Transcript Higher revision:

Higher revision:
Carboniferous Limestone
and
Land use conflicts
How are we going to revise
 2 stages:
 Stage 1:
 Carboniferous limestone
carousel(s).
 Stage 2:
 Land use…….
Carboniferous limestone
 Carousel:
 Working in groups of 3 go to one
of the numbered posters and pick
up your pen.
 Draw a large triangle on the
poster.
Carboniferous limestone
 Carousel task 1.
 You have 3 minutes to write down everything
you can about carboniferous limestone.
ONLY WRITE INSIDE THE TRIANGLE
Carboniferous limestone
 Carousel task 2.
 Now you are going to have 35 seconds at each
of the other posters. You do not write anything.
You are just gathering information.
Carboniferous limestone
 Carousel task 3.
 Change your scribe. Now you have another 2
minutes to add as much as you can to your
sheet but this time
WRITE OUTSIDE OF THE TRIANGLE.
Carboniferous limestone basics
 Carboniferous limestone was formed over 300
million years ago.
 The rock is around 80% calcium carbonate (CaC0 )
3
 Limestone is hard, resistant rock bit it is
fractured and divided into blocks based upon
horizontal bedding planes and vertical joints.
 These lines of weakness make limestone
permeable by allowing water to pass through.
Carboniferous limestone and
weathering.
 This means there is very little surface drainage
in limestone areas, but complex systems
containing water exist underground.
Carboniferous limestone and
weathering.
 This is the important part:
 Limestone is an alkaline rock.
 This makes it susceptible to attack by rainwater,
which is a dilute carbonic acid.
 Chemical reactions dissolve the rock, a process
known as carbonation, which is then carried in
solution by the water.
Features you need to know
6
1
2
Permeability
Rocks at A are?
Rocks at B are?
Features you need to know
Name the features
1 swallow hole/pothole
2 pavement
3
5
3
4
scar
4
scree
5 cave/cavern
6
gorge
Carousel 2
 Now you are going to be given a feature of
carboniferous limestone and you must try and
complete as much of the answer as possible
in 3 minutes.
Feature: Limestone pavement
1. A Limestone pavement is formed due to chemical weathering.
2. The limestone is often bare and scratched due to the advance of a
glacier.
1. Limestone is a hard rock, but it is also an alkaline rock.
1. This means that it is badly effected by carbonic acid, found in rainwater.
1. When the two meet a process called carbonation occurs and this wears
away the rock.
1. Limestone is an alkaline rock.
2. It is a hard rock but it reacts with
acidic rain and dissolves away.
3. Little material is left on the surface to
form soil.So it appears as bare rock.
6. The Limestone’s surface is covered in lots of cracks.
7. Over time water has laid in these cracks, slowly dissolving the
limestone.
8. This has made them deeper and wider.
The flat bare surfaces are called
CLINTS and the large cracks
where the water builds up are
called GRYKES.
Geography
CLINT
GRYKE
Tom Abbott, Biddulph High
School and made available
through
www.sln.org.uk/geography and
Limestone Pavement on Scales Moor
Formation of a Cavern
Chemical weathering, rock structure and permeability are all important
factors in the formation of a cave.
Bedding planes and joints are areas of
weakness which are dissolved by
chemical weathering. Water can pass
along bedding planes and down joints
The carbonic acid in the water reacts
with the calcium carbonate in the
limestone, dissolving it and removing it in
solution. This forms tunnels along the
bedding planes and joints.
Chemical weathering continues and a
cave forms over a long period of time.
The action of the water also helps to
remove rock.
*** This process normally takes many thousands of years, but was
speeded up significantly by the action of melt water from glaciation***
Limestone Cavern with Stalactites and Stalagmites
Percolation
Stalactite
Pillar
Straw
Stalactites
Stalagmite
In Northern
England
stalactites only
grow by about
7.5mm per year!
• Water which drips into caverns contains calcium carbonate that has dissolved
from the limestone on it’s passage through the rocks. As the water percolates
through rocks and drips from the cavern roof, the different atmosphere causes
it to lose C02 and a white mineral known as calcite is precipitated out. Some of
the water evaporates,, redepositing the calcium carbonate. This forms long thin
fingers of dripstone deposits, known as stalactites.
• Where water drips from the ends of these and lands on the cavern floor a
shorter, more rounded dripstone deposit will be formed. This is known as a
stalagmites.
• Where stalactites and stalagmites join, a pillar is formed.
