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GEOGRAPHY PAMPHLET – Year 7 ERW – May 2018

GEOGRAPHY

PAMPHLET

Year 7


TABLE OF CONTENTS

A- Course Summary Notes

B- Glossary


A- Course Summary Notes


The geography exam at the end of Year 7 will be based on the work we have covered in class this

year as well as the work covered in Year 6.

Year 6 saw the start of the Common Entrance Syllabus. Last year, we covered two modules:

- Tectonic Processes - Ordnance Survey Mapwork (start of)

In Year 7 we have built on this with the following modules:

- Ordnance Survey Mapwork (finish) - Weathering - Geomorphological Processes (the study of erosion, transportation and deposition through

rivers and coasts)

The fieldtrip this term WILL NOT be examined.

All topics have been comprehensively covered and the written handouts given to the children during

the course of the two years will form the basis of the revision notes. These can be found in their

green class books. Since Year 6 most, if not all the children are now onto their third/forth book. All

books (with the exception of the current working books), have been taken away by your son /

daughter for safe keeping. My classnotes can also be found on the revision section of the school

website.

The exam itself will be 1 hour long.

It is the intention in Year 7 to start introducing as many past paper Common Entrance type questions

as possible into the exam paper. These will be supplemented by those formulated by the geography

department. The types of questions will range from one word answers, multiple choice, paragraph

answers, diagram drawing. Extended written answers will be needed for the case studies covered.

The intention of the exam in Year 7 is to ensure that ALL the work covered has been understood. It

is impossible to include questions on everything covered but I will guarantee that every module will

be examined.

If your child has started with us in Year 7 then a modified paper will be given which covers the work

from just this year.

Your children must be fully equipped with all the stationary needed to sit a Geography exam (pen,

pencil, colouring pencils, ruler and rubber). These will not be provided by the school.

J.E.R Williams

Head of Geography


Weathering

To fully understand the process of weathering, and to be able to give it a

definition, we have to be mindful of how it relates to erosion.

Both WEATHERING and EROSION involve the process of wearing down. The

difference with the processes is the way in which the wearing down takes

place.

Weathering

Definition: The wearing away in one place. What we call “In Situ”.

Example: A garden shed if untreated will slowly break down because of the

elements (wind, rain, sun etc.). Eventually it will break up and collapse in the

same place as it originally stood.

Erosion

Definition: The wearing away by a moving force (water, wind and ice). The

material is eroded, then transported and deposited away from the point of

erosion.

Example

Coastlines

Rivers


Physical Weathering: Freeze-Thaw Weathering

Freeze thaw weathering has split this rock in two

This crack has been made wider by Freeze-thaw weathering

Eventually rocks get broken down to be

loose material like this.


Freeze Thaw Weathering

Frost Shattering

Water fills the crack in the rock

The water freezes by approximately 11% and

the crack is made wider. The water then melts

when the temperature rises above 0˚C.

This process is repeated until the rock

breaks into several pieces.

The process of freeze thaw weathering will be a lot

quicker in softer rocks such as sandstone than in

harder, more resistant rocks such as granite. It will

also be quicker in areas where Freeze Thaw happens

regularly during the winter months.


Chemical Weathering

This is caused by the action of Water. Ordinary rainwater contains small

amounts of acid, especially these days where pollution in the atmosphere is

absorbed into the rainwater. These pollutants come from things like traffic

fumes and industry.

When this rain comes into contact with certain rocks the acids will attack it and

cause it to crumble away. The results of this can be seen on Buildings, statues

and in church yards where stone gets worn away or pitted.

Sedimentary rocks, such as limestone and chalk are particularly at risk to this

type of weathering.

Carbonic acid in the rain falling on limestone, turns it into calcium

bicarbonate, which is soluble in water.

Limestone gravestones and steps and pavements are also vulnerable as

the acid water falls into the cracks and attacks a large surface area.

The situation becomes even more of a problem in warm and wet conditions

where the process is speeded up.

A new headstone before weathering takes effect

After a number of years, this is what happens


Other examples:

Biological Weathering

The process of Biological Weathering is caused by the action of PLANTS and

ANIMALS.

Animals:

Burrowing animals can break up the rocks eg. Rabbits, badgers and moles. We

have also looked at the impact burrowing animals have on the foundations of

buildings.

Plants:

Plant seeds can fall into cracks in the rock. This provides the ideal conditions

for a seed to germinate. A germinated seed will grow to become a strong plant

which will grow out through the crack. All strong plants are dependent on a


strong root network which pushes downwards through the rock splitting it

further. The pressure the plant exerts on the crack will force it wider until

eventually the crack will split and the rock will fall to pieces.

Tree roots will also have a similar impact as they often spread well away from

the tree. They too will exert pressure on the cracks as they grow, causing them

to widen. We have looked at the impact of this on paving stones on

pavements, tarmac driveways and on roots which encroach on building

foundations.

The impact of tree roots, weeds, fungus and animals


Biological Weathering

A seed blows into a crack in a rock. The

crack is damp and sheltered. The seed

grows.

The tree grows and splits the rock

The roots grow down into the crack. The

roots get bigger as the plant grows

Animals like moles burrow

underground. They can loosen

rocks as they dig.


Volcanoes and Earthquakes Natural Disasters

A lot of the geography which we look at and hear about in the news is the results of

‘NATURAL DISASTERS’.

A ‘Natural Disaster’ is basically described as a freak of nature. It is going to happen or it has

happened and there is nothing we as humans can do to change that. We cannot stop it but

we can try and limit the damage or soften the impact in some way.

Examples of natural disasters include:

Volcanoes

Earthquakes

Flooding

Storms In Britain we are fortunate that earthquakes and volcanoes are rare and usually very minor.

