Enquiry Question 1 - Key Idea 3

Question 1

What is Key Idea 3?

Answer 1

Rates of coastal recession and stability depend on lithology and other factors

Question 2

Meaning of rates of recession:

Answer 2

How fast a coastline is moving inland.

Question 3

What are the three rock types:

Answer 3

• metamorphic
• igneous
• sedimentary

Question 4

Examples of igneous rock

Answer 4

• Granite
• Basalt
• Dolerite

Question 5

Examples of metamorphic rock

Answer 5

• Slate
• Schist
• Marble

Question 6

Examples of sedimentary rock

Answer 6

• Sandstone
• Limestone
• Shale

Question 7

What is the lithology of igneous rock?

Answer 7

They are crystalline with interlocking crystals

Question 8

What is the structure of igneous rock?

Answer 8

Rocks such as granite have a few joints so there are limited weaknesses

Question 9

What is the erosion rate of igneous rock?

Answer 9

Very slow. The interlocking crystals make for strong, hard erosion-resistance rock.
Rocks such as granite have few joints, so there are limited weaknesses.

Question 10

What is the lithology of metamorphic rock?

Answer 10

Crystalline. Many exhibit a feature called foliation, where crystals are all orientated in one direction (producing weaknesses)

Question 11

What is the structure of metamorphic rock?

Answer 11

They are often folded and heavily fractured

Question 12

What is the erosion rate of metamorphic rock?

Answer 12

Slow. They are resistant to erosion. Many exhibit a feature called foliation, where crystals are all orientated in one direction (producing weaknesses). They are also often folded and heavily fractured, which are weaknesses that erosion can exploit.

Question 13

What is the lithology of sedimentary rock?

Answer 13

Clastic and are younger than igneous and metamorphic rock.

Question 14

What is the structure of sedimentary rock?

Answer 14

Tend to have many bedding planes and fractures e.g shale. The weakness materials is known to be unconsolidated sediment. However, some limestones and sandstones are actually crystalline sedimentary. They have been compressed and compacted over hundreds of millions years.

Question 15

What is the erosion rate of sedimentary rock?

Answer 15

Moderate - fast. Geologically younger rocks are weaker and therefore erode faster.

Question 16

Permeable rocks:

Answer 16

Allows water to flow through the rock.
- Includes many sandstones and limestones

Question 17

Impermeable rocks:

Answer 17

Do not allow groundwater flow
- Include clays, mudstones, and most igneous and metamorphic rocks

Question 18

Permeability is important because…

Answer 18

groundwater flow through rock layers can weaken rocks by removing the cement that binds sediment in the rock together.
+ can create high pore water pressure within cliffs - affects stability
+ water emerging from below ground onto cliff face at a spring can run down a cliff face and cause surface runoff erosion, weakening the cliff
+ groundwater flow and pore water pressure can cause slumping in unconsolidated sediments on the cliff top

Question 19

Pore water pressure:

Answer 19

The pressure water experiences at a particular point below the water table due to the weight of water above it

Question 20

Why are coasts difficult for vegetation to grow?

Answer 20

• Because coasts are high saline / salty environments so vegetation needs to adapt and it leads to plants becoming inundated
• There is a lack of hummus (dead, organic materials) so soil lacks nutrients
• Destructive waves / storms could damage vegetation
• Erosion can damage plants

Question 21

What is the importance of vegetation at the coast?

Answer 21

• Provides shelter/habitat for organisms (coastal species)
• Help add nutrients to sand by litter (due to decomposition when the plants lose their leaves and die)
• Roots of vegetation stabilise sand and soil, reducing the rate of erosion, as landscapes become more stable (roots bind sediment particles together)
• Prevents flooding by providing a barrier between land and sea
• When submerged, plants growing in sediment provide and protective layer, the surface of the sediment is not directly exposed to moving water and therefore erosion.
• Plants protect the sediment from wind erosion by reducing speed at the surface.

Question 22

Pioneer species

Answer 22

Highly adaptive to challenging environments. They allow less adapted species to colonise the area creating a climal community.

Question 23

What happens as Pioneer species die

Answer 23

They die and drop off organic material, making the soil more nutrient dense, allowing more dense vegetation to grow

Question 24

Plant succession

Answer 24

The evolution of plant communities at a sight over time - from pioneer species to climate vegetation

Question 25

Halosere

Answer 25

Mud flat / salt marsh environment, inundated

Question 26

Psammosere

Answer 26

Sand dune environment, dry

Question 27

Xerophytic

Answer 27

Plants adapted to incredibly dry environments with very little nutrients (deep roots, leaves with small surface area to reduce water loss) e.g marram grass which have roots up to 3m deep.

