GEOGRAPHY YEAR 10

part 1 and 2 of coast

Weathering and what type of process is it?

• Happens outside the water when rock is broken down by natural processes from the Earth

• (ie, rainfall, temperature or chemical reactions)

• in situ (at one place)

• and its a sub ariel process

erosion and what type of process?

• when rock is broken down by the force of water

• its a marine process. This continuos action helps shape coast lines

name four different types of erosion

• attrition, -

• abrasion,

• solution

• and hydraulicaction

attrition

• material (mainly rocks) carried by waves gets rounder and smoother

• this is because it collides with other rocks/ materials causing sharp edges to get knoched off

abrasion

• waves throw stones and rocks at cliffs

• rocks scrape against the cliff wearing it away

• rocks keep rubbing against cliff over time until it’s loose therefore eventually eroding

solution

• chemical reaction its when salt water reacts with different rocks

• chemical reaction between them causes rocks to slowly erode and disslove

hydraulic action

• waves crash against cliffs at high forces

• over time waves force air pockets into the cracks in the rocks

• the air then expands causing cracks to widen and loosen

where would erosion be higher

• large fetch (so long fetch allows waves to grow in height and strength, making them more destructive to the coastline because they generate more force)

• softer rock (really weak so it erodes wuite quickly)

• area with a lot of destructive waves (because strong the backwashes leads to erosion)

• rocks with more gaps (hydraulic action)

name 3 main different types of weathering (sub Ariel processes)

• freeze thaw

• chemical

• biological

what is mechanical weathering give examples

• Mechanical weathering (also called physical weathering)

• is the breakdown of rocks into smaller pieces without any chemical change.

• The rock’s minerals stay the same, only the size and shape change. examples are feeze thaw and exfoliation

freeze thaw weathering when does it occus and how

• occurs when rocks are porous (contain holes) or are permable (allows water to pass through)

• water first enters cracks in the rock

• temperature drops below 0 degrees celcius and the water turns into ice. It expands by freezing and begins to push the rock apart

• then when temperature rises the ice in the crack will melt so the water makes it way deeper into the crack

• process repeats until rock splits entirely

biological weathering + how could it be chemical

• weathering cause by plants and animals

• animals might burrow into cracks and plants might grow their roots within

• so as burrow or roots grows the crack becomes larger causing small pieces of rocks to break away

• (or lichens and mosses release chemicals that dissolve the rock)

chemical weathering

• rainwater and sea waters are weak acids

• so because of them coastlines made of limestone or chalk dissolves in water over time

• (another examples is carbonation its when weak carbonic acids attack rocks)

exfoliation

• common in hot climates aka onion skin weathering

• surface layers of the rock are heated so it expands during day

• at night the outer layer cools down and contracts more than rest of the rock

• cracks will form and rocks start to peel away like an onion

what is meant by permability and what are impermable rocks

• the permability of a rockk defines hiw vulnerable a rock is to erosion

• Impermable rocks are less vulnerable as water is not absobed into the rock

what does igneous and sedimentry mean

• igneous is the strongest rock therefore it erodes slowly

• sedimentry is the weakest rock so it erodes really quickly

what is mass movement

• the shifting of loose material downa slope

how does mass movement happen and what does it cause

• Weathering weakens coastal rocks.

• Gravity causes them to collapse (mass movement).

• Material falls to the sea and is eroded by waves.

how are waves created 

• Waves are caused when the wind blows over the sea transferring some of its energy. 

• Friction with the sea water causes ripples to form and these develop into waves as they reach the coast.

what does a fetch do and what is it

• a fetch determines the height if a wave

• a fetch is how far and how long wind has been blowing over the sea

what is long shore drift and how does it work

• long shore drift is the movement along the shore by wave action. It haooens when waves aproach the beack at an angle due to prevailing winds

• the swash (waves moving up the beach) carries material up along the coast line

• the backswash (waves moving back down the beach) carries material back down the beach at right angle 

• once the waves loose energy material is deposited further down the bay to form a beach

what type of weathering caused this

• mechanical weathering (freeze thaw) this is possible due to low temperature

what type of weathering caused this and why

• chemical weather the holes seen are formed due to rain (which is slightly acidic) -