Britain is more likely to be affected by the other two in the list - flooding and storms. The big

difference being that what we are used to rarely kills a lot of people. Where volcanoes and

earthquakes are common the death rate is invariably high with each event.

It is not so much the power of the earthquake or volcano that kills it is the number of people

living in the area. What we call the population density.

Example : In San Francisco in the USA in 1989 there was a very powerful earthquake. Sixty

seven people died and over three thousand were injured.

Compare this to :

An Indian earthquake in 1993 which was much less powerful than the one in San Francisco

yet 20,000 people died and hundreds of thousands were injured. Close to where the

earthquake happened a third of the population of one town died.

Watching disasters

With the wide range of media now at our fingertips (TV, internet, radio and newspapers) we

have no excuse of not knowing what is going on in the world. Depending on the scale of

disaster and its relevance to us in the United Kingdom coverage can vary but there will

always be something to report. The above mentioned earthquake in India did not make the

front page news in our newspapers but the South East Asian Tsunami in 2004 made the

headlines and front pages for at least a week.


The location of volcanoes and earthquakes

Some of the common things said by children when they study volcanoes and earthquakes

have included the following:

I think that earthquakes and volcanoes only happen in hot places. The heat cracks the ground

They only happen in poor countries as the people there do not have the technology to prevent them

I think that they will only happen on large continents. Britain is an island, and we don’t get earthquakes and volcanoes

I think that we can get earthquakes and volcanoes everywhere and anywhere – its just a question of luck

Hopefully by the end of this topic you will see why these comments were made but more

importantly you will agree that with subject knowledge each statement is in fact untrue.

When you look at the three maps which you have completed:

‘Global distribution of earthquakes’ ‘Global distribution of volcanoes’ and ‘The worlds major plate boundaries’

You will see that there is a pattern which emerges.

Earthquakes and volcanoes don’t just happen anywhere. They tend to occur along lines, which we call BELTS.

They often occur together areas which we call ZONES OF ACTIVITY

They occur in the oceans as well as on the land

The two most important belts are the one which circles the Pacific Ocean – PACIFIC RING OF FIRE and the one which comes down the middle of the Atlantic Ocean – MID ATLANTIC RIDGE.

It has taken scientists many years to try and work out why this is the case and they came to

the conclusion that:

The earth’s surface is cracked into pieces like an eggshell. We call these pieces PLATES

The plates are constantly moving

The plates are named and can either be land (continental) or sea (oceanic)

These movements cause earthquakes and volcanoes to occur along the cracks

To understand why the earth’s surface is split into plates and why they move and why we

get earthquakes and volcanoes as a result of this, we must look at the ‘structure of the

earth’.


KEY

______ Plate Boundary

Direction of mov

ing plate

The World’s Major plate boundaries

KEY

______ Plate Boundary

Direction of

moving plate


The Structure of the Earth

The earth is believed to have formed 4,600 million years ago. Since then it has been slowly cooling

down. We know this for sure as around the outside a CRUST has formed, which is a layer of solid

rock. The process which has caused this is similar to that which causes skin to form on top of a bowl

of custard as it cools.

Compared to the rest of the earth the crust is very thin and has split into separate pieces known as

PLATES. We know that some of these plates are as large as continents whilst others are much

smaller. What will always stay the same, however, is that where they meet each other, we call it a

PLATE BOUNDARY and this is where earthquakes and volcanoes happen.

There are two types of crust. The OCEANIC crust is a thin layer that covers the earth’s surface and

forms the ocean bed. The CONTINENTAL crust sits on top of it and forms the continents. It is

important that we accept that there are three main differences between the plates.

OCEANIC

CONTINENTAL

Heavier / denser

Sinks

Continually renewed and

destroyed

Rock type – basalt

Lighter

Floats

Permanent

Rock type - granite

The layer beneath the crust is called the MANTLE. The plates float like rafts on top of the mantle,

where the rock is so hot that it is molten (like treacle). Heat from the solid CORE (approximately

5500oc) rises through the mantle creating CONVECTION CURRENTS which cause the plates above

them to move very slowly – usually no more than a few centimetres each year. The plates can either:

move apart, collide or slide past each other.


Activity at plate boundaries

Over a long period of the earth’s history we know that plates have been moving apart at a very slow

rate (as little as 1 or 2 cm per year).

The movement of the continents is called CONTINENTAL DRIFT and

The movement of the ocean floor is called SEA FLOOR SPREADING.

The structure of the Earth

Plate movements


At plate boundaries the plates can do one of three things:

They can move towards each other

They can move away from each other or

They can slip past each other.

Destructive plate boundaries

A destructive plate boundary is when oceanic crust moves towards continental crust. As the oceanic

crust is heavier it is forced downwards. The point at which it is forced down is called the

SUBDUCTION ZONE. As it is forced down pressure increases, which can trigger extremely violent

earthquakes. At the same time the heat produced by friction from the rocks rubbing against each

other turns the sinking crust back into a liquid rock called magma. The hot magma tries to rise to the

surface and when it does so there will be a volcanic eruption.


Constructive plate boundaries

Constructive plate margin

A constructive plate boundary is when two plates move apart e.g The North American Plate

moving away from the Eurasian Plate. When this happens a gap appears between the two

plates. Lava deep within the earth will see this as a weak spot/exit point and pressure will

be released through it. Lava will rise through this gap. How quickly it does this will depend

on the pressure which is forcing it out. What will always happen however, is that when the

lava makes contact with sea water on the bed of the ocean it will quickly cool and harden. In

this process the lava creates new oceanic crust and forms the MID-ATLANTIC RIDGE.

If we were able to drain the water from the Atlantic we would be able to see that running

right down the middle would be a range of mountains. It is this range of mountains that we

call the Mid Atlantic Ridge. Iceland forms one of the islands along this ridge.


