Marine processes

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Starter

Waves can have huge amounts of energy...

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Activities

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Types of waves

Constructive Waves

  • Associated with calm weather.
  • Are less powerful waves.
  • Break on the shore and tend to deposit material.
  • Are responsible for transporting material.
  • Swash is stronger than the backwash.

Destructive Waves

  • Associated with storm conditions.
  • Are created when the wave energy is high and there is a large fetch.
  • Tend to remove material from the coast and are therefore associated with erosion.
  • Backwash is stronger than the swash.
  1. Make notes on the differences between constructive and destructive waves.
  2. Define the following terms:
    • Swash
    • Backwash
  3. Which of the following marine erosion is the odd one out: abrasion, attrition, solution, hydraulic action and why?
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Components of waves

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Marine transport

Diagram to show the principal components involved in the development of a coastal sediment cell
Diagram to show the principal components involved in the development of a coastal sediment cell
  1. Describe the inputs of sediment into coastal sediment cell.
  2. Describe the outputs of sediment into coastal sediment cell.
  1. Describe the process of longshore drift.
  2. In the process of longshore drift why does beach material get washed up the beach at an angle?
  3. In the process of longshore drift why does beach material wash back down the beach at right angles to the coastline?
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Resorting (Grading) of beach materials

Selwick Bay - Beach material

The action of waves constantly moves and sorts different sized material beach material.

On some beaches, the sediment is sorted alongshore so that the coarsest material is located at the position with the greatest wave energy and the smallest in the lowest energy environment.

The action of longshore drift can also sort grade beach material, due to the amount of energy required to move sediments. Larger particles will need more energy and therefore move at a slower pace.

Sediment also moves up and down the beaches. In these circumstances, there is little movement of water alongshore and most waves wash up and run back down the beach slope (as 'backwash'). The high sorting of beaches is due to the differentiating effects of swash and backwash. Coarser material is moved up the beach by strong swash, but the backwash is weakened by percolation. The coarsest materials tend to be found at the limit of wave action, while the finer ones are moved in to the lower energy zones offshore.

  1. Describe three ways in which beach material can be sorted by wave processes.
Review

Review

How confident are you about your ability to do the following things ...

  • Demonstrate an understanding of wave processes in eroding a coastline
  • Demonstrate an understanding of wave processes in re-sorting materials
  • Demonstrate an understanding of wave processes in depositing materials
  • Understand the different types of waves
  • Explain corrasion, hydraulic action, corrosion and attrition
  • Explain the process of longshore drift