Limestone Cavern with Stalactites and Stalagmites
Swallow
hole (sink)
Swallow Holes & Intermittent Drainage
Where joints have been enlarged by solution water can seep
downwards. A rock such as limestone which allow water to pass
through is said to be permeable (A rock which doesn’t let water
pass through is impermeable). Swallow holes are formed by the
persistent widening of joints, for example where a stream leaves
impermeable rock and meets permeable limestone, creating a
disappearing stream.
Thus on an O.S. map there will be very few streams marked on the
map where the rock is exposed limestone. Where the rock is a
mixture of limestone and impermeable rocks, streams disappear
down swallow holes and then reappear at resurgence
streams/spring. This is intermittent drainage.
In the Yorkshire Dales Fell Beck plunges underground through Gaping Gill
and down a 110m waterfall.
SD7572
Fell Beck travels through 11km of underground tunnels, before emerging at
Clapham Beck Head – as a spring or resurgence stream.
Gorges
There are varying explanations of the formations of gorges.
Gorges were probably caused by a roof collapsing in areas where there has
been active underground erosion of caverns. This may have followed a
glacial meltwater surges when massive amounts of water flooded
limestone areas. Essentially the joints and bedding planes were enlarged
and as a results passageways, shafts and caverns formed and eventually
collapsed, leaving a steep sided gorge.
An alternative explanation is that the gorges are the outcome of
retreating waterfalls, formed as glacier meltwater saturated the
landscape at the end of the ice age, rising the water table level.
Gordale Scar is thought to be an example of a gorge, although it is also
believed that melt water streams after glaciation played a significant role
in it’s formation.
Gordale Scar
Rural land resources:
Loch Lomond.
 How does the landscape provides social and
economic opportunities?
 Glaciation creates upland areas with sharp peaks
and steep slopes, devoid of quality soil because it
has been scrapped bare by the action of glaciers.
These conditions are used in Loch Lomond and
The Trossachs for sheep farming as the animals
are well adapted to live in such conditions.
Government and EU grants have helped to make
sheep farming profitable. Deer is can also live in
these conditions and are found on these slopes;
the meat can be sold to other EU countries to
provide money for the area. Tourists come to the
area to hunt the deer too.
 Further down the glaciated slopes as the land
becomes flatter, forestry is possible. Trees
can grow in the cold and wet climate of Loch
Lomond and the Trossachs and on the poor
quality soil which is found. Non- native
coniferous timber brought economic
opportunity to the Area but these are being
replaced by native species e.g. north of Loch
Katrine which can be equally marketed for
timber.
 In Loch Lomond, the steepness of the area
coupled with the high annual rainfall means
that HEP is possible. Corries and hanging
valleys in the area provide natural reservoirs
which can be dammed and the steep sides
provide potential energy required to turn the
turbines. The station is able to generate
electricity to the local area and beyond. Loch
Sloy above the banks of Loch Lomond
provides water for the HEP. Loch Lomond and
Loch Katrine also provide water supply to
nearby urban areas, such as Glasgow.
 The flat floor of the U shaped valley also
allows opportunities for communication links
like the A82, which in turn can lead to
opportunities for economic and social
developments as better road links allows
more people to visit and provides transport
links for the timber industry. Visitors to the
area offer economic opportunities such as
the growth of B&B and hotels. This can help
boost the economy of areas such as Luss.
 The glaciated landscape of Loch Lomond and the
Trossachs is very dramatic with corries, hanging
valleys and steep slopes. Many people can
therefore do various activities such as mountain
biking, hill walking and sightseeing hence the
area offers many social opportunities. Loch
Lomond and the Trossachs also offers access to
a number of Munros, such as Ben More, that the
public can walk and climb. Loch Lomond offers
opportunities for many water sports such as
canoeing, sailing, water skiing and fishing and
other social pursuits.
 Conservation is another social opportunity in
Loch Lomond. At Loch Lomond Shores, an
education centre helps to educate people
which can expand their understanding of the
environment by taking part in the education
programmes that the Ranger Service
provides.
Land use conflicts
Conflicts in Loch Lomond
 Area popular with tourists but is also bounded by other landowners reach
with their own aims and rights so conflicts can occur
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Stalkers v walkers
Loch pollution from boats
Disturbance of fishing and water birds by jet skiers and other users of the
loch
Increased problem of littering the lochside and footpaths
Erosion of the footpaths (West Highland Way) and cycle routes
More and more people using the glens and the high tops so disturbance of
wildlife.
Deer stalking v regeneration of forestry
Deer fencing v visual impact
Increase in cars causing congestion and erosion
Increase risk of fire.
Military aircraft v pollution.
Rural land resources:
Loch Lomond.
 What conflicts can arise in this area?