Conservative plate boundaries

The two plates move in opposite directions

The plates become locked together and movement is restricted

Pressure builds up until the plates suddenly give way

The amount of pressure released will dictate the size of earthquake

Sometimes smaller slips can give small quakes which lead up to a big one

Other times an earthquake can be followed by others which can be equally as

powerful or smaller. We call these AFTERSHOCKS.


The different parts of a volcano

Predicting and preparing for Volcanoes

There are a number of measures a country can take to PREDICT volcanic activity and

eruptions, and many steps can be taken to prepare for them. We must remember however,

that they are natural events and therefore unpredictable in what they bring. Because of this,

however well prepared a country may think they are they may still be caught out. What we

can be sure of though is that whatever measures are adopted, they require a great deal of

money and organisation. It is these two factors which make it easier to enforce in wealthier

countries and more of a challenge in poorer, less developed countries. It would be true to

say that the population of poorer countries in volcanic areas can rightly feel the most

vulnerable.


Methods of predicting

Predicting a volcanic eruption is made easier by the fact that the volcano may well give

some clues that there is going to be some action about to be unleashed.

A volcano will begin to change shape as the magma rises within it. At times we can

see this with our eyes but it is more accurately measured with satellite imaging. Tilt

metres are also used for the same purpose.

Scientists can place sensing equipment on, or around the volcano to measure the

level of sulphur dioxide and carbon dioxide being released by the volcano. The

greater the level of gas the greater the likelihood of an eruption.

Seismometers can be placed on the slopes of the volcano. Before an eruption it may

well be that a series of earthquakes will occur which the seismometer will register.

The better the information about the likelihood of an eruption the better as local people can

then be evacuated. Using a combination of the above methods has allowed scientists to

successfully predict eruptions, particularly in developed countries where the appropriate

scientific equipment is available. In developing countries, money is not always available for

such equipment.

Despite huge strides in science it is still not easy to predict exactly when, and how severe a

volcanic eruption will be. There are however, several measures which can be taken to

prepare for such an eventuality.

Ways to Prepare

Authorities can evacuate local residence based on scientific prediction and

knowledge of how far lava flows have reached in past eruptions. This may be

recorded on a hazard map.

Many settlements on the sides of volcanoes have trenches built above them which

will divert the lava flows either side of the settlement.

During an eruption water can be sprayed on slow-moving lava to cool it down to

slow its progress, especially if it is heading for a settlement. In a similar way lava

flows can be bombed in order to divert the flow. This method has been done by the

Italian airforce on Mount Etna.


Why people still live in or near volcanoes and earthquakes zones

Despite the dangers of living near a volcano, people continue to live in these areas for a

number of reasons:

They cannot afford to move or live anywhere else. This is particularly the case with

people in developing countries.

They have always lived there and that is where they want to stay. Family members

are there and family bonds are difficult to break.


People believe it will never happen to them. They have not experienced a volcanic

eruption or an earthquake in their life time so what’s to say it can’t stay that way?

The enticement of a good job with a big salary might force individuals to take the risk

and move to a danger zone. For example, a banker in London might be asked to go

and do a similar job in Tokyo or Los Angeles for a set period of time. The money is

too good to turn down yet both places are known earthquake/volcanic areas.

Why people specifically continue to live near volcanoes

Interest in volcanoes generates tourism and therefore boosts the local economy.

Geothermal energy can be produced from the rising steam, for example in Iceland

and New Zealand people heat their houses and run industry using this method.

Fertile soil is produced by the weathering of volcanic ash. The soil is particularly good

for grapevines. This is the reason why Sicily is such a good wine producing region.

Minerals such as gold and diamonds can be found in the area.


The location of the South East Asia Tsunami and its

impact on the surrounding countries

The location of the South East Asia Tsunami

on a world scale


Predicting and preparing for Earthquakes

There are a number of measures a country can take to PREDICT earthquakes, and many

steps can be taken to prepare for them. We must remember however, that they are

natural events and therefore unpredictable in what they bring. Because of this,

however well prepared a country may think they are they may still be caught out. What

we can be sure of though is that whatever measures are adopted, they require a great

deal of money and organisation. It is these two factors which make it easier to enforce

in wealthier countries and more of a challenge in poorer, less developed countries. It

would be true to say that the population of poorer countries in ‘danger zones’ can

rightly feel the most vulnerable.


Methods of predicting

Predicting earthquakes remains extremely difficult. ‘Where’ and ‘When’ remain key

questions even though we know that they will be triggered somewhere along plate

boundaries. The following methods will help to assist making predictions.

Regular, small earthquakes often occur along conservative plate boundaries as the plates slide past each other causing friction and a build-up of stress which periodically gets released. If these small earthquakes stop it may well be a sign that the plates are locked. Another sudden movement may unlock the plates and a larger earthquake may be felt. In the hours and minutes before a large earthquake, smaller earthquakes called ‘foreshocks’ may be felt, indicating that a big one is on its way. These shock waves are measured using a seismometer.

Scientists have noticed a gas called Radon is often released in the hours before an earthquake. Monitoring for this gas along a fault line may help to predict the location of an impending earthquake.

Certain animals are very sensitive to movement within the ground and can feel and react to foreshocks that humans cannot feel. It took over an hour for the Tsunami wave to hit the coast of Thailand, but local elephants had already broken free of their chains and headed to higher ground as they felt the earthquake.

Preparing

In developing countries earthquakes that strike densely populated areas can kill thousands

of people. Buildings in these countries are often built quickly and without following proper

building regulations. The result is that they often fall in on themselves. We call this

pancaking.

Developed countries in contrast can better afford to protect their buildings and to limit the

damage and threat to life.

A building made of brick, stone or concrete is not particularly flexible, but if it is encased in a steel frame or shell it is able to twist and bend during an earthquake (cross bracing).

