era and the association between the mining industry at Alderley Edge and the chemical industry in Northwich.
A more detailed paper is provided in section 5.3.
Mining techniques illustrated at Alderley over the ages – Pete Johnson
One of the features of the mines at Alderley Edge is the long history which can be seen in situ in every phase. The history is still visible in the form of Bronze Age pit workings, a Roman shaft and level, 17th and 18th century coffin levels, 19th century blackpowder blasted stopes of considerable size and 20th century tunnels shaped by dynamite. The talk explored and illustrated the evidence underground for all these phases of working.
A more detailed paper is provided in section 5.4.
Alderley Edge: the DCC’s exploration of Mottram St Andrew Mine – Steve Mills
The talk illustrated the work that has been carried out at Alderley Edge over the last thirty five years with a focus on the mine at Kirkleyditch. The Mottram mines are currently inaccessible so the talk gave a rare insight into a mine where vanadium minerals were found.
4.2 Salt and potash mining
The Salt deposits, Brines and Mines of mid-Cheshire – Chris Carlon
The Triassic rock salt deposits in Mid-Cheshire are the basis of a long, dynamic and colourful history. The talk looked at the geology of the deposits, salt production from brine springs, the discovery of the 'Top Rock' at Marbury in 1670, and the mines which subsequently exploited the rock salt deposits around Northwich. It also recounted and illustrated the natural subsidence and man-made spectacular ground collapses which resulted from uncontrolled brine pumping, and looked at modern salt production by solution mining at Holford-Byley and rock salt mining at Meadowbank Winsford.
A more detailed paper is provided in section 5.7.
Winsford Salt Mining – Paul Deakin
The Winsford Salt Mine, also known as Meadowbank, provides much of the rock salt used in England and Wales. It also provides space for the deposit of archives and waste. Paul has been a regular visitor to the mine and his daughter currently works there as a surveyor. The talk illustrated the current methods of working in this vast underground space and provided information to complement the mine visit.
The Boulby Potash Mine – Neil Rowley
Boulby is many miles from Alderley Edge and Cheshire but has similarities in the geological formation and the relative unusualness of the mineral worked and location. The mine is surrounded by iron mines that fed the Teesside steel industry but Boulby works potash and common salt in beds far below the iron beds. It will soon be commencing to mine Polyhalite from a seam below the current workings. - 10 - Proceedings of the 2012 Annual NAMHO Conference
The talk also referred to the proposed development by another company of the Polyhalite reserves South of Whitby.
4.3 Coal mining in Cheshire and North Staffordshire
Poynton coalfield – David Kitching
Coal mining in Cheshire was never on the scale of neighbouring counties, but the Poynton coalfield was developed with deep mines that worked until 1935. The history of the workings and the struggle to transport the coal to the industrial markets of Stockport and south Manchester was illustrated along with the early and extensive use of steam power and the remaining structures and archaeology.
A more detailed paper is provided in section 5.1.
North Staffs Coalfield – Paul Deakin
Paul provided a description of the mining in North Staffordshire coalfield illustrated by his own underground photographs. He has the benefit of long experience as a mine manager as well as surveyor and photographer. The talk showed the recent history of the coalfield and included some coverage of Chatterley Whitfield and Apedale, both sites which could be visited over the weekend.
4.4 Metal mining in Derbyshire and Staffordshire
Goodluck Mine: lead mining and barite into the 20th century – David Barrie
Goodluck Mine is a unique survival of a typical Derbyshire lead mine of the mid nineteenth century, with both original surface and underground features. The talk covered the history up to the recent past and linked with visits to the mine before and after the conference.
A more detailed paper is provided in section 5.5.
Ecton Mines: solving the problems of mining at great depth – John Barnatt
In the later-18th century the Ecton Mines in the Staffordshire part of the Peak District were some of the deepest mines in Britain. Between 1760 and 1890 a series of engines were used to bring out ore from up to 1000 feet below river level, and to power pumps to keep the mines dry. A detailed archaeological survey has thrown much new light on how the main engine chambers deep within the heart of the hill were used.
4.5 Other subjects
Mining archaeology of a 19th-20th century lignite deep mine at Kausche, Lower Lusatia – Martin Straßburger (see section )
Since the beginning of 2011, an old lignite deep mine has been excavated by the open cast mine of Welzow-South in the southeast of the federal state of Brandenburg (southern Lower Lusatia). This talk mostly concerned the mine „Mariannensglück“ at Kausche which was worked from 1895-1937. The talk was about the conception for recording these old mines parallel to the current mining operations and the archaeological work carried out so far.
A more detailed paper is provided in section 5.2.
Underground Stockport – Kevin Dransfield
The tunnels and waterways below Stockport feed the cotton mills that were developed in the Mersey valley in the 1700s. The network still exists although it has been taken over for other uses including carrying electricity cables. The talk showed historic and present evidence for the waterways under Stockport. A model of one of the mills was also on display.
