1
Q
Example of sand dunes
A
Newton burrows
2
Q
Wht conditons are important in the formation of sand dunes
A
- Large macro tidal rage 7m +
- Wide sandy beaches with sediment supply
- Offshore sand bars
- low beach gradient
- strong prevailing onshore winds
- area of inland space for the dunes to develop from - vegetation such as a marram grass to colonise the dunes after formation to help to bind the dunes.
3
Q
what other than wave errosion helps to errode the beach and how
A
- Aeolian erosion - Saltation ( dry sand particles move and bounce along the beach) and creep ( the collision of one sand particle hitting another one, allowing them to move around the beach.
4
Q
What percentage of dry sand is moved by saltation, creep and suspension
A
- 95 % - saltation
- 4% creep
- 1% suspension
5
Q
How high and how far do sand grains move via saltation on average
A
- height = less than 5cm
- horizontal 5-10 cm
6
Q
What is needed for sand to be deposited
A
- Reduction of wind velocity
- Plants and obsticles can help
7
Q
How does the sediment supply impact the dunes
A
- Low supply, sand can be blown inland from the dune moving the due system inland, making the dunes more susceptible to erosion and blowouts.
- loose sand may be reformed as parabolic dunes behind the blow outs.
- Excess sediment
- A whole series of dune ridges can be made. dunes usually begin to form from the spring high tide level.
8
Q
A
9
Q
What impacts the formation of dunes
A
- sediment supply
- obstacles in the way
10
Q
Why are plants benifitial to the sand dunes formation
A
- The roots stabilise the sand and bind it together
- the plants have a frictional effect with the wind slowing it and reducing the wind energy causing the depositing of sand increasing the supply for the dunes
- When plants die they produce hummus which increases the fertility of the soil and allows larger plants to grow
11
Q
What is the order of the diffrent types of the dunes youngest to oldest
A
- Embryo, fore, yellow, gray, mature
12
Q
Which are the 2 types of dunes to do with movement
A
- Mobile and fixed
13
Q
Which dunes are mobile
A
- Embryo - yellow
14
Q
what are slacks
A
- The dipped areas between dunes
15
Q
How are dune slacks erroded
A
- Human influence (reduce number of plants decreases the erosional protection.
- Wind erosion
Wind funnels through gaps between the dunes (like a wind tunnel)
This accelerates wind speed locally, increasing erosion
16
Q
What is a dune blowout
A
A dune blowout is a depression or hollow in a sand dune caused by wind erosion.
17
Q
How are dune blowouts caused
A
- Removal of vegetation
- A positive feedback loop
- Loss of vegitation - sand removal - increased wind speeds as less friction from plants - more mobile sand - greater difficulty of vegetation reestablishment
18
Q
what happeneds to the size of sediment down stream
A
- Decreases down stream
19
Q
Where does the sediment found in an estruary come from
A
- Fluvial / glacial sediment
- Estuary margin sources
- Sources from outside the estuary itself, eg LSD
20
Q
What is a tidal mudflat
A
A tidal mudflat is a flat, low-lying area of mud exposed at low tide and covered at high tide.
- Formed from silt and clay, deposited by water moving slowly.
21
Q
How are fluvial processes important in the formation of mud flats
A
Rivers carry silt, clay, and fine sand downstream
When the river meets the tidal water of an estuary, its velocity slows
Fine sediment settles out, forming mudflats
- At high tide water rushes over the flats and redistribute sediment
Low tides expose mudflats, showing the deposited material
22
Q
What are salt marshes
A
- Sheltered areas of low energy, in the intertidal range eg behind spits where tides rise and fall and deposit mud and silt.
23
Q
Where do salt marshes form
A
- In the lower part of the river where it meets the sea - the sea and the river meet, and both lose energy and therefore deposit the sediment
24
Q
Describe the formation of spits
A
- Deposition of fine sediment
River slows in the estuary → sediment settles
Tides deposit more material
Salt-tolerant plants called halophytes colonise the mud
Plants trap more sediment due to friction and stabilise, the marsh
Marsh gradually rises in height. So its covered by the sea for a shorter period of time, allowing less salt-tolerant plants to establish themselves = succession
25
Give an example of a spit and salt marsh
- Ogmore by sea
26
What is needed for a saltmarsh to form
- low energy tidal environment
- Plants need to be able to establish
- sediment accretion
27
What si sediment accretion
- The building up of sediment
28
What happeneds if the rate of sediment accretion is high
- The low marsh areas are elevated at a faster rate, making the platform almost horizontal overtime
29
What is the sward side
The side near the back of the beach
30
What effects the formation of salt marshes
-Weather
- River regime
- sediment supply
-Anthropogenic influence
- Sea level
- Climate
- Wave type
- Tidal regime
31
Where are mangroves found
- 20-30 degrees each side of the equator
32
Where do mangroves form
- Close to coasts
- In sheltered muddy shores where there is a good supply of sediment
33
What do mangroves produce
- low-lying forest canopy that is adapted to thrive in salty waters and waterlogged environments
34
How tall can mangroves reach
- In exess of 30 metres
35
What 2 types of roots do red mangroves have
- prop roots and stilt roots
36
How are they addapted to the salty conditions
- They excrete salt from filters in their roots and store salt in their older leaves and bark
37
How are mangroves anchored
-They have multiple areal tap roots that emerge from the trunk, above the mud which anchor the tree.
