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CARBONIFEROUS LIMESTONE:
LANDFORMS AND QUARRYING
C
ARBONIFEROUS
LIMESTONE is a hard
sedimentary rock. Around 350
million years ago the UK was just
south of the Equator, moving
slowly north on a tectonic plate.
Geologists call this the
Carboniferous period, because
large deposits of coal were formed
at this time. Most of the UK was
covered in a shallow, warm
tropical sea which was full of life,
with coral reefs, abundant
shellfish, and other sea creatures.
The fossils of these animals
collected on the sea bed on and
around the reefs and were then
buried by layers of mud rich in
calcium. Eventually, these layers
became thick beds of limestone
and were covered by other
sediments. After millions of years,
they were lifted up as part of
mountain-building processes, and
appeared on the surface when the
rocks on top were removed by
erosion.
N
B
A
E
N. Ireland
G
C
D
F
0
200 km
Key
Area of Carboniferous limestone
A
National Park
F
AONB (Area of Outstanding Natural Beauty)
Figure 1: Areas of Carboniferous
GeoActive
Series
limestone
in the
UK 18 Issue 3
by John Davidson
Little or no water on surface
Often forms steep cliffs
in landscape called scars
A
Layers of
limestone
called beds
B
Regular cracks across
beds called joints
Distinct lines between
beds called bedding planes
Spring
Possible path of rainwater through limestone rock
Figure 2: Major characteristics of Carboniferous limestone
GeoActive Series 18 Issue 3
Carboniferous
limestone is
Fig 371_02 Mac/eps/illustrator
11 s/s
What are the characteristics
NELSON THORNES PUBLISHING
permeable.
This
means that the
of Carboniferous limestone?
Artist: David Russell Illustration
Carboniferous limestone is found
in many parts of the UK. It is
mainly composed of calcium
carbonate and is full of fossils.
Much of it is crystalline and very
hard. It is resistant to erosion and
forms upland areas. The major
places where Carboniferous
limestone can be found are shown
in Figure 1.
The limestone has distinct layers
called beds which are often
horizontal, but sometimes tilted
downhill. Over millions of years
the limestone has been affected by
earth movements and has
developed a series of cracks called
joints; there are also major breaks
in the rock called faults. Along
with the tiny gaps between layers
called bedding planes these
produce weak points in the rock.
Figure 2 shows the major
characteristics of Carboniferous
limestone.
Fig 371_01 Mac/eps/illustrator 11 s/s
NELSON THORNES PUBLISHING
Artist:
David
Series 18
Summer
issueRussell
Unit 371 Illustration
Carboniferous Limestone: Landforms and Quarrying © 2007 Nelson Thornes
This page may be photocopied for use within the purchasing institution only.
joints and bedding planes in the
limestone let water seep into the
rock and vanish underground.
Streams crossing onto the
limestone from other rock types
may also completely disappear
underground. For this reason the
ground surface in limestone areas
is often very dry.
Landforms of Carboniferous
limestone
Carboniferous limestone areas
have very unusual landscapes
which can be seen in several areas
of the UK, notably in the
Yorkshire Dales National Park.
Figure 3 shows some of the most
distinctive landforms.
Exposed areas of limestone can
form steep white cliffs, called
scars in Yorkshire, and large areas
of exposed flat rock called
limestone pavements. Other
features on the surface include dry
valleys, gorges and swallow holes
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Impermeable rocks
above limestone
Steep-sided
limestone gorge
Swallow
holes
Limestone
pavement
Limestone
cliff or scar
Stream
fuels in factories has increased rates
of limestone weathering since the
Industrial Revolution near large
urban areas. Figure 4 shows how
limestone pavements and caves are
produced by chemical weathering.
Stream
Spring (resurgence)
Joint cave
passage
Impermeable rock
below limestone
Bedding plane
cave passage
Cave with stalactites
and stalagmites
Figure 3: Distinctive landforms found in Carboniferous limestone areas
GeoActive Series 18 Issue 3
Fig 371_03 Mac/eps/illustrator 11Pavement
s/s
Rainfall
block
1
NELSON THORNES PUBLISHINGcalled a clint
Acidic
Artist: David Russell Illustration
rainfall lands
Weathered joint
2
on limestone
called a gryke
Rain dissolves
limestone
along joints
Limestone
pavement
3
Joint is deepened
and enlarged
as rain dissolves
limestone
As water moves
underground it can dissolve
and remove limestone along
joints and bedding planes to make caves
Cliff or
scar
In the UK
climate it can take
hundreds of years to
Spring
develop a limestone pavement
and cave system. As there is no water on
the surface, limestone pavements have very
little vegetation. Some plants and small trees
grow in the grykes
Figure 4: How a limestone pavement and cave system are made
GeoActive Series 18 Issue 3
(shake holes) where streams
go
Why does
Fig 371_04 Mac/eps/illustrator
11 s/s limestone form
underground. Below the
surface,
NELSON THORNES distinctive
PUBLISHING landforms?