In developing countries wood is often used to construct buildings. This is good in the fact that they are flexible and less likely to collapse but problematic in the fact that they can quickly catch fire and spread. Where the emergency services are not particularly efficient this is devastating. In developed countries buildings are often equipped with sprinkler systems which deal with fires before they get a chance to spread.


To enable building to absorb much of the power of the shock waves they can be built on rubber foundations. These allow the building to move with the quake instead of collapsing.

A building can be protected by installing a counterweight on the top floor. This ensures the building stays stable even when the ground is shaking. Counterweights are expensive to install and are therefore only used in developed countries in buildings such as office block which are often covered in glass. Reinforced glass will obviously have to be used as well in order to deduce death and damage.

Earthquake drills can be practised in schools and offices (like our school fire drills)

Computers can cut off gas supplies as soon as an earthquake breaks, to minimise fires.

Tsunami walls and shelters can be built in areas prone to this kind of threat.

Families can keep survival kits in their homes.

Factors determining the severity of damage

A number of factors determine the severity of damage caused by an earthquake or volcano:

The type of plate boundary. A destructive (oceanic v continental) boundary causes the most violent

volcanoes.

The proximity of a volcano or an earthquake’s epicentre to a large settlement. Those situated near large cities where population is dense cause more deaths than those in less populated areas.

The proximity of the earthquake’s focus to the earth’s surface. The closer the focus the more powerful the earthquake.

The wealth of the country in which it happens. A developed country can afford scientific prediction instruments, buildings that are designed to withstand earthquakes, a quick reaction force and good medical care for the injured.

The time of day when the volcano or more particularly the earthquake strikes. If it strikes when people are in bed or congregated in one area, for example, at rush hour, its results can be more devastating.


Comparing an earthquake or volcano in a developing country with one in a

developed country

The death and injury levels will be greater in a developing country as the hospitals and

emergency services are less efficient.

The cost of repair may be greater in a developed country as the infrastructure is more

developed.

More death and destruction may occur around volcanoes in a developing country as many

subsistence farmers will farm close to the volcanic cone in order to benefit from the fertile

soil.

The amount of aid received is probably going to be greater in a developing country as the population’s needs are greater.

Greater scientific monitoring and data gathering will occur in developed countries. Therefore prediction will be more accurate in developed countries, although predicting an earthquake is very difficult.

Emergency action plans are less likely to be prepared or practised in developing countries. A good emergency plan has three stages.

PREDICT – PLAN – TAKE ACTION.

Secondary effects may be worse in a developing country, as the level of poverty means that disease is more likely to spread.


Rivers and Coasts

Rivers, ‘From Source to Sea’

The main features of a river basin

A DRAINAGE or RIVER BASIN is an area of land drained by a river. The higher land which

forms the boundary of the river basin, and which separates two river basins, is called the

WATERSHED.

Most rain falls in mountainous areas. Rain falling on higher land near the watershed collect

in small pools called SOURCES, and from here the water will flow quickly downhill either

through the topsoil or it will cut a CHANNEL for itself. This channel is called a TRIBUTARY

and as it continues its journey it will increase in size. The reason for this is that the stream

will join up with other streams. The point at which they meet is called a CONFLUENCE.

As the journey continues so the stream will become bigger and so it becomes an established

river. The river will then continue its journey to the sea. The point of entry into the sea is

called the MOUTH.

From its beginnings at the source to the end of its life at the mouth the river will change, not

only its own character but also that of the land which it flows across. It will do this by three

processes:

Erosion

Transportation and

Deposition


The Three Stages of a river’s journey

All rivers are trying to get the smoothest possible profile from source to mouth. However,

most rivers find it impossible to reach this smooth profile because of the differences in the

resistance (hardness) of the rocks over which they pass.

By looking at each stage we can see how and why the river changes itself and the shape of

its valley at the different stages along its course. The rivers course may be divided into

THREE main stages.


Upper Stage

The Upper Stage is high up in the mountains

The valley is V-SHAPED. This means it has steep sides.

EROSION and TRANSPORTATION are happening a lot because of the fast flowing water.

DEPOSITION does not have an opportunity yet.

Erosion is cutting downwards. We say it’s eroding VERTICALLY.

The water is shallow but fast flowing.

The river is narrow

There is a lot of friction between the surface of water and the river bed which causes

lots of white water / RAPIDS.

The river winds its way around hard bits of rock called INTERLOCKING SPURS.

WATERFALLS and GORGES are common features in the upper stage.

Middle Stage

The river is slowing down.

The valley is much wider and flatter. We say the valley is U-SHAPED.

The river is much deeper and wider as more tributaries have joined by this stage.

Being flat the valley floor also acts as a FLOOD PLAIN

MEANDERS are a common feature in the middle stage.

EROSION and TRANSPORTATION is common. The DEPOSITION of larger material also

starts happening.

LATERAL EROSION replaces vertical erosion. The river is pushing out sideways not

downwards. This is why the river meanders across the flood plain.

Lower Stage

The river is now very slow moving.

The river is very wide. At this stage the river contains all the water from the drainage

basin

There are no valley sides. The valley is saucer shaped. Each side of the river there is a

wide FLOOD PLAIN.

There is little EROSION.

TRANSPORTATION of only light material eg. sand and silt

Lots of DEPOSITION due to the lack of energy in the river.

Due to large quantities of deposition the river may get choked. If this happens the river

spreads out to form many channels – see later.

When the river floods onto the open land each side of the river a layer of ALLUVIUM

gets deposited by the river. This looks like mud but in fact it makes the land fertile

and excellent for farming.


River Valley Long Profile

The long profile of a river is a cross section from its source to its mouth. Along its profile

the river travels through the upper, middle and lower stages.