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Use of laser imaging in mine survey work – Thomas Seers
Terrestrial laser scanning produces highly accurate three dimensional images of real world scenes, with surveys typically generating tens to hundreds of millions of x, y z points resolved with positional accuracies of less than one centimetre. The true-colour 3D models produced using laser scanning combined with digital imagery are opening up new frontiers to geologists, with difficult-to-access rock exposures, such as those found within mine workings, being subjected to more exhaustive investigation than has been feasible hitherto. This presentation detailed work currently being carried out within the School of Earth, Atmospheric and Environmental Sciences at the University of Manchester, where laser scanning derived models of rock exposures from the mines of Alderley Edge are being used to enhance our understanding of the Triassic aged sedimentary rocks through which the workings are cut. A live demonstration of datasets obtained from the West Mine and the Engine Vein Mine was provided. The presentation allowed plenty of time for hands-on demonstration and discussion.
Newcomen’s steam engine: 300th anniversary – Steve Grudgings
The numbers of early Newcomen Engines installed in the Bristol Coalfield was only surpassed by installations in Tyneside, West Yorkshire, Shropshire and Cornwall. For one of these engines installed at Coalpit Heath, Gloucestershire in 1751, a complete set of suppliers’ bills exists and Steve's talk examined these bills as a basis for understanding how these early engines were built and the skills required to do this.
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5 PAPERS
This section contains more detailed papers where it has been possible for the speakers to provide them.
5.1 Poynton Collieries, a brief history – David Kitching Whilst Cheshire is not known for coal mining the county benefits from lying over the outlying parts of three coalfields. Along the Dee estuary the North Wales coalfield was worked around Denhall and Parkgate whilst the North Staffordshire seams were worked at Mow Cop and near Kidsgrove. The most productive area was in North East Cheshire where the lower seams of the Lancashire coalfield are to be found to the East of the Red Rock Fault as it runs down towards Macclesfield.
Poynton lies a few miles to the south of Stockport and it is here that the most productive of the Cheshire collieries were to be found. Thirteen workable coal seams varying in thickness from 2 ft to 6 ft are found in the area and several of these outcrop towards the eastern edge of the parish. The coal field is bounded to the west by the Red Rock Fault which runs north to south a little to the east of the Hazel Grove to Macclesfield road (A523).
Shallow mining and outcrop working of the seams is recorded from 1589 and by 1635 the coal was being worked at depths of 50-60 ft and water problems were being encountered where soughs could not be constructed to drain the workings. The Poynton pits were worked along with those in the adjacent Norbury parish and the Norbury Brook was used to provide power for waterwheel driven pumps from at least 1700. Development was steady throughout the eighteenth and early nineteenth centuries with steam pumping engines being installed before 1764. By 1826 some 18 pits were being worked by the colliery tenant William Clayton. There were 3 beam pumping engines, 9 steam winding engines, 5 horse gins and two windlasses in use.
With the opening of the Macclesfield Canal the markets of Macclesfield and Bollington to the south and the towns to the north and east of Manchester became accessible and output rose from 86,514 tons in 1831 to 180,184 tons in 1836-7 with profits of £30,049. Control of the collieries reverted to Lord Vernon the landowner and the Vernon family retained sole control until the formation of Poynton Collieries Ltd in 1921.
The building of the Macclesfield branch of the Manchester and Birmingham Railway in 1844-5 saw the section from Cheadle Hulme to Poynton collieries opened to traffic on the 9th June 1845. Railway transport opened up further markets to Poynton coal, particularly Stockport and stations to Crewe and output rose again to reach 237,000 tons in 1846.
By the mid nineteenth century the focus of the collieries had moved from the outcrop of the seams to the deeper coals lying in the west of the coalfield towards the Red Rock Fault. Output became concentrated at the Park Pits which were sunk in 1844-5, Lady Pit which was sunk in 1835 and the Anson Pit which was already working in 1826. In 1862 Lord Vernon employed G. C. Greenwell, a highly respected mining engineer who had previously been manager of the Radstock Collieries for Lady Waldegrave, as colliery engineer and agent. Greenwell was succeeded by his son G. C. Greenwell in 1877, and grandson G. H. Greenwell who took over in 1919 and remained in control of the colliery operations until closure in 1935.
The last new sinking at Poynton was the Lawrance Pit which was intended to win the Accommodation seam over a wide area up to the Red Rock Fault. Several of the other seams were becoming worked out and production was becoming difficult to maintain at profitable levels. In 1897 output at Poynton was 244,516 tons or about one third of the county total.
In the twentieth century the pumping of water from the workings was becoming a significant burden on the collieries. In the late eighteenth and early nineteenth centuries the Poynton and Norbury collieries had been worked as one unit by the lessees and had been connected underground. The last Norbury pit closed in 1892 whilst the Adlington collieries to the south had closed in 1878. Water from all these workings was finding its way into Poynton and increasing pumping costs. In 1926 Poynton Collieries Ltd undertook a scheme to electrify the pumping and ancillary operations in order to reduce costs.
