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GeologyAbout 350 million years ago, most of the Peak District was under a shallow tropical
sea. The fossilised remains of the plants, shellfish and corals in this sea have
formed what is now the Limestone that lies under the White Peak area of the Peak
National Park. Over the next few million years, sands, gravels and mud were deposited
to form the Millstone Grit and Shale of the Dark Peak. Movements in the earth's
crust, caused cracks in the limestone and hot gases and liquids crystalised in
these cracks to form veins of minerals. Mineral extraction (quarrying and mining)
has been an important industry in the Peak District for hundreds of years.
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building stone and in making mortar and cement. The limestone in this area is
often very pure (high in Calcium Carbonate) and has many uses. It was used in
agriculture and limeburning for use on the land, was mentioned in 1521. Lime
kilns (for burning limestone) were a familiar sight in the Peak District. Lime
was also used in lead smelting. The cutting of canals and later the opening of
the Cromford and High Peak Railway, helped the movement of lime out of the area,
to be used in building and other industries.
There are 12 main active quarries in the Park. The largest quarries are:- Hope (owned by Blue Circle), Tunstead/Old Moor (owned by Buxton Lime Industries Ltd a subsidiary of Minorco, formerly owned by ICI), Ballidon (owned by Tilcon), Darlton and Eldon Hill. Limestone from the Peak District is supplied to the East Midlands, North Western and Yorkshire regions. During the 1980s, limestone was increasingly used as aggregate. The limestone quarried from the Peak National Park in 1989 was used as follows:-
The feeling has grown that this may be an extravagant use of a product from a National Park, and after reaching a peak in 1991, the production of limestone has been decreased.
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 Magpie Mine near Sheldon |
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From the time of the Romans until the end of the 19th century, lead mining was
very important. Lead is extracted from galena, one of the minerals found in limestone.
It is found both in vertical veins in the rock (rakes) and in horizontal veins
(flats).
From the 12th century onwards, the mining industry grew. A large number of mine
shafts were sunk, sometimes through hundreds of feet of shale or sandstone, to
reach the limestone where veins of lead ore could be found. The lead mining industry
reached its peak early in the 18th century, when there were at least 10,000 miners
at work. As mines were dug deeper, flooding became a problem and much effort
was put into draining them by means of soughs (drainage tunnels) and pumps.
By the 1870s lead mining was dying out. Lead could be obtained more cheaply from
other places. Mines gradually closed, although one last mine at Darley Dale was
worked until 1938.
Today, the Peak District National Park is a major source of a number of other
vein minerals including, fluorspar, barytes and calcite.
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The veins where galena was found contained other minerals as well. Until the
beginning of the 20th century, miners used to throw away the other gangue (or
waste) minerals onto spoil heaps. It was then discovered that one of these minerals,
fluorspar (Calcium Fluoride) was important in steel making and so the old spoil
heaps and lead workings were re-examined.
 Fluorspar |
 Dirtlow Rake, Bradwell Moor |
1. By underground mining - Fluorspar has been mined extensively
under Longstone Edge. Milldam Mine at Great Hucklow has been developed
since 1987 and is now the primary source of fluorspar in the Peak
Park. The ore mined underground is the highest grade (containing
40% fluorspar)
2. By opencast mining - from a variety of sites ranging from large open pits
(such as Dirtlow Rake on Bradwell Moor) down to small sites worked by independent
companies, a few men (known locally as tributors), or even local farmers in
their spare time. These sites are normally backfilled and restored (either
as fields or as areas for wildlife) after they have been worked out. The ore
mined by the opencast method is of a lower grade (15-20% fluorspar)
3. By reworking old spoil heaps (hillocking) -This method of working increased
in the 1960s and 1970s but is mostly finished now.
The major company involved in mining and processing fluorspar is Laportes.
Ore is processed at Laportes' Cavendish Mill Plant, near Stoney Middleton.
Typical annual output is about 60,000 tonnes of 'Acid grade' fluorspar (97%
calcium fluoride for use in the chemical industry). The UK output of fluorspar
fell in the early 1990s (to about 53,000 tonnes in 1994) but has increased
since then. The Peak District National Park accounts for virtually all of the
UK supply.