The river gradient decreases gradually downstream. It is steep in the upper stage, gentle

in the middle stage and very gentle in the lower stage.

Waves

When we are looking at erosion, transportation and deposition at work in coastal areas we

firstly have to understand what the main tool is that causes these processes.

Waves are instrumental in shaping the coastline and in turn make coastal areas exciting yet

dangerous places to be. The coast is important to us in the United Kingdom as we are

surrounded by 8000km of coastline, none of which is ever far away from us.


What causes waves?

Waves are formed by the WIND dragging on the surface of the water. The area of water,

which the wind blows over, can vary but it is always called the FETCH.

When waves reach the coast

Out at sea waves role along. In strong winds they can be as much as 40 metres high. In lighter winds they may appear like ripples on a glass like surface.

Once the waves reaches the coastline they will break, usually in shallow water. Water then rushes up the beach. We call this the SWASH.

Once the wave loses momentum it rolls back to the sea. We call this the BACKWASH.

If the backwash has more energy than the swash the waves eat away at the land – pebbles

and sand are dragged back into the sea.

BUT

If the swash has more energy than the backwash, material is carried on to the land and is

left there.


Waves at work Waves have energy. That means that they can work. They work non-stop, night and day,

shaping the coastline.

What do waves do? Waves do exactly the same as rivers

They ERODE the coast

They TRANSPORT the eroded material

They DEPOSIT their load in sheltered areas where energy is lost

What causes waves?


How rivers and seas shape the land?

Rivers and Seas work very hard and continually erode and move material. They are a major

force in shaping and altering the land. What happens is that the water pushes along

boulders, stones and rock particles. As it does this so the loose material scrapes the river

bed and banks or the coastline and loosens other material. We call this EROSION. Much of

what is worn away is then TRANSPORTED by the river or waves in the sea and put down

somewhere else. In this way both rivers and seas change the landscape. Rivers by wearing

out and deepening valleys and seas by battering against coastlines. They can also change

their shape by DEPOSITING material.

There are FOUR main processes by which rivers and seas can cause erosion and FOUR

processes by which they transport material.

Erosion

Processes of river erosion

1) ATTRITION

Material is moved along the bed of a river, collides with other material, and breaks up into

smaller pieces.

2) CORRASION/ABRASION

Fine material rubs against the river bank. The bank is worn away by a sand papering action

called abrasion, and collapses.

3) CORROSION

Rocks forming the banks and bed of a river are dissolved by acids in the water.

4) HYDROLIC ACTION

The sheer force of water hitting the banks of the river.


The processes of wave erosion are identical to river erosion.

Processess of wave erosion

1. ATTRITION – chunks of rock knock into each other and wear themselves down into

smaller bits. They end up as shingle / pebbles and sand.

2. CORRASION / ABRASION – sandpapering action caused by the waves throwing sand,

pebbles and stones against the rock.

3.CORROSION – the water is dissolving soluble material from the rock.

4.HYDROLIC ACTION – under pressure water is forced into cracks in the rock. Over time this

eventually breaks the rock down.

The weaker rocks such as clay are eroded quicker than stronger rocks such as granite or

limestone.

The more energy rivers or waves have, and the softer the rock, the faster erosion will be.

Most erosion occurs when a river is in flood or the sea is experiencing stormy conditions. It

can then carry huge amounts of material in suspension as well as being able to move the

largest of boulders lying on its bed.

As a result of erosion a number of different landforms are produced. We are going to look at

:

Waterfalls and Meanders (Rivers) and

Notches, Caves, Arches, Stacks and Stumps on a headland (coasts).

Waterfalls

Waterfalls are common features of a rivers upper stage. A waterfall is caused when there is

a difference in the height of the land over which a river flows. There are many reasons why

there is a height difference but one of the most common causes of waterfalls is a river

flowing over rock types of different resistance (strength).


The land over which the river flows is a complex mixture of different rock types. We have

already seen when we looked at weathering that softer rocks such as sandstone are going to be

worn away much quicker than harder more resistant rocks such as granite.

When a river flows through the upper stage it has lots of energy to erode vertically downwards.

When it flows over an area where soft and hard rock meet common sense tells us that the

softer rock is going to be eroded much quicker. Due to different speeds of erosion a smaller

step will develop and in time this will further develop into a larger step. In front of the step

RAPIDS quite often can be seen and these will cause the water to froth. We call this white

water. Eventually the step will become significantly big enough for the water to fall onto the

lower level of softer rock.

Stage 4

The flow of water falling onto the lower level of softer rock will scrape out a bowl called a

PLUNGE POOL. Hydraulic action is the main force of erosion at work here, but sometimes if the

flowing water has lots of material being carried in it we will also see corrasion.

Stage 5

The bigger the step becomes, the bigger the drop the water has to fall so more spray will be

created when it hits the plunge pool beneath. The spray will hit the softer rock at the back of

the waterfall and this will lead to its break down by chemical weathering.

Waterfalls are best understood if we look at their formation in stages.

Stages 1, 2 and 3


Stage 6

As the back wall moves back due to chemical weathering the layer of harder rock sitting above

it will overhang the waterfall. The more the softer rock moves back the more the hard rock will

stick out. In time, gravity will mean that the overhanging rock will collapse and fall into the

plunge pool.

Stage 7

After the overhanging rock has collapsed the river water will then fall slightly nearer to the

source and cause the whole waterfall to retreat upstream, leaving behind it a very steep sided

valley called a GORGE.

Meanders

Ideally a river would like to flow from source to sea in a straight line. This however, is not

possible as a river is forced to turn. We call a turn in a river a MEANDER.

Meanders will start to form when an obstacle blocks its path/course. This obstacle is usually

hard rock.

Once the river starts to turn LATERAL EROSION will make the bend get larger. The outside

bend will be forced outwards because of erosion and the inside will build up with deposition

and follow it.