Question 28

Halophytic

Answer 28

Plants adapted to survive in environments with high concentrations of salt, thrive in hacoseres. (e.g Samphire)

Question 29

Why is plant succession so important in Haloseres and Psammoseres?

Answer 29

- The roots of pioneer species stabilise the sediment, preventing it from erosion - Decomposition of pioneer species allows more nutrients in the soil, allowing for colonisation of less adaptive plant species

Question 30

What are the similarities and differences between the haloseres and psammoseres?

Answer 30

- Halosere environments are inundated whereas psammoseres are very dry - Psammosoes have a lack of nutrients whereas haloseres have an abundance of nutrients - Both have plant succession occuring - Both have coastal accretion - Both are in low energy environments

Question 31

Foredune

Answer 31

An object such as a plant or rock causes sand to build up on the lee side

Question 32

Mobile dunes

Answer 32

Plants begin to bind sand together

Question 33

Semi-fixed dunes

Answer 33

The dunes could be 20m high here

Question 34

Explain the formation of embryo dunes

Answer 34

Early accumulations of sand at the back shore where dry sand is blown on shore at low tide and accumulates around rocks and wood. these accumulations are prone to wind and wave erosion during storms

Question 35

What are dune slacks

Answer 35

At high tide or under storm conditions, sea water may reach dips in the sand dunes, called slacks and collect. blow out caused by strong winds stops when it reaches damp sand at the water table as damp and is less easily blown away.

Question 36

Apart from colour what distinguishes yellow dunes from grey dunes

Answer 36

Grey dunes are older with fixed by developing vegetation and have a higher humus content. grey dunes tend to be more acidic. due to the grater vegetation cover and roots from the vegetation mean they are more stable.

Question 37

Why is marram grass important for the formation of sand dunes

Answer 37

Effective in stabilising blown sand and acts as a natural buffer to erosion of the areas behind it. flexible waxy leaves which can cope with harsh environment of the coast (water deficient environment). it has roots up to three metres long so can reach water far below the surface and also the anchoring roots provide strength and stabilising properties.

Question 38

Explain why estuaries are ideal for the development of salt marshes (6)

Answer 38

They are normally sheltered stretches of water and the lack of strong waves, this encourages the deposition of mud silt. sediment is supplied to an estuary by its river. this is added to by the marine sediment flowing into the estuary at high tide. mudflats are gradually built up in the sheltered water and they will eventually be colonised by the pioneer plants. those plants prosper in the sheltered conditions and help trap more sediment. so the plant succession is set in motion.

Question 39

What is the final stage of salt marsh succession called?

Answer 39

Climax Vegatation

Question 40

What is the correct order of plant succession of a sand dune?

Answer 40

Embryo dunes, foredunes, yellow dunes, fixed dunes, health/woodland

Question 41

How does vegetation stabilise sediment?

Answer 41

As the roots of vegetation bind sediment particles together, stabilising the sand and soil to become more stable, reducing the rate of erosion. When submerged, plants growing in sediment provide a protective layer, so the surface of the sediment is not directly exposed to moving water and therefore erosion.

Question 42

Sand dune succession formation:

Answer 42

1- Begins with colonisation of embryo dunes by pioneer species. They stabilise mobile sand with their root systems. 2- Embryo dunes alter environment conditions from harsh salty mobile sands to environment conditions from harsh salty mobile sands to environment other plants can tolerate 3- New plant species colonise embryo dunes creating foredunes 4- Soil develops, nutrients/water become more available so plants that had better conditions can concieve the area. 5- Dune slacks: periods of raw erosion can create low areas 6- Foredunes become more stabilised and grow to yellow dunes 7- Other species are introduced, e.g marram grass, eventually grey dune forms 8- New embryo dunes form as long as there is a supply of sediment returns, this protects original dune, allowing vegetation.

Question 43

Salt marsh succession:

Answer 43

1- Starts in low energy environments, e.g estuaries since they are sheltered from strong waves so sediment can be deposited 2- Algal stage: (e.g blue green algae) grow on and within bare mud, binding it together 3- Pioneer stage: (e.g glasswart) roots begin to stabilise the mud allowing further mud acretion 4- Establishment stage: (e.g Salt marsh grass) a continous carpet of vegetation is established and the salt marsh height increases 5- Stabilisation: (e.g Sea lavender): this area of salt marsh is rarely submerged 6- Climax vegetation: (e.g rush, sedge): developed soil profile and only submerged for x2 each year.

Question 44

Example of Algal stage

Answer 44

Blue green algae

Question 45

Example of Pioneer stage

Answer 45

Glasswart

Question 46

Example of Establishment stage

Answer 46

Salt marsh grass

Question 47

Example of Stabilisation (plant)

Answer 47

Sea lavender

Question 48

Example of Climax vegetation

Answer 48

Rush, sedge