Marine Processes

1. Marine Processes

2. Movement of Water • Water is set in motion by: • Waves; • Tides; • Currents.

3. WAVES • ROUGHEN THE WATER SURFACE CURRENTS • COLD AND WARM WATER STREAMS THAT FLOW FASTER THAN THE SURFACE WATER

4. Tides

5. Shallow_water_wave Deep_water_wave

6. 1) Waves. Most waves are generated by wind. Amplitude depends on wind velocity and persistence. Period: time required for two successive crests or two successive troughs to pass a point in space. Wavelength (L): the distance between adjacent points on a wave that are in phase (i.e., moving in the same direction & displaced the same distance from the undisturbed water level.

9. Constructive Waves Spilling Breaker Powerful Swash Weak Backwash  Tom Abbott, Biddulph High School and made available through www.sln.org.uk/geography and only for non commercial use in schools

10. DistructiveWaves Crashing breaker Weak swash Powerful Backwash

11. Erosion Hydraulic action Corrosion/solution Corrasion/abrasion attrition

13. Cliff line Joints and beds allow waves to attack the cliff more easily HIGH TIDE LEVEL Waves can use rocks to erode the cliff Wave cut platform Wave cut notch  Tom Abbott, Biddulph High School and made available through www.sln.org.uk/geography and only for non commercial use in schools

14. The force of the waves pushes air into cracks in the rock The compressed air exerts enormous pressure at the tip of the crack. As the water falls back the air pressure is released and rock is pulled out from the crack further enlarging the hole.

15. Old cliff line Original Land surface stack stump Natural Arch Wave-cut platform

16. Development of a Headland 1

17. Development of a Headland 2

18. Development of a Headland 3

19. Coastal Erosional Landforms • Sea arches • Sea stack

20. SEA CAVE

22. Cliffs and wave cut platforms

23. main features of a wave cut platform • Bare rock surface/sandstone/resistant rock • May have rock pools • May be covered with seaweed • Exposed at low tide/covered at high tide • Remains of former cliff base/at foot of cliff • Flat/gently sloping • Smooth

24. Wave cut platform formed between the high and low tides as the waves only attack the cliff and pass over the platform

25. Bay • Features are formed by either erosion or deposition • outcrop of less resistant rock/weak rock/soft rock • eroded rapidly by sea • differential erosion occurs/hard rock erodes more slowly than soft rock • by processes such as hydraulic action/abrasion

26. coastal erosion may cause problems for the people who live in the area • Destruction of houses/bungalows/homes • Loss of gardens • Need to evacuate • Threat to businesses/hotel/craft shop • Loss of income from tourists • Loss of part of car park etc.

27. Coastal Deposition • Sediments accumulate where wave energy is low • 3 principal sources of coastal sediment: • Streams • Delta • Estuary • Coastal cliff erosion • Offshore sources

28. Delta • Deposition of sediment/alluvium by river, as speed of flow slows down/cannot carry load, especially if river is heavily laden with silt, • absence of major tidal flows/currents, • impact of salt water causes further deposition, • growth of vegetation raises it above sea level, • distributaries form

29. Delta(USA) • Deposition of sediment/alluvium by river, as speed of flow reduced when it reaches Gulf of Mexico so it slows down/cannot carry load, especially as river is heavily laden with silt due to it eroding its banks in states such as Missouri, • Absence of major tidal flows/currents in Gulf of Mexico, impact of salt water causes further deposition, • Growth of vegetation raises it above sea level, • DIstributaries form as the channel splits south of New Orleans

30. Beach • formed by constructive waves • stronger swash than backwash • materials deposited • materials build up over time • refraction of waves in bay

31. coastal sand dunes • Deposition by wind as energy is reduced • Onshore winds pick up dry sand from beach • Obstruction on beach/pebble/seaweed causes eddies/sheltered area • Marram grass colonises dunes and traps further sand

33. conditions which lead to the development of a coastal marsh • shallow water; in estuary • sheltered water; behind sand spit • where deposition will occur; because of slow moving water • mixture of salt/fresh water • encourages flocculation/sediment to sink to bottom • tidal area; encourages growth of salt resistant • vegetation etc

39. Conditions required for the growth of coral reef • Warm water/seas; temperatures above 20 °C • Shallow water; not more than 60 metres deep • Water free from sediment/clear/away from deltas/rivers • Plentiful supply of oxygen in water/unpolluted • Plentiful supply of plankton • Calm seas/lack of destructive waves

40. TYPES OF CORAL REEFS • FRINGING REEF • BARRIER REEF • ATOLL

44. Islands and Coral Reefs • Coral Reefs • Shallow, wave-resistant structures • Remains of tiny sea animals (skeleton of calcium carbonate) • Types of Reefs • Fringing reef • Barrier reef • Challenge for human habitation

45. human activities can damage the natural environment in coastal areas. • Tourists walking through shallow reef waters damage coral structures • Noise/wash from ships could scare fish • Litter from tourism • Sewage outflows pollutes seas • Overfishing has left stocks of fish seriously depleted • Impacts on ecosystems/food chains • Visual impacts of developments

46. THANK YOU

47. Bibliography http://www.bbc.co.uk/schools/gcsebitesize/geography/ http://home.freeuk.com/ http://geobytesgcse.blogspot.com/ http://www.geography.learnontheinternet.co.uk/ http://whs.moodledo.co.uk