1 / 29

Coastal processes

lixue
Download Presentation

Coastal processes

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

    1. Coastal processes

    2. Types of waves What type of wave is shown in the photograph? Describe the wave shown in the photograph. Draw a diagram of a destructive wave and label its main characteristics.

    3. Types of waves: answers 1 What type of wave is shown in the photograph? This is a constructive wave.

    4. Types of waves: answers Describe the wave shown in the photograph. The swash is more powerful than the backwash. It is on a gently sloping beach. It is long in relation to its height, so it breaks infrequently at a rate of ten or fewer per minute.

    5. Types of waves: answers

    6. Types of weathering 1 Name the main types of weathering. Physical Chemical Biological

    7. Types of weathering 2 Explain the process of physical weathering. Freeze–thaw weathering or frost action occurs when water gets into cracks in rocks. When the temperature falls below freezing, the water expands as it turns into ice. This expansion puts pressure on the rock around it and fragments of rock may break off. This type of weathering is common in highland areas where the temperature is above freezing during the day and below freezing during the night.

    8. Types of weathering 3 Explain the process of chemical weathering. Rainwater contains weak acids that can react with certain rock types. The carbonates in limestone are dissolved by these weak acids and this causes the rock to break up or disintegrate. This can be seen on limestone statues and limestone pavements.

    9. Types of weathering 4 Explain the process of biological weathering. This is the action of plants and animals on the land. Seeds fall into cracks in rocks and will start to grow when moisture is present. The roots of the young plant force their way further into cracks and, in time, can break up the rocks. Burrowing animals, such as rabbits, can also be responsible for the break-up of rocks.

    10. Types of erosion Erosion is the wearing away of rocks by the action of water, wind and ice. Name the three ways that the sea erodes the coast. Explain each type of erosion. See the following slides.

    11. Types of erosion: answers 1 Name the three ways that the sea erodes the coast. Corrasion Corrosion Hydraulic action

    12. Types of erosion: answers 2 Explain each type of erosion. Corrasion — sand and pebbles carried within waves are thrown against the cliff face with considerable force. Corrosion (solution) is a chemical reaction between certain rock types and the salt and other acids in seawater. This is particularly evident on limestone and chalk cliffs. Hydraulic action is the pressure of the water being thrown against the cliffs by the wave. It also includes the compression of air in cracks: as the water gets into cracks in the rock face, it compresses the air in the cracks; this puts even more pressure on the cracks and pieces of rock may break off.

    13. Types of mass movement 1 What is mass movement? Mass movement is when material moves down a slope due to the pull of gravity. There are many types of mass movement, but for the purposes of this topic, only soil creep and slumping will be discussed. 

    14. Types of mass movement 2 Explain the process of soil creep. This is the slowest downhill movement of soil. Gravity pulls the water that is contained in the soil down a slope. The soil moves downhill with the water. As this happens very slowly, it is not possible to see it happening, although the process does happen more quickly after heavy rainfall. The slope may appear rippled (like sheep paths around the hill). These ripples are known as terracettes.

    15. Types of mass movement 3 Explain the process of slumping. Slumping is common on the coast. It is also known as rotational slipping, it involves a large area of land moving down a slope. Because of the nature of the slip, it leaves behind a curved surface. This is common on clay cliffs. During dry weather the clay contracts and cracks; when it rains, the water runs into the cracks and is absorbed until the rock becomes saturated. This weakens the rock and, as a result of the pull of gravity, it slips down the slope on its slip plane.

    18. How does a stack become a stump?

    19. Cliffs and wave-cut platforms 1

    22. The formation of headlands and bays Sketch the diagrams below. Annotate them to explain how headlands and bays form.

    23. The headlands are the more resistant rock and protrude into the sea. Bays are made in a less-resistant rock type, so the erosion rates here are greatest at first. In time, as the sea cuts the bay back, the waves reaching the coast are less powerful because they have to travel over a longer expanse of beach. The headlands further out into the sea now begin to experience the more powerful waves and are eroded at a faster rate than before. The formation of headlands and bays: answer

    24. Longshore drift Copy the diagram below and complete it to explain the process of longshore drift.

    25. Longshore drift: answer

    26. Beaches Describe the characteristic features of a beach.

    27. The formation of a spit

    28. The formation of a spit: answer

    29. The formation of bars

More Related