3.1.3.3 Coastal Landscape Development

Question 1

Formation of wave cut platforms?(LF of erosion)

Answer 1

High tides crash at one point the cliff between high water mark and low water mark

This creates a wave cut notch due to hydraulic action abrasion and cavitation.

Overtime the wave cut notch expands ti which causes the overhand to collapse and retreat which causes rockfall into the sea

This leaves the base of the cliff to be remained and is only exposed at low tide.

Characteristics :
area of cliff recession
the base is usually 0.5km before the wave competently looses its energy and can no longer erode and reach the cliff mark

Question 2

Origin of headlands

Answer 2

Disconcordant coastline with alternating bands or more resistant and less resistant rocks. This causes differential erosion.

Question 3

Arch/Stack/stump: (lf of erosion)

Answer 3

As the waves pass the cliff they refract and causes distortion and the waves crash into the side of the cliff forming a crack or fault.

Due to abrasion and hydraulic action and cavitation it turns into a cave and then an arch. Due to the weight of the arch being unsupported it collapses to form a stack. After weathering such as chemical weathering it erodes and turns into stump.

Question 4

Sandy beaches (deposition):

Answer 4

Usually formed in sheltered bays
where low energy constructive waves transport sediment and deposits material due to a stronger swash then backwash.

Question 5

‘Outline the role of beaches in a coastal sediment system’. (4)

Answer 5

Store of sediment (temporary) where accumulation occurs from constructive waves & LSD
Also can act as source of sediment if removal occurs eg: destructive waves
Dictated by transfer of LSD in any given area.
Beaches often at dynamic equailibruim to maintain supply of material and sediment.

Question 6

Term for when the beach grows

Answer 6

accretion

Question 7

Landforms of deposition: offshore bar

Answer 7

As destructive waves have a strong backwash they take sediment from the beach to the offshore and due to friction the waves slow and deposited as an offshore bar.
One example is slapton sands in devon

Question 8

Landforms of deposition Spits:

Answer 8

Spit forms on drift aligned beaches. Lattoral drip transports material along the coast. When there’s sudden change in direction of coastline the sediement will still conintue to be deposited in the same direction. Salt marshes may form behind the spit as it passes over an estuary. End of spit may curve due to wave refraction craving material towards sheltered area. Spits usually stop due to outward flow of river.

Question 9

Simple vs compound spits?

Answer 9

Simple is straight
compound is more older and curved recurved at end

Question 10

Formation of tombolo:

Answer 10

Tombolo forms on a drift aligned beach. Longshore drift transports material along the coast. It continues to deposit and transport material even after sudden change in coastline in the same direction. It will continue until the spit connects the mainland to an island. One example is chisel beach in Dorset.

Question 11

Saltmarshes and succession:

Answer 11

Succession of plant growth occurs from saltwater to climax begiation is haloserre

The sea deposits material and mud behind spits. Mud builds up due to flocculation and around roots of pioneer plants such as eelgrass.
Plants decompose and add nutrients so number of species increase.Vegiation increases and mud accumilaes as it breaks the surface of water. Eventually land base plants can colonise

Question 12

Formation of barrier beaches:

Answer 12

Barrier beaches are long narrow islands of sand that run parallel to the shore and is detached.

A barrier beach is usually formed as an extension to a spit
longshore drift moves sediment along the coastline until there is a change in coastline. A split develops usually and a bay and once the spit develops accros entire bay a bearrier beach formed. Colonisation by vegetation can stabilise the barrier beach and trap further sediment keeping the barrier above sea even at high tight.
The leawardside may have lagoons and be colonies by mangroves.

Question 13

Formation of sand dunes:

Answer 13

Sand dunes are coastal sand hill above the high tide mark shaped by wind action covered with grasses and shrubs.

Obstacles on the beach causes blown sand to accumulate
embryo dunes begin to build up and marram grass begins to grow
marram grass roots go deep into the sand and stabilise the embryo dune and is adapted to grow in dry sandy and saline conditions.

