geography - physical landscapes Paper 1

yr 11 oct ->

define upland

an area of high or hilly/mountainous land

low land define

an area that is low relative to its surrounding areas

landscape define

an extensive area of land regarded as being visually and physically distinctive

define coast

the boundary between the land and the sea

define swash

when water moves towards the beach

define backwash

when water moves away from the beach

wave formation

waves are caused by the transfer of energy ffrom the wind to the sea due to friction of the wind on the waters surface

the size and energy of a wave is influenced by (3)

• how long the wind has been blowing

• the strength of the wind

• the fetch

define fetch

how far the wave has travelled

types of waves (2)

constructive waves

destructive waves

the difference between constructive and destructive waves

constructive (deposition - makes new land) destructive (erosion - break land down)

-constructive waves have a:

-weaker back wash - beach isnt eroded

-beach IS built up by material brought up in swash vs a weaker swash

-stronger swash

-longer wavelengthes

-shallower waves

-lower frequency

-

whats the top of the wave called

whats the bottom of the wave called

top = crest

bottom = trough

define weathering

the breakdown of rocks by physical actions at the top of the cliff e.g. rain,snow, or cold

difference between weathering and erosion (2)

weathering involves no moment - erosion does

occurs at top of the cliff - erosion occurs at the base of the cliff in association with the sea often

physical weathering

diagram + how it works

where water gets into the cracks in the rock. changes in temp cause the water to freeze. when water freezes it expands and makes the cracks bigger. The ice then melts, this process will repeat many times

chemical weathering

is where chemicals react with the rocks. Oxidation is one type of chemical weathering, it causes rust. Acid rain causes limestone to disintergrate and become weaker. This is when water and carbon mix together

biological weathering

is where vegetation roots grow into cracks in the rock. this then prises the crack to open. this can also happen with animals that burrow into rock (e.g. rabbit). Both of these weaken the rock

define mass movement

the downhill movement of soil and rock on a slope, primarily driven by gravity

what are the different types of mass movement

slides

slumps (most likely to be asked about in exam)

rock falls

mass movement

slides

• material shifts in a straight line along a slide plane

• often occur on cliffs made of resistant rock e.g. sandstone

• ususally triggered by erosion or heavy rainfall

• happens by:

-marrine erosion - forms a wave-cut notch, removing support

-rain water infiltrates the rock adding weight + reducing internal cohesion

mass movement

slides

• material rotates along a curved slip plane

• often occurs when cliffs are made of soft materials e.g. boulder clay

• top looks the same, just dropped slightly

• has 2 different types of material soil + clay

happens by:

-rainwater infiltrates + saturates the clay (weight inc)

-waves erode base of cliff through hydraullic action + abrasion, forming a wave-cut notch

mass movement

rock falls

• material breaks up, often along bedding planes and falls down a slope

• common on steep/verticle clkiffs, composed of hard. jointed rock e.g limestone

happens by:

-weathering processes, esp freeze-thaw, widen joints + cracks in the rock

coastal processes (3)

1. erosion

2. transportation

3. deposition

• same for coasts and rivers

define erosion

the wearing away and removal of material by a moving force such as a breaking wave

types of erosion

hydraulic action

define + picture

this is the force of water hitting the cliff and squeezing air into the cracks in the rock

types of erosion

abrasion

define + picture

the force of the sand and pebbles carried in the water blasting into the cliff

types of erosion

attrition

define + picture

this is the process of rocks hitting each other and breaking into smaller rocks

types of erosion

solution

define + picture

a chemical reaction between the sea water and the minerals

why do some coasts erode more than others (6)

1. large fetch

2. no beach (takes impact of the waves)

3. strong winds (cause destructive waves)

4. cracks in rock (more prone to erosion - is weaker)

5. rock is less resistant (weaker)

6. waves refract and hit the sides

define transportation

the movement of sediment (sand) along a coastal region

types of transportation from biggest → smallest

• traction

• saltation

• suspension

• solution

transportation

traction

define + picture

pebbles and larger sediment are rolled along the sea bed

transportation

saltation

define + picture

load is bounced along the sea bed e.g. small piceces of shingle or large sand grains. Currents cannot keep the larger and heavier sediment afloat for long periods

transportation

suspension

define + picture

small particles are carried in the water e.g. silts and clays which can make the water look cloudy. Currents pick up large amounts of sediment in suspension during a storm, when strong winds generate high energy waves