Outside Bend

As a river goes around a bend most of the water is pushed towards the outside causing

increased erosion. The bank becomes very steep and may even be undercut. Water is faster

and so lateral erosion takes place. The river here is deeper and RIVER CLIFFS may be seen.

Inside Bend

On the inside of the bend, in contrast, there is much less water. The river will therefore be

shallow and slow flowing. It cannot carry as much material and so sand and shingle will be

deposited. The deposited material collects at the bottom of the SLIP-OFF-SLOPE.


Inside Bend

On the inside of the bend, in contrast, there is much less water. The river will therefore be

shallow and slow flowing. It cannot carry as much material and so sand and shingle will be

deposited. The deposited material collects at the bottom of the SLIP-OFF-SLOPE.


Features formed as a result of coastal erosion:

wave cut notches

caves

arches

stacks

stumps

All the above features develop in sequence over a long period of time and are seen on many

headlands around the world. Some of the most famous being:

‘The Green Bridge of Wales’ on the Pembrokeshire Coastline in West Wales.

Durdle Door in Dorset

‘London Bridge’ in the state of Victoria Australia.

Azure Window Malta – an arch which collapsed on the 8th March 2017. In collapsing the power of the sea did not even leave a stack or stump as we would expect but instead, everything was removed.

The ‘Needles’ in the Isle of Wight and ‘Old Harry’s Rock’ are other examples too.


Transportation

Transportation involves the movement of material which has been eroded.

Moving water in rivers and along the coast can do this in one of four ways.

Processes of river and wave transportation

1) TRACTION

Large rocks and boulders are rolled along the river / sea bed.

2) SALTATION

Smaller stones are bounced along the river / sea bed in a leap frogging - motion.

3) SUSPENSION

Fine material, light enough in weight to be carried by the water. It is this material which

discolours the water.

4) SOLUTION

Dissolved material transported in the water. This material also discolours water.

The process of transportation does not actually produce features that we can see as the

process always involves the movement of material. Material therefore, is not in one place

for long enough to form a feature. Instead we have to look for evidence that the process is

working.

In a river we have already seen that on a meander bend for erosion on the outside to

happen and deposition on the inside, transportation must be the link!

Along the coastline we are going to look at the process of ‘Longshore Drift’ which we can see the full force of by looking at the work done by groynes to try and slow it down.


Coastal Groynes

As a way of reducing Longshore Drift and stopping beaches being carried away many seaside

resorts build GROYNES. These are basically walls which are built at right angles to the sea

(down the beach). Their job is to trap sand. The bigger the problem of longshore drift the

closer the groynes are to each other.

Direction of longshore drift


Wave coming onto

beach at an angle

A close up of

a groyne


Deposition

As a river slows down or the sea is experiencing calm conditions it will start to drop or

deposit the material which it has picked up. The largest particles are dropped first and the

finer material such as sand and silt are deposited last of all where the river is flowing very

slowly or the sea has lost its energy. As a result of Deposition a number of different

landforms are produced.

Estuaries and Deltas in a river

Beaches and Spits along the coastline.

Estuaries

At the lower stage, at the mouth the river is very slow flowing. The result of this is that the

river only has the power to deposit. The deposited material however, is never given any

time to settle as the tide comes in and out twice a day. The power of the tide will constantly

move the material deposited by the river. This area of the river will expose sand banks/mud

flats at low tide and we call it the ESTUARY.

It is important to remember that because the deposition is never allowed to settle, an

estuary is not a feature of deposition. We need to understand what an estuary is so that

we know what a delta is. (A delta is a feature of deposition).


Deltas

If a river flows into a sea which has a weak tide or no tide at all their will not be an injection

of fast moving water on an incoming tide, so the material deposited by the river will get the

opportunity to build up. When this happens the river becomes shallower. The shallower it

gets the more chance salt water tolerant plants will grow on the deposited material.

Because the river has little power it struggles to get through the deposited material. The

water then breaks into smaller channels called DISTRIBUTARIES or BRAIDED CHANNELS.

These are basically narrow channels of river water finding weak areas in the deposited

material. We call this area a DELTA.


Spits

Beaches

Beaches are made up of sand, mud, pebbles or shingle, usually from the material that has

been eroded from the headlands and cliffs. Usually this material has been eroded from

rocks nearby but it may also come from miles away, caught up in the action of the waves

and longshore drift.

Beaches are important because they protect the coastline from wave attack. If you visit a

beach on holiday you will see little change in it whilst you are there. However, the constant

action of waves breaking on the beach particularly during a storm can lead to beaches

changing in appearance at different times of the year.

Beaches grow in sheltered areas because calm, slow moving water deposits material which

helps build a beach. (see diagram A)

On straight stretches of coastline we may have to work harder to keep the beach in one

place. This will depend on the impact of longshore drift.


How can the risk of flooding be reduced?

The reasons for trying to reduce the risk of floods may depend upon several factors: Places which flood frequently are more in need than places which only flood occasionally. Small floods may be a nuisance which have to be endured. Perhaps nothing can stop very big floods. Attempts to stop floods will be greater where lives and poverty of many people are at risk. The methods used will depend upon the wealth of the country e.g. poor countries like Bangladesh cannot expensive dams like those in the USA. Methods by man to reduce flooding:

Dams and reservoirs The construction of dams creates reservoirs, which apart from preventing flooding provide water supply and hydro-electricity. Dams hold back water at times of flood and release it when river levels are lower.

Aforestation The planting of trees delays run-off and reduces the amount of water reaching the river. Diversionary spillways These are overflow channels, which can take surplus water during times of flood. The water is usually diverted into small bays, reservoirs and lakes and eventually into the sea.