The older dunes migrate inland as new embryo dunes are made. When the grasses die they rot and add more nutrients to the sandy soil which means more plants can survive and grow.
Mature dunes can be up to 15 m high

Question 14

What is an estuaries?

Answer 14

Where fresh river water means salty ocean water which results in brackish water.

Question 15

Formation of estuaries:

Answer 15

River spreads out and slows down as it approaches the sea,
Deposition is therefore encouraged as the rivers becomes less efficient the bigger sediment is dropped first.
Salinity increases towards the sea.
Layers of sediment build a marsh into the sea that is only exposed at low tide.
This causes bars or islands of sediments to build in them middle of the channel which creates mudflats.

Question 16

Formation of salt mash - deposition:

Answer 16

The sea deposits sediment and mud behind the spit close to high tide mark.
Mud builds up due to flocculation and as a result pinoeer plants such as eel grass colonise in the intertidal zone as they are halophytic and help with the binding and trapping of mud.
Mud accumilates and breaks the surface of water above high tide mark.
Plants decompose and add nutrients to soil meaning more species can colonise until climax community is reached.

Question 17

What is eustatic change?

Answer 17

A global change in sea level resulting from an actual fall or rise in the level of the sea itself relative to the centre of the Earth

Question 18

What is isostatic change?

Answer 18

local change in sea level resulting from the land rising or falling relative to the sea

Question 19

Isostatic change rises relative to what?

Answer 19

Land rises relative to sea level

Question 20

Isostatic In uk

Answer 20

Since the glaciers is melted up north the land is rising 3mm a year due to isostatic rebound this induces a sea saw effect to which the south is sinking not the sea level rising

Question 21

Impacts of sea level climate change: changes in coastline

Answer 21

Over last 10,000 years sea level rise has separated Britain from rest of europe

Question 22

submergence of low lying island:

Answer 22

If sea level rose by 0.5m then the most of Maldives will be submerged.

Question 23

Formation of Rias:

Answer 23

Rias is a landform of submergence. Rias is formed when valleys are partially submerged due to eustatic rise being faster then isostatic adjustment and the sea level rises relative to coast. This forms a gentle long and cross profile with having a wide mouth and becoming more narrow and shallow futher inland. One example is salcombe in Devon.

Question 24

Formation of Fjords:

Answer 24

First a glacier charges its wave creating a U shape valley called the glacial trough. Eustatic rise submerges the glacial trough. Each side of the valley has a steep gradient. Fjords have a shallow entrance due to a threshold due to glacials depositing material as it melts deeper inland.
example - sognefjord in norway

Question 25

Formation of Dalmatian coasts:

Answer 25

Tectonic movement folded the crust upwards to form Anticlines and Synclines. The sea levels rise and flood the synclines. This forms parallel bars of islands to coastline called Dalmatian coastline. eg spalato in croatia

Question 26

Landforms of emergence: Raised beaches:

Answer 26

As sea levels fall, it exposes wave cut platforms and as the sea level falls relative to the coast new coastline emerges. Overtime beach sediment becomes vegetated and becomes soil.

Question 27

Relic cliffs:

Answer 27

Cliffs above raised beach are no longer eroded by sea and gets covered by vegetation and is slowly degraded overtime.

Question 28

Marine platform:

Answer 28

A large flat area that was previously the wave cut platform but is now left exposed ie: not covered at high tide at all.

Question 29

Drift aligned vs swash allined beaches?

Answer 29

Drift-aligned beaches form where longshore drift moves the sediment along the beach as waves approach at an oblique angle This will often culminate in a spit where the coastline changes direction Swash-aligned beaches form where the energy is low The waves are more parallel to the shore in swash-aligned environments so there is very little horizontal or lateral movement of sediment

Question 30

Formation of sand dunes:

Answer 30

Sand dunes are formed in areas where there is a large quantity of sand, a large tidal range and onshore prevailing winds When sand is trapped towards the back of the beach due to an obstacle dunes will develop Pioneer plant species hold the sand together and stabilise the dune Other plants are then able to thrive in the environment which leads to the development of the dune ecosystem, this is called plant succession