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THE SEA LEARNING OUTCOMES

THE SEA LEARNING OUTCOMES. TODAY WE ARE GOING TO LEARN ABOUT THE ACTION OF THE SEA . AT THE END OF THIS CHAPTER YOU WILL BE ABLE TO DISCUSS THE DIFFERENT WAYS THE SEA CAN ERODE, DEPOSIT AND TRANSPORT ITS LOAD.

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THE SEA LEARNING OUTCOMES

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  1. THE SEALEARNING OUTCOMES TODAY WE ARE GOING TO LEARN ABOUT THE ACTION OF THE SEA . AT THE END OF THIS CHAPTER YOU WILL BE ABLE TO DISCUSS THE DIFFERENT WAYS THE SEA CAN ERODE, DEPOSIT AND TRANSPORT ITS LOAD. YOU WILL BE ABLE TO IDENTIFY MANY OF THE FEATURES FOUND ALONG THE COASTLINE AND DESCRIBE HOW THEY WERE FORMED

  2. THE SEA • LOOK AT THE MAP IN YOUR GEOGRAPHY BOOK. • SEAS AND OCEANS ARE REPRESENTED BY THE COLOUR…BLUE • WHAT PERCENTAGE OF THE WORLD IS SEAS/OCEANS?

  3. FETCH AND WAVES • NO THIS IS NOT SOMETHING WE DO WITH OUR DOG  • When wind blows over the sea it causes waves • The size of a wave depends on its fetch. The fetch is the distance a wave travels. The greater the fetch, the larger the waves

  4. How waves erode • Waves erode in 4 ways • Hydraulic action • Abrasion • Attrition • Compressed air

  5. waves • Waves can be constructive  or destructive  • When a wave breaks on the shore it is called SWASH • When the wave retreats back to the sea this is called BACKWASH

  6. The sea erodes the coastline and this is what it creates • Cliffs • Wave-cut platform • Bays and headlands • Sea cave • Sea arch • Sea stack • Blow holes

  7. WORKBOOK PAGE 24 • COLUMN 1COLUMN 2 • WAVES THEY CAN BE CONSTRUCTIVE/DESTRUCTIVE • FETCH IN IRELAND IT HAS SW DIRECTION • PREVAILING WIND LENGTH OF SEA OVER WHICH WAVE PASSES • SIZE OF WAVES INFLUENCED BY STRENGHT OF WIND COLUMN 1COLUMN 2 A. SWASH THEY CAN CAUSE EROSION ALONG COAST BACKWASH WATER RUSHING TOWARDS THE SHORE CONSTRUCTIVE WAVES WATER MOVING BACK DOWN SHORE DESTRUCTIVE WAVES THEY CAN TRANSPORT AND DEPOSIT

  8. WORKBOOK PAGE 25 • COLUMN 1 COCLUMN 2 • A. ABRASION WAVES HITTING COAST • B. ATTRITION ROCKS AND STONES ERODING • C. HYDRAULIC ACTION AIR TRAPPED IN CRACKS IN ROCKS • D. COMPRESSED AIR ROCKS BROKEN DOWN AND ROUNDED • DESCRIBE THE FORMATION OF CLIFF USING FOLLOWING WORDS/CHART • OVERHANG COLLAPSES MATERIAL IS REMOVED PROCESS REPEATED • COASTLINE RETREATS NOTCH IS CUT BY EROSION

  9. Cliffs and wave-cut platforms

  10. cliffs • Cliffs are vertical slopes along the coast • When the waves hit the coast, rocks are hurled against the cliff wall. • They create a notch (hole) at the base of the cliff which becomes deeper. • Eventually the overhanging rock collapses and the cliff retreats back • Over time it leaves a rock platform called a wave-cut platform

  11. cliffs

  12. Wave cut platform

  13. Bays and headlands

  14. 2. BAYS AND HEADLANDS • A bay is a wide, curved opening into the coast • A headland is a neck of land that juts out into the sea

  15. How are bays and headlands created?

  16. Sea caves

  17. Sea caves • A sea cave is a tunnel that is found at the base of a cliff • The waves attack the rock by hydraulic action, abrasion and compressed air. • The crack develops into a small cave eventually

  18. Sea arch

  19. Sea arch • When a headland is eroded by the sea, it forms a small cave. • Erosion continues to enlarge the cave eventually forming a passage way through to the other side of the headland • Sometimes there can be a cave on both sides of the headland and they meet in the middle to form a sea arch

  20. sea stack/sea stump

  21. A sea stack • A sea stack is like a large pillar standing in the sea • It is formed from a sea arch. • The roof of the cave has nothing to support it so it eventually collapses leaving a pillar called a …………

  22. blowhole

  23. Blowhole

  24. blowholes • When a cave is formed at the base of a cliff, it is continually eroded by the action of the sea • The roof of the cave is eroded by rocks and by compressed air. • Trapped air expands under pressure to cause a mini explosion in the roof of the cave • Eventually the roof of the cave collapses forming a blowhole

  25. The sea transports its load • Longshore drift

  26. Longshore Drift • The waves approach the beach at a 45 degree angle • The swash deposits the heavier material on the beach • The lighter material is carried back out to sea by the backwash • This process is repeated and material is transported along the coast

  27. Features of deposition • So far we have looked at how the action of the sea causes coastal erosion and transportation called…….what’s that word I told you NOT to remember yesterday hhhhhmmmm….Long

  28. A beach and a stormbeach • What is a beach???? • It is a build up of sand and shingles deposited between low and hide tide • What is a stormbeach? • When the weather is stormy the sea has more energy and it can hurl large stones and rocks even further than normal on the beach • These rocks are too heavy to be carried by to sea by the backwash so they remain there

  29. What are sandunes?? • Wind and sandblows in from the sea • It dries the sand on the beach making it lighter it can get trapped in Vegetation on the beach and it piles up to form Sand dunes

  30. Sand dunes with marram grass

  31. The sea deposits its load • Sand spit

  32. Sand Spit is a feature of deposition

  33. Sand spit in Mexico

  34. What is a sand spit and how is it formed?? • A sand spit is a ridge of sand that extends across a bay • It is caused by LONGSHORE DRIFT. • When the coastline changes, longshore drift loses some of its energy and it deposits its load. (it doesn’t have the energy to bring it back out to sea) • Eventually all the material builds up above sea level • The process continues and the sand spit extends all the way across the bay to form a SAND BAR

  35. People and the sea • The sea plays an important role in human activities. • Can you think of 3 ways the sea is important?

  36. 1. Recreation A range of activities includes boating, swimming, fishing and sunbathing 2. Transport Ships can transport bulky cargo across the world. People can travel on car ferries. 3. Food supply Fishing provides us with food. It also creates employment for: fisherman, fish processing factories and in workers in fish shops.

  37. Gabions Groynes

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