Erosion is……. the wearing away of materials by one of four processes: <ul><li>Corrosion = chemical reactions of salt water weakening rocks like an acid </li></ul><ul><li>Attrition = Pebbles hitting into each other or into cliffs making rocks break and get smaller and rounder </li></ul><ul><li>Abrasion = ‘sand paper’ effect. Waves throwing small stones and pebbles at cliffs and beaches to smooth the material </li></ul><ul><li>Hydraulic Action = Power of the water forcing its way into cracks and weaknesses in rocks, splitting apart </li></ul>
Exam Q <ul><li>Including keywords where possible, describe and explain how erosion can influence the coast. You may use a diagram. </li></ul><ul><li>[3marks] </li></ul>
Wave erosion is greatest when waves break against the foot of the cliff. With wave energy at a maximum, the waves undercut the foot of the cliff to form a wave cut notch Over time the notch enlarges and the cliff above it cannot be supported and so collapses As this is repeated, the cliff retreats (and often increases in height). The gently sloping expanse of cliff marking the foot of the retreating cliff is known as the Wave cut platform
Does this remind you of anything? Waterfalls and gorges – very similar ideas!
Wave-cut platform –Burgh Island, Devon Wave cut platform Southerndown, South Wales.
How was the arch at Durdle Door, Dorset, formed? Abrasion/Corrasion Hydraulic action Solution/Corrosion Attrition
1. The waves erode FAULTS (cracks) in the headland. 2. The waves eventually erode through the headland to form an ARCH . 3. The arch becomes unsupported and collapses to form a STACK . 4. A STUMP is formed from the collapsed stack. C D B A Match the image with the most appropriate label.
Exam Q <ul><li>How does geology influence the speed of erosion at the coast? </li></ul><ul><li>[2marks] </li></ul>
If you were a wave, and you wanted to grow big and strong so you could knock the UK’s block off, which direction would you come from? Why?
Waves <ul><li>There are two main types of waves: </li></ul><ul><li>Constructive vs Destructive </li></ul>
Exam Q <ul><li>1) Describe and explain how constructive and destructive waves work. Use keywords or examples where possible. [4marks] </li></ul><ul><li>2) Apart from the strength of waves, name and explain another factor that can influence how quickly a coastline erodes? [2marks] </li></ul>
How do waves influence erosion? Longshore drift
Longshore drift…starring Mr R. <ul><li>Longshore drift video explained by Mr Rogers </li></ul>
So, answer the Question: <ul><li>Q: “With the use of a diagram, explain the process and effects of longshore drift, and how it can be managed” </li></ul><ul><li>[6marks] </li></ul>
So, the controlled assessment How does it work?
Example controlled assessments from last year <ul><li>Take a look at what you will be producing </li></ul><ul><li>You will have prep time before the trip, then the trip on 11 th May, then the analysis afterwards </li></ul><ul><li>Key things = keywords, theory, analysis, explanation, evaluation </li></ul>