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The scheme was carried out by the British Thomson-Houston Co. Ltd of Rugby under the direction of Ravenshaw and Dyer, consulting engineers.
The coal seams were approaching exhaustion and closure became inevitable. Anson Pit had closed in 1926 before the electrification scheme and Park Oval Pit followed in 1928. The Lawrance Pit continued to produce 70,000-80,000 tons per year until the 30th August 1935 when the long and productive history of coal production at Poynton ended.
5.2 Mining archaeology of a 19th-20th century lignite deep mine at Kausche, Lower Lusatia – Martin Straßburger Today, Germany is the country with the largest lignite production worldwide. For the history of the mining industry and the industrialization in this country, lignite mining is quite essential. Lusatia is one of the most important producers. Since the 1880s it is a key factor in the social and economic development of Lower Lusatia, which since 1956 reached dimensions unknown up to then. It was of special importance for the textile industry with its centres in Cottbus, Forst, Guben, Finsterwalde, Peitz and Sorau. The interactive influence of industry and mining can be frequently observed.
Fig. 1 – Bucket wheel excavator in the open cast Welzow-South with collapsed workings in the background (M. Straßburger)
Old mining relics are a valuable archaeo- logical resource, which should be recorded when and wherever possible. Since the beginning of 2011 old lignite deep mining has been excavated by the open cast mine Welzow-South in the south east of the federal state of Brandenburg (cf. fig. 1 and fig 2). This mostly concerns the mine „Mariannensglück“ at the former village of Kausche which was worked from 1895- 1937.
The first step which assisted in identifying historical mining methods at this mine was a desk-based assessment. The operating plans designed for the mine for a year had also to be considered. Apart from the textual description of the past operations they contain plans for further development. Situation, ventilation and other plans as well as detailed drawings of technical installations were included in the operating plans for the mine. The surface workings are subjects for several separate specialist studies, especially for the briquetting plants and the railways. These studies make possible a detailed reconstruction of the development of the operations over time. Preliminary work on history, analysis and re-orientation of the plans as well as the drilling in the course of supporting and plugging also proved relevant for mining archaeology.
Recording in the operational open cast mine required understanding of the current technologies employed and the operating procedures. The most important con- clusions drawn from research, analysis and meetings were incorporated in a research plan.
Fig. 2 – Sections through collapsed workings in the open cast wall (M. Straßburger).
The general conditions for working in the open cast Welzow-South are important for mining archaeological recording as all activities have to conform to them. Apart from the general extraction plan the special operating schedule for traversing and retreat working as well as safety regulations in the open - 14 - Proceedings of the 2012 Annual NAMHO Conference cast are essential. There has to be complete agreement with the management of the open cast. Schedules for the year, months, weeks and days are not to be affected.
Modern lignite deep mining at Kausche or around Welzow is a research object with special potential, particularly for archaeology which has a different content and value of cultural evidence as for older periods. The examination of historically well-documented mines from an archaeological point of view can result in an important contribution for understanding. Thereby processing partly shows different details which complement the historical tradition. Even the voluminous material from the 19th and 20th century has gaps as only those aspects of mining are dealt with the management was concerned with. Everything else was assumed as known and taken for granted. But archaeology does far more than only filling gaps in the historical tradition. It often creates new perspectives which lead to a questioning of the documents' content and have to hold against the traditional mining historical understanding. An intensive and continuous cooperation of archaeologists, historians, engineers and geologists could make possible the formulation of further overriding questions, e.g. within the scope of a micro study for the area around Welzow.
5.3 Alderley Edge 1857-1877 – Nigel Dibben The mining history at Alderley Edge spans 3 millennia but the most productive period was between 1857 and 1877 under the management, initially, of James Michell. During this time, the mines also received more attention by geologists and archaeologists than at any time before so there is better information available about the main players. Sadly, the only thing lacking (at present) is any photographic record during the working period. One of the visitors at that time remarked:
“The sandstone copper mines at Alderley Edge … will amply repay a visit as regards the interest attached by the novelty of such works in this country or by the magnitude and importance of the promised results. … The Alderley [mine] has been at work for some years, under the able management of the much regarded Mr. Michell.” (1863, G Henwood) and this sentiment remains true up to the present.
Before 1857, several mines had been worked at Alderley Edge. Most were worked independently although under one management at a time, including Charles Roe in the 18th century. The extent of mines worked before 1857 is very small. The late 19th century development started in 1859 with the formation of a limited company, a novelty at that time, with directors interested in mining and with experience of ore processing. The company used techniques modern for their time to develop the mines as a single entity increasing efficiency and reducing ore handling costs. Over the 20-year life of the mine, they processed around 200,000 tons of ore to get 3500 tons of copper. The main characters involved were James Michell and William Henderson.