• so when the acid reacts with certain minerals dissolved the parts of rocks 

• so over a long period pits and holes such as the one you see are formed

what type of weathering is seen

• biological weathering 

• the trees is seen growing in the cracks of the rock which will eventually erode it

3 main things waves do

• they wear away or erode coasts

• carry and transport eroded material

• they drop or deposite it in sheltered areas when they loose energy 

• so waves shape the coastline by eroding transporting and depositing material

what’s traction, saltation and suspension

• traction is when rocks roll aong the sea bed

• saltation is when rocks bounce along the sea bed

• suspension is when rocks are carried by  the water

7 features of destructive waves

• height- is high (more than 1m)

• length- short

• Frequency - more than ten a minute

• energy- high

• beach gradient- steep

• main process- erosion

• strong back wash but weakerswash

7 features of constructive waves

• height- is low (less than 1m)

• length- long

• Frequency - fewer than ten a minute

• energy- low

• beach gradient- flat

• main process- depostion

• strong swash but weaker back wash

Long shore drift

• LSD is the movement along the shore by wave action. It happens when waves approach the beach at an angle due to prevailing winds

• The swash (waves moving up the beach) carries material along the beach

• The backswash (waves moving back down the beach) carries material back down the beach at a right angle

• Once the wave looses energy it drops the material further along the bay to form a beach

What’s a bay

• An area of soft (less resistant rocks) which has been worn away more than the headland

• usually a sandy beach

What are headlands

• Are hard more resistant rocks which are left sticking out the sea

• Often known as cliffs

Formation of head lands and bays

• Discordant beds of sediment face wave attacks from destructive waves

• Destructive waves causes hydraulic action (so the waves come at high forces forcing air pockets into the cracks of rocks eventually causing the cracks to widen and loosen ) and abrasion (meaning the destructive waves throw stones and rocks at cliff causing the rock to wear away this causes the rocks to rub against cliff and until it’s loose and eroded)

• So the less resistant rocks are eroded at a faster pace to create bays and the more resistant rocks stick out to form headlands (known as differential erosion)

• During calm periods material is deposited to form a beach

Formation of cliff retreat

• Sub Ariel process weathering (explain) weakens the top of the cliff

• The sea attacks the base of the cliff due to marine processes called hydraulic action (explain) forming a wave cut notch

• The notch increases in size causing the cliff to collapse due to gravity

• The backwash carries rubble toward the sea forming a wave cut platform

• This process repeats causing cliff to retreat even more

Put these in orders stack, stump, cave and arch

• Cave

• Arch

• Stack

• Stump

Formation of caves arches stacks and stumps

• Destructive waves attack the line of weakness on the headland and erode it through abrasion and hydraulic action (explain)

• As erosion continues the cracks are widened and deepened to form a cave

• Eventually over time, erosion continues and will erode all the way through to form an arch

• Freeze thaw weathering (explain) weakens the roof of the arch. Eventually it’s weakened so much to the point where it collapses due to gravity forming a stack

• The bottom of the stack is eroded through wave action. This makes it unstable and the top of the cliff collapses to form a stump

Label the numbers

• Cave

• Arch

• Stack

• Stump

Features of sandy beaches

• Sheltered where there is lower energy waves

• Created by constructive waves with a stronger swash

• Has flat/ shallow beach

Features of pebble beach

• Exposed beaches which have a large fetch

• Created by destructive waves with stronger backwash

• Has deep/steep beach

Formation of a spit

• A spit happens due to longshore drift (explain) so LSD brings material further down the coast.

• Then waves loose energy causing material to deposit over shallow waters. As deposition continues over a long period of time, a long ridge of sand starts to form on top of the shallow water

• The shape of a spit can look like a hook due to prevailing winds changing direction this causes material to deposit in a different direction

• The spit seals off the estuary and the material which is deposited behind the spit provides a slit for the sal marsh to form

Formation of a bar

• Bars form the same way as a spit initially (EXPLAIN) but bars are created where a spit grows across a bay joining two headlands

• Behind the bar a lagoon is created where water has been trapped

• However is some cases the lagoon may gradually be in filled (accumulates with sediment) as a slate marsh develops due to it being a low energy zone encouraging deposition

Formation of tombolo

• Are formed a spit continues to grow by LSD (explain)

