1. LITHOSPHERE CORE COASTLINES 1 MARINE EROSION PROCESSES. Read the course booklet. You will need to know and be able to explain the four methods of coastal erosion and two of weathering The next few slides illustrate these processes.

2. LITHOSPHERE CORE COASTLINES 2 The force of waves hitting a cliff (or sea wall) compresses water and air into cracks and joints. This increase in pressure may lead to cracks widening and pieces of rock breaking off. Hydraulic Action

3. LITHOSPHERE CORE COASTLINES 3 Abrasion Rock fragments may be picked up by waves and thrown against the rock face of cliffs by subsequent waves. Sometimes the softer strata are abraded more than the harder ones, giving a striped appearance. Abrasion is most effective at the base of cliffs.

4. LITHOSPHERE CORE COASTLINES 4 Wave attrition Rock fragments are worn down into smaller and more rounded pieces. Currents and tidal movements cause the fragments to be swirled around and to grind against each other. This type of erosion produces pebble beaches.

5. LITHOSPHERE CORE COASTLINES 5 Water- layer weathering Alternative wetting and drying -as happens with the rise and fall of the tides -can disintegrate porous or coarser rock layers. Salt crystals growing in rock spaces can do the same thing.

6. LITHOSPHERE CORE COASTLINES 6 Corrosion (solution) Salts and acids in sea water can react with rocks, slowly dissolving them away.

7. LITHOSPHERE CORE COASTLINES 7 Rates of erosion depend on many factors: Waves – strength, frequency, height Weather – frequency of storm conditions Geology of the coastline : -type of rock -orientation of stratification (the way the bedding planes in the rock face the sea)

8. LITHOSPHERE CORE COASTLINES 8 The FETCH is the distance travelled by waves from one shore to another. The waves hitting the southwest coast of England have a fetch of about ten thousand miles!

9. LITHOSPHERE CORE COASTLINES 9 Many erosion features are a result of rocks of varying hardness occurring beside/below each other. The DIFFERENTIAL EROSION between them creates the landform.

10. LITHOSPHERE CORE COASTLINES 10 There are eight erosion-related features you need to learn. In groups of 4 using a new text book each you will make notes on all the erosion features... You all need to be able to ;- Describe them using their proper terms Explain IN DETAIL how they form Draw simple LABELLED SKETCHES of them Give EXAMPLES of them in the UK. BAY AND HEADLAND CAVE AND BLOWHOLE ARCH STACKSTUMP WAVE-CUT PLATFORM NEEDLE ABRASION NOTCHES

11. LITHOSPHERE CORE COASTLINES 11 See how the base of this cliff is being broken up by the attrition of the cobbles- and litter- at its high tide mark. Note the softer layer of shale at the cliff foot! Abrasion notches

12. LITHOSPHERE CORE COASTLINES 12 Headland erosion near Noss Point Caithness The sea is eroding this headland back leaving a wave- cut platform below the waves.

13. LITHOSPHERE CORE COASTLINES 13 There is a copy of this diagram to stick into your jotters.

14. LITHOSPHERE CORE COASTLINES 14 How Are Wave Cut Platforms Formed? Erosion is greatest when large waves actually break against the foot of a cliff. The foot of the cliff is undercut to form a wave cut (abrasion) notch. As the notch gets larger the cliff above becomes increasingly unsupported and in time collapses ( often by a mass movement process!) As this process continues the cliff will slowly retreat. The flat land left at the foot of the cliff is called a wave cut platform

15. LITHOSPHERE CORE COASTLINES 15 Cliffs and Wave Cut Platforms

16. LITHOSPHERE CORE COASTLINES 16 Durdle Door arch behind a Wave Cut Platform at low tide.

17. LITHOSPHERE CORE COASTLINES 17 Sea Inlet near Noss Point Caused by hydraulic action at a weakness in the rock.

18. LITHOSPHERE CORE COASTLINES 18 Sea Inlet At Duncansby Head

19. LITHOSPHERE CORE COASTLINES 19 The headland diagram- You MUST LEARN THIS!

20. LITHOSPHERE CORE COASTLINES

21. LITHOSPHERE CORE COASTLINES

22. LITHOSPHERE CORE COASTLINES HEADLANDCAVECAVE & ARCH ARCH & STACK STACK & STUMP

23. LITHOSPHERE CORE COASTLINES 23 Smoo Cave near Durness

24. LITHOSPHERE CORE COASTLINES 24 A Blowhole or ‘gloup’ may form if the erosion at the back of the cave breaks through the roof to the top of the cliff. This usually happens at high tide in stormy weather.

25. LITHOSPHERE CORE COASTLINES 25 An arch forms when the sea breaks through to the other side of the headland.

26. LITHOSPHERE CORE COASTLINES 26 Durdle Door.

27. LITHOSPHERE CORE COASTLINES 27 The Pinnacles at Ballard Point- stacks

28. LITHOSPHERE CORE COASTLINES 28 Old Harry stack, Dorset Coast Old Harry used to have a ‘wife’, but she has almost disappeared as a stump!

29. LITHOSPHERE CORE COASTLINES 29 Coves are a special feature and we will learn about them by looking at a case study of Lulworth Cove.

30. LITHOSPHERE CORE COASTLINES 30 Lulworth Cove was formed by differential erosion. The next slides will explain how this happened.

31. LITHOSPHERE CORE COASTLINES 31 The hard rock at the coast has been breached. The sea can now get in to erode the softer rock behind, creating the cove. The second layer of hard rock stops the cove growing much larger. soft hard The geology of Lulworth Cove Copy the diagram and explanation.

32. LITHOSPHERE CORE COASTLINES 32 Chalk Sandstones and clays Limestone

33. LITHOSPHERE CORE COASTLINES 33

34. LITHOSPHERE CORE COASTLINES 34 When you are revising this topic, for each feature mentioned, look back through your unit booklets and this presentation. You are looking for named examples of as many features as possible.

35. LITHOSPHERE CORE COASTLINES 35 You have now completed the erosion section of this unit. You should be familiar with the following terms and be able to define and use them in your answers. Copy this list. PROCESSES SOLUTION WAVE POUNDING ABRASION ATTRITION HYDRAULIC ACTION WATER-LAYER WEATHERING FEATURES BLOWHOLE ARCH NEEDLE CAVE STUMP STACK COVE INLET BAY AND HEADLAND NOTCHES WAVE-CUT PLATFORM RELATED TERMS FETCH STRATIFICATION ROCK ORIENTATION DIFFERENTIAL EROSION END