James Michell was a Cornishman born in 1796 who developed skills in ore processing setting up a factory in southern Spain with the so-called Spanish hearth in 1843. By the 1850s, he was back in Britain and ran a lead smelter at Stonedge, near Chesterfield and then moved to Bristol to reprocess copper-rich slags at Crew’s Hole. That business failed and he became bankrupt but recovered by 1857 when he started to investigate Alderley Edge. Sadly, he died in a fall in one of the mines in 1862. After another two or three years, the company changed managers and was run by a local consortium.
Fig. 1 – Notice of Michell’s death in the Bristol Gazette for 4th December 1862.
William Henderson was the main provider of the technical input. He was born in 1827 in Scotland making him some 30 years the junior of Michell. He patented processes subsequently used at Alderley Edge. His career started in London where he married in 1850 and where he called himself a smelter and refiner but he moved to Bristol where he met or worked with Michell. He followed Michell to Alderley Edge where he lived and raised part of his family. Next, he established businesses in Spain, Scotland and
- 15 - Proceedings of the 2012 Annual NAMHO Conference the copper works (Tharsis Sulphur and Copper Company) at Widnes. He died on the way back from Spain in 1880. His major contribution to the knowledge of the mines that we know have was the writing of three letters to the Mining Journal in 1860 describing the mines and processing plant in some detail.
Fig. 2 – Diagram of the Henderson Wet Process as carried out at Alderley Edge.
It is worth mentioning a couple of the miners and managers at Alderley who had similarly interesting backgrounds. For ex- ample, Stephen Osborne, born 1831 at St Hilary, Cornwall, was the son of a copper miner and then became a copper mines carpenter at St Hilary in 1851. He married Arabella and became agent of iron mines in Isle of Man before becoming Alderley mine captain around 1865. Later, he emigrated to Australia (Adelaide) and when he died in November 1912, he was well-enough known to rate a mention in the Australian papers.
Another person involved, but not directly with the mining, was Jonathan Down, born in Calstock in 1835. He was listed in the census as a lead smelter in Derbyshire in 1851. He married Mary at St Georges, Bristol, just down the road from Crew’s Hole. He then became mine agent for AEMC in 1861, presumably following Michell to the new venture, and later became agent at copper works in Widnes which were almost certainly set up by Henderson.
Some of the ‘blue-collar’ workers show similar backgrounds such as Tom Cooper who was born in Calow, Derbyshire in 1835. He became an engine driver living at Chesterfield, also married a Crew’s Hole lady and then became Engine Feeder at Alderley and subsequently Engine Driver at the copper works in Widnes. John Hooper was born about 1835 in Calstock and married Isabella, also from Calstock. But his first two children were born in Chorley (Alderley Edge), Cheshire and his third at Clive, Shropshire. His fourth child was born at Adderley in Shropshire 1867. He died young at less than 37 years old.
William Henderson, the company chemist in the early 1860s developed and patented the so-called wet process for extraction of copper from ores and slags. The concept had been known since time immemorial and had been used for assaying but recent developments in industrial chemistry meant acid was available and the process became financially viable. Of particular interest at Alderley Edge was the availability of hydrochloric acid as a waste product from the Leblanc process in use in Northwich and Widnes at that time. Henderson saw this as a replacement for the sulphuric acid which was a by-product from his Spanish ventures later. The process involved digesting the malachite contained in the pores of the sandstone with a strong acid solution producing copper chloride liquor. This was transferred to tanks containing scrap iron and through the process of ion-exchange, copper was precipitated and the iron went into solution as iron chloride. The result was a highly efficient process making copper about 80% pure, even if the overall quantity was low. As a result, the company was financially strong and paid dividends every year of its life.
During the 1860s, the plant also produced copper sulphate as a wood preservative and this was repeated in later working in the early 20th century.
In conclusion, the period from 1857 to 1877 provides an interesting insight into the development of the chemical industry, modernisation of mining and the mobility of miners and other workers. More detail about the mines and the people concerned can be found on the DCC website at www.derbyscc.org.uk.
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5.4 Mining techniques through the ages at Alderley Edge – Pete Johnson
Early pit workings were first identified as possible Bronze Age workings by Roeder and Graves in 1901. They identified more than five pits but obviously had no way of proving their assumptions. Amongst the finds were large numbers of discarded stone hammers with grooves pecked into them for attaching a wooden hafting. In 1995, members of the Derbyshire Caving Club capped a shaft by Engine Vein close to a footpath that involved digging out the top two metres of the shaft fill. In the course of this work, they came across a hoard of 564 bronze coins in a broken clay pot; these coins were mostly 3rd century Roman. This sparked off a 2-year multi disciplinary project, which started in 1997 to record the historical features of the Edge with John Prag as project leader and Simon Timberlake as the Surveyor and project consultant.