Processing fluorspar involves crushing the ore finely and separating out the
minerals. The waste is then disposed of as a slurry in tailings lagoons. However,
such lagoons have an unacceptable environmental impact. One alternative method
of disposing of the waste, is to use it as a cemented backfill and fill up
the mine as underground working is completed. This process is in use at Milldam
Mine.
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 Calcite |
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Barytes (Barium Sulphate) is another mineral that is found in veins with lead
ore and fluorspar. About 20,000 tonnes of barytes is processed each year at Cavendish
Mill and used as a lubricant in oil and gas drilling, in paint manufacture and
in other industrial products.
Back
to top
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Calcite crystals (Calcium Carbonate) are used for ornamental finishes, chippings
for flat roofs and in wall surfaces. They also give the sparkle to the white
lines painted on roads and when finely ground, can be used as filler in plastics.
Back
to top
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Silica Sand is extracted from one pit in the Peak District.
Fireclay was extracted until recently but this has now ceased.
Seismic surveys to detect the presence of OIL and GAS have been
carried out. One exploratory well was drilled at Wessenden, in the extreme north
of the Peak National Park, in 1987, but nothing was found.
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Many of the quarries and mines in the Peak District were operating before the
area became a National Park. The National Park boundary was drawn so that it
excluded many of the main limestone quarries in the Buxton area (that is why
the Park is an odd shape).
The policies on mineral extraction are decided by the Planning Authority for
the Park, in liaison with local and national government organisations. These
policies are set out in the Peak National Park Structure Plan . A replacement
of the old 1979 Structure Plan, was adopted in 1994.
The Park Authority also keeps in touch with bodies such as the District Council
Environmental Health Authorities, the National River Authorities, the Air Pollution
Inspectorate and the Mines and Quarries Inspectorate , who have responsibility
for such matters as noise nuisance, water and dust pollution and safety within
quarries.
Although quarries and mines spoil the landscape and may pollute the land and
the air, some of the minerals cannot be found easily in other areas. The industry
is also important to both the local economy (providing jobs for local residents)
and the national economy. For these reasons four main questions must be asked
in judging any proposals for new mines or quarries or for extensions to existing
ones:-
1. Is there a real need for the product, either locally or nationally, or could another product be used instead? i.e. Stone other than limestone can be used for roads.
2. Is there another source for the material that would be a practical alternative? i.e. Limestone can be found in other parts of the country that are not National Parks.
3. What will be the effect on traffic? Will even more heavy lorries be using overcrowded roads? i.e. Moving stone by railway may be a possible alternative.
4. How far will the local residents, landscape and environment be affected? The Park Authority now insists that landscaping schemes and restoration work must be agreed as part of any new proposal.
The following two case histories show how these four questions
are considered in deciding whether to allow any extensions or new
developments in the mineral industry:-
Case history;- Topley Pike Quarry (1985)
Topley Pike quarry has been worked since about 1910 with several extensions
since then. It produced 500-750,000 tonnes p.a. of limestone for aggregate.
It employed about 70 men.
Proposal: To extend 19 acres to the south west and quarry a
further 14 m. tonnes over 16 years. Site to be restored after 16 years.
Tarmac's arguments for the proposal
- it would provide enough money for landscape improvements and restoration work
- limestone would be carried by train, not clog up roads
- the quarry is right on the edge of the Park
- without an extension, present work would be spread over longer period and present quarry would be exacavated below the water table.
Park Authority arguments against the proposal
- no national or local need for more roadstone
- alternative sources outside the Park for such stone
- extension would affect the landscape, particularly the village of Earl Sterndale
- dust would have a bad effect on wildlife in the SSSI
The proposal was refused (in 1985) by the Secretary of
State after an appeal and public inquiry
Case history - Milldam Mine (1987)
Proposal: To open new underground fluorspar mine on
site of old lead mine in Great Hucklow (then a scrap yard)
Laportes' arguments for the proposal
- Established national and local need for mineral
- no alternative source of ore except in National Park
- workings will be made visually acceptable
- no reasonable alternative site. Proposed site would need restoration anyway
- proposal would provide employment
Park Authority concerns
- disturbance to village of Great Hucklow during construction and during life of mine
- proposal would require extension to working life of Blakedon Hollow Lagoon and of Cavendish Mill
- delay of 10 years in final restoration work at Milldam Mine
The proposal was granted (in 1987) by the Board
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