38
How are the areal tap roots useful
- O2 uptake
- Helps to trap the sediment
- Help to anchor the tree
39
Why are we loosing mangroves
- Shrimp farming tournisum and urbanisation
40
At what rate are we loosing our mangroves
1% per year
41
Why are mangroves important
- Protect the coastline from errosion
- provide a habitat to a diverse ecosystem including some species of tiger and manatees.
- helps to flocculate the sediment and keep the reefs clear and allow sunlight through
42
What is a corral reef
- A living structure that are anchored to the seabed
43
What are some parts of the corral reef ecosystem
-Polyps
- Zooxanthellae
44
what is a Polyup
- A tiny marine animal
45
Where do polyups live
In rocky calcuim carbonate strucures
46
What do polups do
- Secrete the calcium carbonate that makes up the rocky material that protects them
- They live in the rocky structures that protect them, which they secrete
- Polyps build the coral reef
- Remove carbon dixide from the sea and uses it to form there calcuim carbonate skeleton in a prosess called calcification
47
Give an example of a symbiotic relationship in the corral reef
- Polyps have a symbiotic relationship between the colourful algae (Zooxanthellae) that live inside the coral. In return they provide food to the polyp via photosynthesis
48
What is the colourful algea called that shares the symbiotic relationship between thepolups
- Zooxanthellae
49
What does the zooxthanelae do
_ Provide food for the polyups via photosynthisis
- Help in the carbon cycle by using the CO2 in the ocean
50
Why are corral reefs important
- Control the amount of carbon in the sea
- Protects the coastline from errosion
51
How are corral reefs formed
- Start with polyups attaching themselves to a hard surface in shallow seas where there is sufficient light for growth
- Polyus secreate calcuium carbonate forming their skeleton
- as they grow and die these colonies form ciral reefs
- Zooxanthellae recieves shelter from the polyp and provides the polyp with food via photosynthisis
- An island gets surrounded by a fringing reef that grows in the shelter of the island
-The polups die and new ones grow ontop and increase the hight of the reef over time
- An atoll is formed if the reef grows over the island and the island disapears beneath the sea
52
What does the morphology of reefs look like
- The fetch-facing side is usually eroded by the breaking waves, and the leeward side is usually where the new coral colonies are developing.
53
What conditions are needed for the corral reef to form
- Clear sea to allow for light penetration
- tropical waters between 23 and 29 degrees
- sea salinity between 30 ppt and 40 ppt
- Shallow water no deeper than 100 m
- well aerated water resulting from strong wave activity
54
How are mangroves formed
- Location
- Large intertidal range
- Sheltered
- sediment supply
- pioneer plants halophytic to encourage the animals and plants to colonise
- trap and flocculate sediment, stabilise sediment overtime
Commonly behind barrier islands, spits, or coral reefs
Creates mudflats, which are the base for mangrove growth
Mangrove seeds (called propagules) are buoyant
They float in tidal water until they settle in the mud
Once anchored, they begin to grow roots
55
What are the 3 types of corral reefs
- Frindging
- Barrier
- Atoll
Issy As-Level geography
flashcards
Decks in class (13)
# Cards
-
Topic 1.1.1 operation of the coast system17
-
Topic 1.1.2 temporal variations and their influence on the coastline32
-
Topic 1.1.4 Factors affecting coastal processes and landforms40
-
JCL - Plate margins8
-
Volcano JCL - E15 Case study28
-
Earthquake JCL - Case study48
-
1.1.3 - landforms and landscape systems20
-
1.1.552
-
1.1.647
-
1.1.755
-
1.1.823
-
JCL Volcanoes2
-
Geography fieldwork study61