While excavating trenches at the side of the open cast Simon also found undisturbed pit workings that displayed evidence of fire setting and contained broken stone hammer fragments and some charcoal, this was dated to 1760–1955 BC. While these working have been extensively studied and documented, the chronology of the rest of the workings has not received the same attention.
Very little documentary evidence exists relating to the individual mines at Alderley. The purpose of the study presented in this talk and summary paper is to establish a chronology that can be used to identify workings of similar periods at the Edge by collating data from observations and measurements. The study is still in progress but two examples from the findings are shown here.
Triangular shot holes
The example above shows how the blast is concentrated into the corners where the fractures form and radiates out at an angle of 120 degrees. The miners at Alderley became proficient at exploiting this method and aligned the shot hole to help propagate a weakness, joining existing fractures, or directing the force of the blast. The direction of the shot holes gives valuable insight to the development of the workings; in the case of Wood Mine, we can see that the mine evolved from the expansion of five surface shafts.
Fig. 1 – A triangular hand-drilled shothole in Wood Mine
Fig. 2 – Forefield in a hand picked passage.
Hand picked levels
A level with abandoned work in progress gives a visual example of the techniques used. This enables us to marvel at the workmanship involved and the distances over which such levels were driven at times.
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Comparative observations show that while general methods were adopted, individual techniques are evident; this study is ongoing. It is hoped that a constructive chronology can be built up to help allocate a time period to workings that can be transposed to associated workings at the Edge.
5.5 Goodluck Mine, Derbyshire – David Barrie The mine is located on the Via Gellia in Derbyshire, close to Middleton by Wirksworth – not far from Cromford. The site is important with intact coe, powder house and spoil heap, giving an excellent idea of a small working mine of the period. The underground workings are also accessible to members of the general public – giving them a view of wonderful stone stempling and inscriptions dating back to 1831. The adit that we know and use now was driven in 1830, reaching the vein in 1831 and also intersecting older shafts. But we know that the history of the mine starts long before then – the only reference being in 1783 when Gemelial Hall fell down a ‘turn’ and died.
The mine was rediscovered and public access restored in 1972 thanks to the efforts of Ron Amner, Peter Naylor, John Wilmott and many other members of caving clubs (such as the Rolls Royce Club and Peak District mines Historical Society) after records discovered by Jim Rieuwerts indicated the size and importance of the mine. The entrance that was blown in during the 1950s was finally re- opened. Among the work that was carried out then was the installation of an escape route to satisfy the mines inspector and a massive amount of passage clearing. There was excitement too – with sweating explosives and detonators needing to be removed.
The next phase began in 2006 – Ron Amner who was the last custodian of the mine wanted to pursue other interests and there was a real risk that the mine would have had to be abandoned. Peak District Mines Historical Society did not want to take on responsibility. Following meetings in 2006 a new Club was formed under the chairmanship of Peter Naylor. Members brought a range of special talents and abilities to the group, from practical mining experience, to health and safety expertise. By July 2007 the Bar Mote court had awarded us ownership again. One of the early members to join was one Brian Spencer – distant relative of the GS or George Spencer who had marked his name in the mine back in 1831. Another member to join was one Simon Alsop – a distant descendent of the original mine owner.
Fig. 1 – The entrance with the miners’ coe on the left of the tracks.
Early works included the clearing of the site of some materials that were no longer needed, and some maintenance. The long term survival of the mine was regarded as essential and fundraising began in earnest – work was urgently needed to replace the entrance gate. We also had to take out the necessary insurance. A website was set up and we had mugs made up, and designed a new guide to the mine – all to bring in income. We were lucky enough to receive a grant from Peak District Mines Historical Society and from the Toyota Charitable Trust. The latter gave us the money to buy new lamps for our visitors and provide some advertising material. Since then we have erected new visitor signs – which have helped attract visitors from the surprisingly large number of people who simply walk past the site. The club is now on a firm financial footing, although we are always grateful for donations!
With a committed membership of around twenty-five, most of whom are active on a regular basis, we have been able to re-explore the mine. The first big development was when we were re-exploring off the 60 ft level, off the exit shaft. Our Chairman decided to remove spoil from what appeared to be a dead end passage – fortunately there was a blind stope available for us to tip the debris down and work began apace. Another member – John Kitchener – had decided to explore shafts on the surface. This led us to re-open one shaft in a line running along the top of the hill, and descend to find a passage at roughly the same level as that off the 60 ft level. We got to the end, but it appeared to be a forefield. The trail there went cold… The dig continued and finally one Sunday a hole appeared, with blackness beyond. A wriggle through left the secretary in a large opening – and yes we had a connection! What is interesting is that from the other side the connection had been carefully - 18 - Proceedings of the 2012 Annual NAMHO Conference disguised… an early attempt to fool the bar master? Work has been continuing since to push a passage leading off towards Black Rake, which is draughting promisingly. We’ve also had to fix a new secure lid to the shaft – now called JK mine!