extensive cave systems Artist:
have David Russell Illustration
All rainfall is naturally a weak acid.
developed with stalagmites and
Rainfall collects carbon dioxide as
stalactites. Eventually the water
it falls and this makes it dilute
moving underground along
carbonic acid. Although this is not
bedding planes and through
harmful to people, plants or
caves reappears as springs or
animals, the rainfall reacts with the
resurgences. The dry valleys and
calcium carbonate in the limestone,
gorges in limestone areas
turning it into a soluble form and
probably formed during the last
removing it in solution. This is
Ice Age, when the limestone was
called chemical weathering. Over
frozen underground and
hundreds of years the acid
meltwater streams flowed on the
rainwater can enlarge joints into
surface, eroding their river beds.
caves and create the distinctive
Some very steep-sided gorges
features of limestone areas. Where
may be the result of the roof of a
there is vegetation, acids in the soil
cave system collapsing.
can speed up this weathering
process. Acid rain containing
sulphur from the burning of fossil
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Cave systems underground in
Carboniferous limestone areas can
be very extensive. Stalactites form
from water containing calcium
carbonate in solution that drips
from the cave roof. Tiny amounts
of calcium carbonate are deposited
as the water drips and over
hundreds of years they become
needle-like stalactites. Stalagmites
can then grow up from the cave
floor to meet them. The cave
systems do not collapse because
Carboniferous limestone is such a
hard rock.
Quarrying of Carboniferous
limestone
There are over 1,500 quarries in
the UK, which employ over 30,000
people. However, most of the
Carboniferous limestone produced
comes from a few very large
quarries in the Mendips, Peak
District, Yorkshire and North
Wales. Nearly all of these are either
in National Parks or in Areas of
Outstanding Natural Beauty (see
Figure 1). Quarrying is an example
of primary industry. Solid rock is
removed from the ground and
either cut into blocks, crushed into
pieces or ground into a fine
powder.
The major uses of Carboniferous
limestone from quarries are shown
in Figure 5. Figure 6 shows how
the production of limestone has
generally increased over the last 45
years, particularly for the
construction industry.
Much of the limestone is crushed
into small fragments called
aggregates and used as a
foundation for roads or to make
concrete. One kilometre of new
motorway or by-pass can use up to
125,000 tonnes of aggregate from
a limestone quarry. That’s over
3,000 lorry-loads! With over 4
Series 18 Summer issue Unit 371 Carboniferous Limestone: Landforms and Quarrying © 2007 Nelson Thornes
This page may be photocopied for use within the purchasing institution only.
Crushed into
aggregates (fine and
coarse rock
fragments)
• Concrete
• Road building
• Foundations
Cut into blocks
• Building stones
• Statues
CARBONIFEROUS
LIMESTONE
• Smelting iron ore
• Fertiliser
• Water and gas treatment (neutralises
acids and helps remove sulphur
dioxide)
• Paint and
whitewash
manufacture
Figure 5: Major uses of Carboniferous limestone
million new homes required in the
UK over the next 20 years, the
demand for aggregate may double,
resulting in a high demand for
limestone.
The advantages and
disadvantages of limestone
quarrying
Carboniferous limestone is cheap
and easy to quarry and provides
nearly 70% of all the limestone
quarried in the UK. Many people
welcomed the development of
quarries in limestone areas, as they
provided permanent jobs at a time
when fewer and fewer people were
needed in farming. Forty-two
percent of all Carboniferous
limestone quarries are within or on
the edge of National Parks,
including the Peak District,
Yorkshire Dales, Lake District,
Snowdonia and the Brecon
Beacons National Parks. Figure 7
shows some of the positive and
negative impacts of limestone
quarrying.
In recent years, quarrying
companies have had to produce
plans to show how a quarry will be
landscaped and restored when it is
closed. The following are possible
uses of a closed Carboniferous
• made into a recreation area, for
example by being flooded to create a
lake
• sites for urban development such as
industrial estates
• Toothpaste
and face
powder
• Paper making
• restored to farmland with infill and
adding soil
• landscaped for nature conservation to
provide new sites for wildlife
Ground up into fine powder
• Making cement
• turned into a beauty spot, through
landscaping and planting of trees and
shrubs
limestone quarry:
• landfill site for dumping rubbish or
chemicals which can then be covered
over
• flooded to provide a water supply
lake
• developed as a museum or study
centre about the quarrying industry.
Conclusion
Limestone areas present a
fascinating geological history,
stunning contemporary landscape
for tourism and commercial
interest through quarrying. The
future prospects are of conflict
between environmental
conservation, industrial
exploitation and national tourism.