Strengthening levees Levees used to consist of soil, which was vulnerable to erosion. Today levees are made of concrete. The levees are positioned to cover the deepest part of the river to above the flood level.

Making the course straighter and shorter This method aims to get rid of floodwater from the river basin as quickly as possible. It is achived by cutting through narrow necks of large meanders. By shortening the distance of the river so the speed of the river increases.


B- Glossary


GLOSSARY OF USEFUL TERMS

A

abrasion: a type of erosion involving rock particles being scraped against, and

wearing away, the surface of other rocks.

active: a volcano which is constantly or frequently erupting

air: mass a very large body of air with relatively uniform temperature and moisture

characteristics

air pressure: the weight of the air above a reference point, measured in millibars

anticyclone: an area of high air pressure bringing clear skies

arch: a coastal feature created by the erosion of back to back caves

atmosphere: the layer of air round the earth

attrition : a type of erosion involving rock fragments being ground together to

become smaller, smoother and rounder

B backwash: the outgoing water from a coastal wave

bay: an area of sea between two headlands beach material which the sea deposits on the

coast

biodiversity: the number and variety of all living things within an ecosystem

birth rate: the number of babies born per thousand of the population per year

braiding: a river feature consisting of islands of sediment deposited in the river

channel in its middle course

BRIC countries: countries with rapidly expanding economies: Brazil, Russia, India, China,

South Africa

brownfield site : disused or derelict urban land which is available for redevelopment

business park: a development of offices and industrial units

bypass: a road built round a town

C

CBD: Central Business District: the commercial and business centre of a town or city,with

highest land values

climate : the average weather over many years

collision: boundary where continental plates collide, forming mountain chains

compass: an instrument used to identify direction

condense: gas becoming liquid

confluence : the point where two rivers (including tributaries) meet

conservative boundary: where two tectonic plates slide past each other, but where crust is


neither formed nor destroyed

conserve: not to waste resources

constructive boundary: where two tectonic plates move apart from each other and new

crust is formed

containerisation : to transport goods in standard-sized, sealed containers

continent : a large land mass (a total of seven)

contour line : a line on an OS map joining all points of the same height

convection current : heated plumes of magma which create crustal plate movement

convectional rain : rain formed by the sun heating the land surface causing moist air to rise,

condense and produce heavy rainfall

core: the centre of the Earth

corrosion : a chemical process involving the dissolving away of sedimentary rocks, e.g. chalk,

limestone a type of erosion by water involving the dissolving away of rock, particularly

limestone and chalk

crust : the thin outer layer of solid rock round the Earth’s surface

D death rate: the number of deaths per thousand of the population per year

delta : a depositional landform created where a river splits into numerous outlets

depression : a cyclonic weather system bringing precipitation and winds

desert : an area receiving less than 250 mm of precipitation per year

destructive boundary : where an oceanic plate slides underneath a continental plate or

another oceanic plate

detached : a house which is completely separate from other houses

dispersed : spread out

distribution : the spread of places, people or data

dormant : inactive

drainage basin : an area of land which is drained by a single river and its tributaries

drought : a prolonged period of below average precipitation

E earthquake : a sudden and violent shaking of the ground caused by tectonic

movements

easting : a vertical grid line on an OS map

ecosystem : an area displaying a distinctive interaction between plants, animals and the

physical environment

eco-tourism : low impact tourism aimed at protecting the natural environment and local

cultures

environment : the air, land, water, plants and wildlife


epicentre : the point on the Earth’s surface directly above the focus of an earthquake

Equator : the imaginary line running round the middle of the Earth

erosion : the wearing away of land by material carried in rivers, glaciers, waves and wind

estuary: the final section of a river, subject to tides

ethnic group : people of the same cultural background

evaporate : liquid turning to gas

exploit : to seek and to use a natural resource for human benefit

extinct : no longer in existence (of animals); no longer active (of volcanoes)

F fault : a line of weakness in rock

fetch : the maximum distance over which wind can blow to form a wave

fieldwork : an enquiry which takes place outside the classroom

floodplain : the flat area either side of a river which is regularly flooded

focus : the point underground where the rock breaks and the energy of an

earthquake is released

fog : cloud at ground level (reducing visibility to less than 1km)

front : the boundary between warm and cool air masses

frontal rainfall : rain formed when warm, moist air rises over cold air, causing

condensation and precipitation

function : the activities of a settlement

G

geothermal energy : heat and electricity produced from hot, underground water

gorge: a deep, steep-sided valley

greenfield site : land which has not previously been built on

grid reference : a number which locates an area on a map

globalisation : the ways in which companies, ideas and lifestyles spread round the world and

interact with one another

H habitat : an area in which plants and animals have adapted in order to survive there

headland : a promontory of resistant rock which juts out into the sea

hemisphere : half of the globe

hierarchy : a ranking of settlements according to their size, functions or importance

high order settlement : a settlement which contains top- level shops and services

HS2 : High Speed Railway 2 - a planned high-speed railway proposed to run between London


(Euston) and the Midlands and the North of England

humidity : the moisture in the air

hydro-electric power : electricity produced by water being released through dam turbines

hydraulic action : a process of erosion involving water and air trapped in cracks and crevices