We’ve re-started a dig on an internal shaft – that had been abandoned, and more promisingly two digs on a natural fault. One, having cleared miner’s debris, brought us to an old buddling area, with ample evidence of tailings. The other is on an industrial scale, and our principal diggers John Wilmott and Paz Vale have gone down around fifteen feet already – getting close to a natural rift with flowing water. The whole area here has enormous potential as it drains a large area of the hill, and promises much. Another great find came after we explored an internal shaft that had previously led to a pool of water. Up on one wall there were a series of mud tallies with the fingerprints of the old miners still evident. This alone was a remarkable survival. A new survey carried out by Peter Clook (our mine manager) has identified new prospects for digs, as well as helped us record more recent finds.
Fig. 2 – Mud tallies.
There’s much else to do – maintenance still has to be done. We have repaired cracked stemples with roof bolts, and fitted a new lid to the escape shaft. The biggest single project on this heading is the replacement of all the fixed ladders to this escape route. We’ve bought all the new ladders, and work is progressing. And when we have finished all that – there is a large shaft mound that we need to look at….
Anyone is welcome to visit the mine on the 1st Sunday of each month, and have a trip to see what we are doing. We promise that there will always be something new to see. And if you can’t make it there is a DVD out now – filmed by David Webb – that gives you an excellent history of the mine and footage of what we have achieved so far. It’s highly recommended.
Visit our website www.goodluckmine.org
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5.6 Geology, Mineralisation and Metal Mining History of the Cheshire Basin – Chris Carlon Cheshire is an area little known for metal mines but it has produced metals from pre-history to its heyday in the mid-late 1800s, from a rather unusual copper-cobalt-nickel sulphide - sulph-arsenide mineralisation which, at Alderley Edge, is accompanied by significant quantities of lead sulphide.
Mineralisation is located within Triassic (255-205 million year old) sediments which accumulated in a largely continental basin covering an area of around 3,500 km2.
The predominantly Triassic sediments comprise a lower sequence up to 1860 m thick of sandy and pebbly sediments forming the Sherwood Sandstone Group overlain by over 1500 m of fine mud rocks, silts and salt layers of the Mercia Mudstone Group.
Major and minor faults cut and displace these sediments, and have focussed and channelled the passage of hydrocarbon gaseous compounds and saline warm water containing dissolved metallic compounds. These passed into structural ‘traps’ where Sherwood Sandstone Group sediments were faulted against and/or under an impermeable seal or ‘caprock’ of Mercia Mudstone Group sediments where the metals were deposited along the faults and in the enclosing sandy and pebbly sediments.
There is a regional ‘seal’ around the basin at the junction of the two main rock groups, and it is at this position in and around discrete fault-rock traps that mineralisation occurs. This is defined by a wide - 19 - Proceedings of the 2012 Annual NAMHO Conference distribution of barite (barium sulphate) often accompanied by black, sooty manganese ‘wad’ and bleaching of the normally red, iron oxide cemented sandstone host rocks. Within this ‘envelope’ of veinlets and disseminated, often discrete, bladed crystals of barite, is a much more confined and localised metallic mineralisation.
Fig. 1 – Disseminated malachite copper mineralisation, Wood Mine, Alderley Edge.
The initially deposited or ‘primary’, hydrothermal, copper-iron, nickel- cobalt-iron, copper-arsenic, copper- antimony and lead sulphides infill the pore-spaces between sand grains within the host sandstones and conglomerates. Subsequently, these deposits, localised along and adjacent to certain faults, were uplifted, subjected to solution and re-deposition several times by near surface, circulating, acidic, ground water as the water table fell. The primary sulphides and sulph-arsenides are therefore accompanied by a bewildering array of secondary copper sulphides, and oxides, hydroxides, arsenates, vanadates, phosphates, carbonates and sulphates containing principally Cu-As-Ni-Co-Mn, and with Pb at Alderley Edge
At nine principal sites around the Basin this mineralisation has been exploited on a generally small scale along mineralised faults and spatially associated porous aquifer sandstones, sandwiched between impermeable, unmineralised mud-layers. The deposits are therefore generally ‘strata-bound’ and display cross-cutting, mineralisated, Eh-pH, oxidation-reduction boundaries or ‘redox-fronts’ of both primary and secondary type.
The largest known deposits occur at Alderley Edge and Mottram St. Andrew in the NE of the Basin and were worked periodically for copper, lead, cobalt and by-product silver. There are remains and evidence of Neolithic, Roman and Medieval mining, with extensive underground development in the 17th, 18th and 19th centuries. Mineralisation is focussed along, and associated with, a series of WNW-ESE faults over an area of about 2 km2. Exploitation has taken place over a period of 3000 years and produced superimposed workings totalling around 15 km in seven main areas over the crest and SW flanks of the Edge to a maximum depth of around 100m. In the broadest sense lead-barite rich material is located along faults, with remnant copper sulphides, while wider dispersed copper carbonate and copper silicate mineralisation is dispersed through sandy and pebbly sediments. The area is now largely protected as National Trust Property and SSSIs. Grades vary considerably but between 1857-1878 mean Cu grade ran at 1.49% and the ore was treated by a novel acid solvent extraction and chemical winning process suitable for low grade copper oxide ores. During this period around 215,000 tons of ore were treated to produced 3200 tons of copper metal.