Million tonnes
1960
1970
1980
1990
2000
2005 (estimate)
20
65
45
78
48
76
Major uses of aggregates 2004
(crushed rock including
Carboniferous limestone)
• Road building/repairs 32%
• Housing 25%
• Offices and shops 14%
• Factories/warehouses 13%
• Other constructions 16%
Major uses of limestone in the UK
2004
• Construction (building stones/
aggregates ) 77%
• Cement manufacture 13%
• Industrial uses 8%
• Farming/fertiliser 2%
Figure 6: Production of limestone in the UK since 1960, and major uses
Positive impacts (advantages)
Negative impacts (disadvantages)
• Employment in quarries
• Quarries provide work for local
shops/services
• Quarry companies contribute to
local taxes
• Quarries can be landscaped and
restored when closed
• Noise from blasting and crushing
• Noise at night from night-time
quarrying
• Bright lights in countryside
• Dust
• Unsightly quarries in landscape
• Heavy lorries moving on country
roads
• Mud on roads
• Scars on landscape from closed
quarries
Figure 7: Impacts of quarrying in Carboniferous limestone areas
Series 18 Summer issue Unit 371 Carboniferous Limestone: Landforms and Quarrying © 2007 Nelson Thornes
This page may be photocopied for use within the purchasing institution only.
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Activities
H
1 On a copy of Figure 1, name
the National Parks labelled A to E,
and the Areas of Outstanding
Natural Beauty labelled F and G.
A
G
2 Using Figures 2 and 3, describe
the path of a water droplet
between points A and B on Figure
2.
3 Using Figures 4 and 5, describe
and explain the formation of a
limestone pavement and cave
system.
4 Using the internet and a search
engine such as Google Images, find
pictures of the following five
features of a Carboniferous
limestone area:
• Limestone pavement
• Swallow hole • Cave system
• Stalactites and stalagmites
• Limestone gorge.
5 Using Figure 5:
(a) List four industries that use
products from limestone quarries.
(b) Describe four uses of
limestone in your home or school.
(c) Give two reasons why
limestone quarrying is an
important economic activity.
6 Using the statistics in Figure 6:
(a) Draw a line graph to show
production of limestone in the UK
from 1960 to 2005.
(b) Draw a pie diagram to show
the main uses of aggregates in the
UK.
(c) Draw a pie diagram to show
the main uses of limestone in the
UK.
(d) Suggest two reasons why
production of limestone has
increased since 1960.
7 Figure 8 is a field sketch of a
limestone quarry in Yorkshire.
(a) On a copy of Figure 8, label
features A to I, with the help of
the list below.
• Crushing plant where stone is
crushed and sorted
• Overburden (soil and rock
removed to reach the limestone)
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E
B
F
C
D
I
Figure 8: Field sketch of a limestone quarry in the Yorkshire Dales National
Park
GeoActive Series 18 Issue 3
Fig 371_08 Mac/eps/illustrator
s/s
Ingleton11quarry
NELSON THORNES PUBLISHING
The quarry at Swinden produces 2.2
The quarry at Ingleton is in the heart of
Artist: David Russell Illustration
Swinden quarry
million tones of limestone per year and
directly employs 29 people. It has
recently benefited from a £16 million
upgrading programme and the quarry
has been deepened by 100 metres.
The quarry now has a new water
recycling plant and extensive
measures to reduce dust. The new
plant is hidden in the quarry floor and
over 10,000 trees have been planted to
help screen the site. The rail link
facilities have been upgraded, and
900,000 tonnes of products a year are
now moved by rail, saving 30,000 lorry
loads. Quarrying will continue until
2020 and plans have been made for
the area to then be restored, fully
landscaped and managed for nature
conservation.
one of the most popular areas of the
National Park for tourism. Here the
quarry buildings and machinery have
been re-sited and landscaped, with
artificial banks being developed to
screen the site, and nearly 3,000 trees
have been planted at a cost of £7
million. This has dramatically reduced
dust levels and also reduced the
impact on the landscape. The quarry is
an important local employer, in an area
where work in hill farming is in decline,
directly employing 15 people full time.
There are also local contractors who
drive the lorries, electricians who do
repairs and quarry workers, who all use
the local shops and services. Visitors to
the quarry are accommodated in
nearby hotels. When the quarrying
stops the area will be restored around
a central lake which will provide
facilities for recreation and nature
conservation.
Figure 9: Quarrying in the Yorkshire Dales National Park
• Quarry face where stone is
being removed
• Quarry offices
• Rail access
• Road access
• Site for future quarry extension
• Surrounding farmland and
pasture
• Trees planted to screen and
landscape site
(b) Describe two types of people
who would be in favour of this
quarry development. Suggest
reasons for their viewpoints.
(c) Describe two groups or
individuals who would be against
expansion of quarrying in
National Parks. Suggest reasons
for their views.
8 Using the information in
Figure 9, produce a fact sheet to
summarise the main features of
either Swinden or Ingleton quarry.
9 Produce a plan to show how
the quarry in Figure 8 could be
restored when it closes. Describe
the new uses you would propose
and provide a labelled sketch of
how the quarry would look.
Series 18 Summer issue Unit 371 Carboniferous Limestone: Landforms and Quarrying © 2007 Nelson Thornes
This page may be photocopied for use within the purchasing institution only.