• Joining land to an offshore island

Label what’s going on

• 1 direction of longshore drift

• 2 prevailing wind direction

• 3 formation of bar (initially formed as spit which grew across a bay joining two headlands)

• 4 lagoon (areas of water dammed by bar) will gradually be infilled with deposition

• 5 (old bay)

• 6 new island which has joined headland through bay

Label what’s going on

• 1 direction of LSD

• 2 direction of prevailing winds

• 3 lagoon

• 4 old bay

• 5 bar

• 6 Joining of two headlands

Formation of sand dune

• Obstacles such as drift wood gets dropped on the beach

• The wind blows sand up the beach which gets trapped of the obstacle

• This creates an embryo dune

• Colonizing pioneer plants like marram grass grow in the dune and stabilize it with their roots and trap more sand

• As plants die they add more organic matter to the sand improving it for other plants to move in

• At the very last stage as organic material increases to almost 40 percent of humus there’s more wood land and a larger distance from the sea

characteristics of sand dunes

• Sand dunes can be small ridges or large hills found at the back of the beach

• Can extend backwards for many miles as well as along beaches

• R vuknerable to erosion by natural processes + human activity

• n important ecosystem supporting unique flora and fauna that have adapted to live within the dune syste

What are corals

Are intervertabrate animals belonging to a large group of colourful and fascinating animals called cindora

What percentage of ocean area do they occupy, what percentage of species rely on them and give examples of countries that have them

• 0.1 percent

• 25 percent

• Madagascar, Japan, west coast of Africa, Belize, Indonesia and autrailia

Amount of salinity needed for them to live on + how water should be

• They need higher salt content so salinility must be 34-37 parts per 1000 (s.w-32 percent to 42)

• Found at depths of less than 25m + water should be clear n clean to allow for optimum photosynthesis to occur

  
  

Amount of light and why + temp and why

• Must be close to the surface couple of meters of tidal zone

• Important to photosynthesis

  
  

• Temp has to be 23-27 degrees Celsius

• Above or below would cause the polyps to die not being able to grow to form larger colonies

Why are corals so important

• Provides habitat and shelter for many organisms

• Provides food for animals (nitrogon and nutrients for marine animals

• Helps with nutrient recycling + purification of water and air +break down of pollutants

• Provides a lot of food for people in developing countries providing jobs such as fishing snd tourism

Main threats to coral reefs

• Climate change - they can’t survive if the temperature is too high and it can cause coral bleaching

  
  

• Coral mining- reefs are used as bricks or road fill

  
  

• Land based pollution such as road construction, deforestation, agriculture and etc - causes disease and mortality, disrupts ecological functions and prevents reproduction

  
  

• Over fishing by doing things like fishing too many big fish or nurseries - disrupts food chain and provides less biodiversity making it weaker to climate change

Sedimentation

• large amounts of sediment blocks polyps (living organisms that make up a coral)

• Since corals rely on polyps to photosynthesis effectively they die without it

Distribution of mangroves

• Found in warm tropical waters

• Highly adaptable to changing conditions

• Covers 25 percent of tropical ecosystems

  
  

Characteristics of mangroves

• Mangroves are trees that grow along the coastline

• They sit in water between 0.5 and 2.5 metres high 

• They need high levels of humidity (75 - 80%) and rainfall per annum (1500 - 3000 mm)

• The ideal temperature for mangrove growth is around 27° C but they are adapting to more temperate climates

• grows at intertidal zone

root system of mangroves

• They have numerous tangled roots that grow above ground and form dense thickets

• The mangrove root system is complex, with a filtration system to keep salt out

• snorkel-like roots that stick out of the mud to help them take in air

Embryo Dunes

• Wind-blown dried sand is trapped by debris and deposition begins

• Pioneer species such as Lyme Grass and Sea Couch Grass begin to colonise

• are very fragile and reach a maximum height of 1 metr

Fore Dunes

• The embryo dunes bring some protection against the prevailing wind

• This allows other species of plant to grow, such as Marram Grass

• Marram grass begins to stabilise the dune with its root system

Yellow Dune

• These are initially yellow but darken as organic material adds humus to the soil

• Marram grass still dominates the vegetation, but more delicate flowering plants and insects are found in the dune slacks