I

igneous : a type of rock/process/landform involving magma

impermeable : not allowing water to pass through

infiltration : the movement of water from surface into the soil

interception : precipitation landing on plants, trees or buildings

interlocking spurs : a series of alternating rocky projections found in mountain river valleys

irrigation : the artificial watering of crops

isotherm : a line on a map joining points of equal temperature

J jet stream : a fast-flowing, narrow air current found in the atmosphere

joint : a crack in bedrock

K

key : a list giving the meaning of symbols on a map

L

lahar: a product of volcanic eruptions, composed of a mixture of ash and

water

land use : the way in which land is put to use by humans

landfill : the disposal of waste in natural or man-made holes in the ground

lava : molten rock at the Earth’s surface

LEDC : Less Economically Developed Country

levée : an embankment next to a river channel, raised above the flood plain

life expectancy: the average age which men and women may expect to reach

in a particular country

linear : extending in a line

longshore drift : the movement of sand and pebbles along a beach by wave

action

low order settlement : a settlement which contains few basic shops and


services

lower course : the stage of a river as it nears the sea, dominated by the process

of deposition

M

magma : molten rock beneath the Earth’s crust

mantle : the semi-solid mass of rock beneath the Earth’s crust

market : the place/point where goods and services are sold

meander : a bend in a river found in its middle and lower courses

metamorphic : a rock that has undergone transformation by heat and/or pressure

MEDC: More Economically Developed Country

microclimate: the local climate of a small area e.g. a garden

middle course : the stage of a river between its upper and lower sections, containing a

mixture of erosion and deposition

migration : the movement of people from one place to another

mouth: the point where a river enters a sea, ocean or lake

multinational : a company which operates in several different countries

N national park : an area of countryside of outstanding beauty which is protected from

development

natural increase : a rise in population caused by a greater number of births than deaths

NIC : Newly Industrialised Country

North Atlantic Drift : an ocean current which warms coastal areas in western Europe

northing : a horizontal grid line on an OS map

nucleated : clustered together

O oxbow lake : the cut-off remnant of a meander found in the lower course of a river

OS : Ordnance Survey

P permeable : allowing water to flow through, e.g. joints in rocks

plate boundary : the point where two tectonic plates meet

plate tectonics : the theory explaining how the Earth’s crust is able to move


plunge pool : a deep pool which is formed by erosion at the base of a waterfall

pollution : damage to the environment as a result of human activity

porous : able to hold water like a sponge, allowing it to flow through

precipitation: rain, snow, hail or sleet

prevailing wind : the most common direction of wind e.g. SW in the British Isles

primary industry : an economic activity involving the collecting of food and raw

materials from the Earth

primary data : information gathered in person through fieldwork

pull factors : reasons why migrants are attracted to a destination

push factors: reasons why migrants leave their homes to go elsewhere

pyroclastic flow : a cloud of superheated gas and ash ejected from a volcano

Q quaternary industry : a high-tech industry involving research and manufacturing, employing

highly- skilled workers, e.g. computer chips, pharmaceuticals

R

rapids: fast-flowing, white-water section of the upper course of a river

raw material : mineral and agricultural resources which can be processed to make

something else

recycling : the reuse of waste material

relief : the height and shape of land

relief rainfall : rain formed when moist air is forced to rise over highland, causing cooling,

condensation and precipitation

renewable energy : a sustainable source of power which can be used indefinitely (e.g. wind,

solar, tidal)

reservoir : a lake behind a dam

resource : any product of the environment which can be used for the benefit of

people retail the sale of products to the public

Richter Scale : a logarithmic scale used to measure the magnitude of earthquakes

river basin : an area of land drained by a river and its tributaries

river cliff : a steep, undercut area on the outside of a river meander

routeway : a line of transport, e.g., road, rail, sea or air

run-off : the movement of water across a surface

rural : relating to the countryside

S saltation: the transport of sand in a hopping fashion in water or air


science park : a development of high-tech industries often close to a university

scree : piles of broken rock found beneath steep rock faces

secondary data : information collected by a third party

secondary industry : an economic activity involving the manufacturing of goods

sedimentary rock : layered rock formed by the deposition of sediments

seismic wave : a shock wave produced by earthquakes

seismometer : a sensitive instrument used to measure earthquakes

semi-detached : a house joined on one side to another

service industry: an economic activity such as retail, administration, education,

healthcare or tourism

settlement pattern : the shape and spacing of settlements

settlement : a place where people live

site : the exact location of a settlement

situation : the location of a settlement in relation to the surrounding area (its

environs)

slip-off slope : a gently-sloping area formed on the inside of a river meander

solution : the transport of a soluble load in water

social : relating to society

source : the beginning of a river

spit : an extended beach which grows by deposition across a bay or river mouth

spur: a rocky projection found in the upper stage of a river’s course

spurs : see interlocking spurs

stack : a pillar of rock which stands in the sea

stewardship : looking after resources in a sustainable way for the future

subduction zone : the downward movement of crust at a destructive plate boundary

suburb : the residential and commercial development at the edge of a city

sunrise industry : a newly-developed, growing business sector

sunset industry : a long-established business sector in decline

suspension : the transport of silt in water

sustainable : using resources in a manner which allows them to be available for

future generations

swash : an incoming coastal wave

symbol : an image, letter or number used on a map to indicate a particular landscape

feature

T tectonic plate : a large, rigid section of the Earth’s crust

terraced : a house joined to another on both sides, forming rows

tertiary industry : an economic activity providing a service (as opposed to a product) for


their customers

through flow : the movement of water through the soil as part of the water cycle

tourism : a tertiary economic activity involving the commercial organisation of

holidays and visits to places of interest

traction: the transport of boulders in a rolling motion in water

transpiration : the release of water vapour into the air from plants

transportation : the movement of eroded material

tributary : a river joining a larger river

tsunami : a sea wave caused by earthquakes and volcanic eruptions

U upper course : the section of a river near its source, dominated by the processes of erosion

urban : relating to a town or city

urbanisation : the increase in the percentage of people living in cities

V volcano : a mountainous vent or fissure in the Earth’s crust which emits lava and other

igneous products

volcanic bomb: lava exploded into the air which solidifies as it falls

W waterfall : a point on a river where water falls vertically

watershed : an area of highland separating river basins

water table : the upper surface of water in the ground

weather : the day-to-day condition of the atmosphere

weathering : the breakdown of rocks in situ by mechanical, chemical or biological means

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