transportation

solution

define + picture

minerals are dissolved in sea water and carried in solution. load is not visible. load can come from cliffs made from chalk or limestone, and calcium carbonate is carried along in solution

longshore drift diagram

define deposition

the ‘dropping off’ of sediment →has to have sand for deposition

do waves have high or low energy

low

define bay

acresent shaped indentation in the coastline between two headlands - made of softer (less resistant) rock that erodes quicker

define headland

a cliff that juts out into the sea - and so is surrounded by water on all 3 sides - made of harder rock that erodes slower

discordant coastline

the different types of geology run at right angles to the coast

define concordant coastline

the different types of geology run at parallel to the coast

how are headlands and bays formed

when more and less resistant rock lie next to each other on a discordant coastline. the waves pound against the rock and erode it away. The soft clay will erode more quickly forming a bay whereas the hard chalk will erode more slowly, causing a headland to form

headland formation - errosional land form - formation of caves, arches and stacks

1. a large crack is enlarged by the pressuure on/off effect of hydraulic action

2. the crack grows into a notch and then a cave as destructive waves converge on the headland and continue to erode it

3. overtime, the cave becomes larger, wavere fraction draws waves to all sides of the headland so caves may form back to back

4. the sea breakes through the back of the caves forming a natural arch. the base of the arch is widened as notches form from hydraulic action + abrasion

5. weathering è.g freeze thaw continues to weaken the top of the arch, making it less stable

6. the top of the arch eventually collapses

7. this leaves a pillar of detached rock called a stack

8. notches at the base of the stack which eventually makes it unstable

9. the stack will eventually topple into the sea leaving only its base this stump is normally only visible at low tide

cliff characteristics

• the shape of cliffs depend on the rate at which they erode

• the rate at which a cliff recedes depends on the resistance (hardness) of the rocks

-e.g.- more resistant (hard) granite cliffs at Lands end (cornwall) retreat at a 0.001 metre annually and will be really tall and steep

• soft boulder clay at happisburgh (norfolk) have a 5 metre anual rate of

cliff retreat and wave cut platform diagram and formation

1. marine erosion (hydraulic action) undercuts and erodes the base between the high tide and the low tide

2. over time at wave-cut notch is formed from the constant erosion at the base of the cliff

3. an overhang is visible over the top of the wave-cut notch

4. weathering e.g. freeze thaw attacks the overhang making it weaker and more vulnerable and the wavect notch is enlarged due to erosion

5. the wavecut notch is enlarged further that the overhang starts to collapse on the beach below. a steep cliff is now created

6. the process repeats and cliff continues to retreat. the old base of the cliff is left as wave-cut-platform

characteristics of a wave cut platform

• smooth bare rock

• deep cracks

• barnacles clinging to the rock (seaweed thrown through rough seas)

• low tide

• gentle slopes

• covered at high tide and exposed at low tide

• pitted appearence (bare rock with rock pools)

define depositional

sand being ‘dropped off’

define beach

a landform of coastal deposition that lies between high tide and low tide levels

beach profile DIAGRAM

a)dunes or storm beach

b) backshore(not usually affected by waves so usually dry)

c) foreshore (inter-tidal zone that is repeatedly covered then uncovered by changing tides

d) near shore (where waves break)

e) offshore (waves not breaking)

sand dunes

where do they start

what is deposited on the beach + where

name of first sand dune formed

word describes what the plants will do to the embryo sand dune over time

what example is given of a pioneer species

what happens to the embryo dune over time/what does it turn into

what has happened for this second dune to form

what has also formed in front

what will happen to the embryo dune

what other examples of pioneer species are there

what will make the sand dunes stable

how lonng does this process take

1. where there is lots of sand

2. seaweed - or some other kind of barrier thats holding the sand back

3. embryo dune

4. colonise

5. marram grass

6. gets bigger and becomes more stable

7. has been stabilised

8. another sand dune

9. it will become more stabilised and another will form in front

10. sea lime and sand sage - has to be plants that can withstand wind + salty water

