Negative And Positive Feedback

Question 1

Example of Positive Feedback in relation to Waves

Answer 1

• During a storm, destructive waves remove materials from the beach as they have a stronger backwash than their swash
• This material is deposited to form an offshore bar
• This is an example of positive feedback because the waves remove materials from the beach, creating an offshore bad, so amplifying change and promoting environmental instability

Question 2

Positive Feedback in relation to heavy rainfall

Answer 2

1. A period of high rainfall causes boulder clay cliffs to become saturated
2. Mass movement then occurs as a rotational slump with a toe of material being deposited onto the beach
3. Marine erosion is slowed by the new material on the beach which protects the base of the cliff
   • This is an example of positive feedback because marine erosion is slowed down which amplifys change

Question 3

Example of Positive Feedback in relation to the type of rock on a coastline

Answer 3

1. Cliffs on a hard rock coastline are eroded slowly through marine processes such as abrasion and hydraulic action
2. A band of weaker rock is exposed by erosion. Materials are now removed from the cliff and can be used as abrasive tools
3. The rate of marine erosion increases
   • This is an example of Positive feedback as change is amplified

Question 4

Example of Negative Feedback in relation to Waves

Answer 4

1. Constructive waves build up the beach as they have a more powerful swash than backwash. This means that the beach becomes steeper at some points
2. Steeper beaches then encourage the formation of destructive waves. These waves remove material from the beach as they have a more powerful backwash than swash
   This is an example of negative feedback as change is dampened down/neutralised