The Work of the Sea

Junior Cert Geography slides on the work and activity of the Sea - coastal processes, coastal erosion, coastal deposition and features.

1. The Work of the Sea

2. Erosion – rocks are worn down and broken into smaller rocks Transportation – rocks and sand are moved from one area to another by waves and sea currents Deposition – material is deposited (dropped) in some areas, forming beaches and sand dunes Processes at work in the Sea

3. Hydraulic Action – force of moving water Compressed Air – air gets trapped in rock, the pressure of the air can crack rock Abrasion – rocks and stones can be thrown against the coastline, wearing it away Attrition – rocks and stones are worn down themselves How Waves Erode

4. Name the erosion process?

5. Formation of Bays and Headland s The hard rock in a coastline erodes more slowly than the soft rock The hard rock that has not eroded, juts out to the sea, forms a headland . The spaces between the hard rock are known as Bays BAY BAY Headlands

6. Sea Cliffs – Cliffs of Moher

7. Formation of Cliffs – steep parts of the coast A Cliff is formed when Waves erode the coast and form a small notch. The erosion continues until the notch gets bigger. The section of rock above the notch cannot be supported anymore and collapses. The slope becomes steeper A cliff is formed . The former base of the cliff remains as a wave cut platform.

8. Sea Caves , Sea Arches , Sea Stacks

9. Formation of Sea Caves A large hole or tunnel at the base of the Cliff is called a cave. If there is a weak spot such as a crack or a joint in the rock, the waves will attack it and erode a passage called a sea cave

10. If a Cave erodes right through a headland (or if two caves erode from each side) an arch is formed If the roof of an arch collapses, a sea stack is formed The sea stack can eventually be eroded down to a stump . Formation of Sea Arches

11. Sea Stack

12. Formation of a Blow Hole Draw diagram p54 A blow Hole is a hole which joins the roof of a cave with the surface above.

13. 2011 Junior Cert

14. Transportation by the Sea

15. Waves approach the shore at an angle. The swash of each wave pushes material up the beach (A-B). Because of the slant the backwash drags the material straight down (B-C) The process is repeated so the material is transported (moved) along in a zig zag pattern. Long Shore Drift

16. How can you stop Long Shore Drift? A Groyne is a low wall built into the sea to stop long shore drift.

17. Sea Deposition A beach is a gently sloping area of sand, pebbles or stones along the shore. It lies between the high-tide mark and the low-tide mark. It is formed by the swash pushing materials up the beach and the weaker backwash pulls finer materials back down. Formation of a Beach:

18. A Storm Beach is formed when large stones are deposited at the top of a beach during a storm.

19. Sand Dunes Sand dunes are mounds of sand at the back of a beach. Sand dunes are formed because of the wind blowing the sand inland.

20. Marram Grass Marram grass is long, dry and has long roots. These roots bind the sand together and protect it from the wind and the rain

21. The Formation of a SPIT

22. A sand spit is a ridge of sand or shingle that juts out into the sea. Long shore drift stops when it reaches a bay or sheltered place. The material may build up gradually to form a spit. Eg. Portmarnock, Co. Dublin The formation of a SPIT

23. Formation of a SAND BAR

24. A sand bar is a sand spit (explain formation) that stretches across a bay to connect the two sides of the bay. The lake behind the sand bar is called a lagoon Example: Lady’s Island, Co. Wexford Formation of a SAND BAR

25. Formation of a TOMBOLO

26. A tombolo is a ridge of sand or shingle that joins an island to the mainland A tombolo forms when a sand spit juts out into the sea and links with an island Example: Sutton, Co Dublin Formation of a TOMBOLO

27. 2012 Ordinary Level Junior Cert

28. 2011 Higher Level Junior Cert

29. 2010 Junior Cert Higher Level

30. Defence: Protecting land and people from erosion Economic activities: Making money from the sea and its resources. Interaction with the Sea

31. Made of Reinforced Concrete Stops waves from eroding land away Has NO effect on Longshore drift Expensive to build Defence – Sea Walls

32. Also known as “Rock Armour” Simple to build, cheap Can cause safety concerns and look ugly Has NO effect on longshore drift Defence - Boulders

33. Low walls, built at right angles to the coast Made of wood (cheap) or concrete (expensive) Reduce longshore drift Defence - Groynes

34. “Walls” made of wire mesh filled with stones Reduce Erosion Cheap to build – but can cause safety concerns and do not last too long Defence - Gabions

35. Economic use of the Sea - Fishing

36. Economic Use of the Sea – Tourism/Recreation

37. Economic use of the Sea – Wind Energy

38. Economic use of the Sea – Wave Energy

39. Economic use of the Sea – Fossil Energy

40. Litter from people at the coast Overfishing and damage to wildlife Oil Spills and pipe breaks Misuse of the sea - pollution

41. 2008 Leaving Cert Higher