Fig. 2 – Mine Bank, Bickerton Mine with engine shaft.
A barite-Cu-As-Co-Ni-Ag mineralis- ation also occurs at Gallantry Bank, Bickerton, in the western part of the Basin along the line of the Bickerton Fault in the red sandstone hills of the Mid-Cheshire Ridge. Grades up to 19% Cu and 25 oz/t Ag were recorded historically, mainly for promotional material as the overall grades were much less. Ore was worked intermittently between 1690-1920 from a vein-like - 20 - Proceedings of the 2012 Annual NAMHO Conference structure along the fault, up to 650 m long, 1.5 m wide and to a maximum depth of 46 m. Ore was accessed by five shafts and an adit, but none of these are now accessible. The site is marked by a red sandstone chimney stack from the 1856-1860 Engine House. Documentary materials for the mine were re-discovered in Egerton of Oulton papers in 1980 including original instructions from a German mining engineer, J.D. Brandshagen, dated 1697. The mines were promoted by the then owner, Sir Philip de Malpas Grey Egerton, a very keen amateur geologist, and the main period of activity after the late 1600’s was between 1854-1860, but the deposit was small, erratic in shape, variable in grade and generally sub-economic.
Other mines were developed on similar mineralisation in the Triassic rocks around Hawkstone Park, Wixhill, Pim Hill and Yorton in North Shropshire, but the largest were located at Clive and Eardiston.
The Clive mine was tested along the Clive Fault for a distance of 580 m and to a depth of 56 m and was comparable in size to Bickerton. The upper level and stopes (0 to 25 m depth) were connected to a lower tramming level at 55 m and mining excavated a malachite-azurite-chrysocolla copper ore with asbolite-heterogenite cobalt-manganese ‘pepper and salt’ rock. The natural movement of large quantities of water through the rocks has created a spectacular banded iron oxide feature within the host rocks. The mine was initially worked as a series of bell-pits then up to 24 small shafts. The main period of working dates from the 1860’s, but the mine was never really very prosperous.
The Eardiston or Rednall Mine near the SW border of the Cheshire Basin had a rather longer working history mainly between 1827 and 1865. Again the same copper-manganese mineralisation was encountered, with up to 25% Cu although the mean grade was around 2-4%. A fault and adjacent host rocks created a mineable zone averaging 0.62 m which was worked to a depth of 32 m and traced for around 300 m but the mine was reportedly very wet.
Early operations relied upon smelting the mixed and often complex mined ore, but the main period of mining revival in the mid-late 1800’s was very much dependent upon the innovative acid leaching technique employed. This was most successful at the largest known deposit at Alderley Edge where the Alderley Edge Mining Company Limited operated the largest mines and processing plant in the Cheshire Basin.
In all cases the mines proved to be low grade and of limited tonnage potential. Most of them were found to ‘bottom-out’ at no great depth, and were typically highly speculative, short-lived operations, involving the local land owners, experienced miners, speculators and prospectors, consultants, adventurers, chemists and risk takers. Typical mines in fact!
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5.7 The Salt Deposits, Brines and Mines of Mid-Cheshire – Chris Carlon
The Triassic rock salt deposits in Mid-Cheshire are the basis of a long, dynamic and colourful history owing to the importance of salt to mankind; its multitudinous uses; its geological occurrence in thick and extensive chemical precipitate ‘evaporite’ beds and not least to its ability to dissolve in contact with fresh water, often with serious mining and extraction implications.
Common salt, sodium chloride, the mineral halite, is an industrial mineral important as a source of rock salt, white salt and brine. It is the basis of the sodium and chlorine chemical industries; an important constituent in glass and soap manufacture; a source of salt for winter road clearing; a food additive and a chemical for hard water control. It is so common, that as Mark Kurlansky pointed out in his book Salt - A History we have forgotten that ‘… until about 100 years ago salt was one of the most sought after commodities in human history’.
Around 200 million tonnes of salt are now produced globally each year from around 100 countries to be used in over 14,000 different products.
The main source of salt is the evaporation of modern seawater in coastal ‘salars’. Cheshire on the other hand has arguably a cleaner salt, evaporated and deposited naturally from seawater over 210 million years ago and laid down in layers of rock salt.
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The occurrence of rock salt in NW England proved instrumental in the development of the ammonia- soda process by Ludwig Mond and John Brunner who set up Brunner-Mond, subsequently Imperial Chemical Industries (ICI) in Northwich in 1873. But the occurrence of salt in mid-Cheshire had been known before the Roman occupation, with brine springs being tapped and salt produced by boiling it in open pans.