11. vegetatio

12. up to 400 years

how sand dunes change in land DIAGRAMS

define spit

a sand or shingle beach that is joined to the land but projects into the sea (like a finger)

features of a spit

1. prevailing wind direction

2. direction of longshore drift

3. salt marsh and mudflats develop

4. original coastline

5. strong river current stops spits extending further

6. secondary wind causes end of spit to curve

7. river mouth or estuary

how are spits formed

spits are formed where the shape of the land changes direction. The prevailing wind causes long shore drift . Swash of the waves will come in at an angle and the backwash will go back at 90 degrees. This means the sand is transported along the coast and deposited in the sea. This makes the spit which will have a curved end

e.g. Sandbanks spit, in poole, dorset isn’t growing due to tidal currents and dredging

define bar

a ridge of sand or shingle that stretches from one side of a bay to the other, forming a lagoon behind it

lagoon is a lake but with sea water - part of the ocean (lakes are fresh water

how are bars formed

hard engineering define

builing strong barriers with concrete steel and or rocks. The main aim is to stop the waves eroding the coast. Man made. Materials are more expensive and last longer

soft engineering define

methods aim to work more in harmony with nature than the large man made hard engineering structures. Is still man made. Cheaper but doesnt last as long

e.g. adding more sand to the beach

coastal management - soft engineering

beach nourishment

description, picture, advantage, disadvantage, cost

replaces sand and shingle, which has been lost from the beach. absorbs energy and is good defence against the sea. It protects land or sea wall behind the beach and looks more natural

• looks natural and can provide people with an area for recreation as people can play on the new formed beach

• less expensive than most hard engineering methods

-needs to be done regularly as beach is washed away

-hard to find same type of sand/shingle as before

cost=£2 mill per km

coastal management - soft engineering

dune regeneration

description, picture, advantage, disadvantage,cost

artificially creating new sand dunes along the coastline to act asa buffer between the land and the sea. Sand dunes are under threat because they are fragile and people walk all over them and destroy the dune ecosystem

• relatively low cost and provides a natural appearance with limited visual impact. Helps to maintain the ecosystem

-need regular maintanence, they are less likely to be effective against extreme storm events

-less time consuming to plant marram grass + fence off areas

cost=£2000 per 100m

coastal management - soft engineering

managed retreat

description, picture, advantage, disadvantage,cost

areas of coast are allowed to erode and flood naturally. ususally this will be areas considered to be of low value

• encorages the development of beaches (natural defense) and salt marshes (important for environment)

• low cost

-is low cost but not be free as ppl will need to be compensated for loss of buildings and farmland

cost=depends on stretch of coastline that is letting erode. Undeveloped coastline will be cheaper than developed stretch of coastline

coastal management - soft engineering

marsh creation

description, picture, advantage, disadvantage,cost

allowing the sea to flood and spread over a large area - creating a salt marsh

• new habitats are created

• reduses risk of flooding along the coast

• low cost

-ppl/ businesses may need to move away from land that is going to be flooded

-value of land will be lost

coastal management - hard engineering

groynes

description, picture, advantage, disadvantage,cost

built down the beach and into the sea about 200m apart. They slow the movement of material along the coast and help build up the beach

• stops the transport of material away from the area you are trying to protect which leads to a beach then helps to protect the land

-may cause erosion on other areas of the coastline as there is no longer a beach there to protect it

-costly to build and maintain

-ugly

cost = £1.5 mil each region

coastal management - hard engineering

sea wall

description, picture, advantage, disadvantage,cost

stops waves reaching the land. they reflect the waves back to the sea, but this can wash away the beach. They give good protection but are expensive and may need to be repaired in time

• protects base of cliff from erosion and can prevent coastal flooding of the same area. the land and buildings around the cliff are protected from erosion

-sea walls are very expensive to build and they need regular maintanance (expensive)

-sea walls often reflect back into the seawhhich leads to inc erosion of the beach

cost=£7mil per km on av

coastal management - hard engineering

rock armour / riprap

description, picture, advantage, disadvantage,cost

mixture of large boulders and concrete blockas which protect the coast by breaking up the waves

• helps retain the beach. they absorb the wave enrgy so the waves no longer have the enrgy to erode the cliff or beach

-dont protect the cliffs as much as other types of coastal protection

-initial cost of transporting the boulder and concrete blocks is large

cost=£3mill per km on av

coastal management - hard engineering

gabions

description, picture, advantage, disadvantage,cost

a cage, cylinder or box filled with rocks, concrete or sometimes sand and soil for use in civil engineering, road building, military applications and landscaping. for erosion control, caged riprap is used

• relatively cheap

• quick solution

• last 20-25 years

-can only be used on sandy beaches

-easy worn away - need to be maintained - can be dangerous if they are damaged

-can be unsightly

-birds can get their feet caught in them

cost=£110 per metre

coastal realignment define

allowing area to flood and erode so habitats can thrive and through natural processes the shoreline is reshaped. This is a type of soft engineering that is very sustainable and long term