• 20% of the dune is exposed, down from 80% 

Grey Dunes

• Grey dunes are more stable, with less than 10% of exposed sand and have a good range of biodiversity

• Soil acidity and water content increase as more humus is added

• Shrubs and bushes begin to appear

Mature Dune

• As the name suggests, these are the oldest and most stable of the dunes

• They are found several hundred metres or more from the shoreline

• The soil can support a variety of flora and fauna, such as oak trees and alders (climax vegetation)

Distribution of salt marshe

• Coastal areas that are well sheltered, such as inlets and estuaries where fine sediments can be deposited 

• Areas behind spits and artificial sea defences where tidal waters can flow gently and deposit fine sediments

• They form in brackish water (intertidal zones)

Features of salt marshes

• salt marshes are communities of nonwoody, salt-tolerant plants

• They are good coastal defences in some areas, acting as a natural buffer against coastal erosion and flooding

• They begin as tidal mudflats, gaining height as more sediment is deposited This builds up to and above the level, and frequency of tidal flooding, ensuring that the soil never dries out and remains muddy and sticky

biotic components of a coral reef

• producers- seaweed, seagrass, and phytoplankton t provide the nutrients from photosynthesis to coral

• consumers -primary, secondary, and tertiary

• scavengers - feed on dead and decaying plants and animals

• decomposers- bring nutrients back into the ecosystem to support another cycle examples include bacteria

Abiotic features of a coral reef

• Corals need a certain amount of sunlight to survive Too little light and the zooxanthellae will not be able to photosynthesise and produce food for corals Too much light may cause corals to expel zooxanthellae, causing bleaching 

• Depth

• Salinity

Biotic components of a mangrove

• Producers Mangroves are the producers of their own ecosystem organisms feed on the detritus created from falling leaves

• Primary consumers are usually the decomposers (e.g. the mangrove tree crab)

• Secondary consumers are the larger predatory fish, turtles, and crabs

• Tertiary consumers include birds (e.g. herons and ospreys)

Abiotic features of mangroves

• Temperature: Mangroves grow in areas where the temperature isnt below 19°C

• Oxygen: need oxygen to survive. Complex root systems allow the mangroves to receive the oxygen they need by sticking out of the water 

• Salinity: Mangroves have adapted to live in salt water, with some removing excess salt through their leave

• Ocean currents: These distribute mangrove seeds and help keep the areas full of trees 

biotic components of sandunes

• Producers provide the initial beach fuel for dunes include: phytoplankton, (help grow p species)

• Primary consumers: beetles, butterflies, moths,

• Secondary consumers: sand lizards, snakes

• Tertiary consumers: seagulls,  

• Scavengers: crabs, beetles, flies

Abiotic features of sand dunes Wind

• prevailing wind -is needed to blow the dried sand into ridges

• Tidal range – needs to be large to allow sand to dry Water

• a mix of fresh and saline- to support pioneer species

Abiotic features of salt marshes

• Waves – sheltered away from the open sea & destructive waves, usually behind a spit or in sheltered bays

• Tidal Range - this is large with occasional flooding. Mudflats need to be exposed to colonise

• Elevation – needs variation in height to build up mud flats and stabilise marshes

good + services of coastal ecosystem

• Goods- Fish  Shellfish + Seaweed for food industrial use -Medicines Land for Building,  Farming -Construction Materials: Sand  Timber (Mangrove)

• services-protection from: Storms Coastal flooding Rising sea levels. Natural Shelter Recreation Leisure opportunities Biodiversity  Wildlife habitats

industrial threats for coral reefs

• Pollution, overfishing and quarrying of coral for building stone Industrialisation is responsible for the enhanced greenhouse effect

• This leads to rising sea temperatures and sea-level rise putting coral reefs under threat Rising sea temperatures increase levels of coral bleaching

industrial threats to mangrove

• Pollution, overfishing and deforestation for aquaculture -

• Clearance for land development particularly in developing countrie

industrial threats to sand dunes

sand mining

Threats to salt marsh

• Industrial pollution Ideal sites for nuclear power stations  Clearance for development

• commercial and private Development can lead to increased noise and light pollution which may affect wildlife behaviour and nesting