No one was really concerned about the source of the brine so long as it kept flowing. It was not until November 1670 that the source of the salt was discovered at Marbury near Northwich by prospectors looking for coal to fire the brine salt-pans. They found rock salt at a depth of about 30 m and mining then rapidly took over as the main means of obtaining salt.
The salt beds occur within the Mercia Mudstone Group, a 1540 m thick sequence of red-brown mudstones, shales and siltstones in which multiple layers of rock salt occur. Two main sequences of rock salt are known: a lower one the Northwich Halite Formation and an upper one the Wilkesley Halite Formation. The Northwich Halite is historically the most important salt and brine producer, with salt bearing rocks underlying the area around Northwich, Winsford and Middlewich, the principal areas of mining and brine production.
The salt beds ‘subcrop’ below glacial sands, clays and gravel and surface water constantly dissolves the salt to produce ‘wild-brine streams’ at the ‘wet-rock head’. The salt dips below younger Triassic mudrocks where they remain dry below the ‘dry rock head’.
The brine in the Northwich area was considered the best in Cheshire, containing 25 weight % dissolved NaCl, taking 12 cwts of coal to produce 1 ton of salt. A gallon of brine could produce 2.20 to 3.00 lbs of salt. The wild brine was coming from the wet-rock head around Northwich, and the initial rock salt discovery proved to be part of a bed of rock salt up to 28 m thick, into which around 61 mines were subsequently sunk and operated between 1670 and 1781. Mining tended to excavate the lower 9m of this salt layer at depths up to 66 m, employing an internal shaft system so that surface fresh water could not penetrate into the mine and dissolve the salt.
About 2 million tonnes of salt were excavated from an area of about 12 ha (30 acres), but in 1781 an exploratory shaft was sunk through the mudstones underlying the salt bed at Marston Hall Mine and at a depth of 9 m a new and purer salt bed averaging 27 m in thickness was discovered. The originally mined salt layer became known as the Top Rock, and the newly discovered layer the Bottom Rock, separate by the 30 Foot Marl.
The Bottom Rock was then continuously mined in the Northwich area for the next 147 years between 1781 and 1928. A total of 29 mines were sunk into it and mining covered an area of 3 km2, excavating the salt layer by a room and pillar method. However, the abandoned Top Rock mines collapsed as fresh water seeped into them and they slowly filled with brine.
Fig. 1 – Platt Hill Mine collapse (from Calvert 1915).
In the mid 1800s this became an important new source of brine but pumping of the old mines led to further fresh water ingress and the start of more rapid subsidence and subsequently catastrophic ground collapses in and around Northwich. An Act of Parliament finally led to the setting up of a Brine Subsidence Compensation Board to assist the many people severely affected by the ground collapses.
The knock-on effect of extensive mining and slow ground subsidence, ground dissolution and mine brine pumping eventually led to the collapse of 18 of the 29 Bottom Rock mines, together with their associated open-pan evaporitic salt works. The area immediately north of Northwich town centre
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The last salt mine in the Northwich area, the Adelaide at Marston, finally flooded on Monday 12th March 1928 bringing mining to a close.
Fig. 2 – Winsford salt mine (Courtesy of Salt Union Ltd).
However, mining subsequently transferred to the Meadowbank Mine at Winsford in 1928, and this mine still produces rock salt from the Bottom Rock halite bed. The mine covers an area of around 15 km2 with 220 km of tunnels throughout the extensive room and pillar mine area from which up to 2M tonnes of rock salt are produced annually, principally for road gritting in winter.
Salt production in the Northwich area still continues with controlled brine pumping and cavity excavation in the Holford-Byley area. Since the 1980s the old brine caverns, excavated in the salt beds at a depth of 450-750 m below surface, have been used for industrial waste storage. The latest and important use has been the creation of the Stublach and Byley gas storage fields. Salt caverns have been excavated to produce brine but their principal use is to store over 500 million m3 of natural gas to feed and balance the UK’s natural gas transmission system.
In the same way, the caverns of the Winsford Salt mine are finding a new use as a Deep Store for solid waste disposal and also for temperature controlled and stable document storage. The old workings of the Baron’s Quay and Witton Bank Mines under Northwich were stabilised between 2005
- 23 - Proceedings of the 2012 Annual NAMHO Conference and 2009 by pumping over 1 million tonnes of grout into the existing excavations. On the surface the old mining areas, subsequently collapsed and used for chemical waste disposal, are now being turned into community woodlands. These extensive woodlands will eventually completely mask the industrial devastation of the 19th and 20th centuries leaving only the reconstructed and renovated Lion Salt Works at Marston as a memorial to mid-Cheshire’s historic salt industry.
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NOTICE
The 2013 NAMHO Conference is being held at Aberystwyth from 28th-30th June 2013. Full details are available on the conference website: www.NAMHOConference.org.uk
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