2.8. Landforms of deposition (sand dunes)

Question 1

What does sand dune formation need?

Answer 1

• large quantities of sand from constructive waves
• a large tidal range so sand has time to dry
• strong winds that blow dry sand to the beach of beach

Question 2

Where do sand dunes develop?

Answer 2

Where sand is trapped by debris at the back of the beach

Question 3

How do sand dunes form?

Answer 3

• Sand dunes form when sand accumulates around an obstruction on a beach, such as a fence line
• the first plants to grow on embryo dunes and pioneer colonising species such as couch grass or lime grass with long roots which stabilise the sand
• the foredune is stabilised further by xerophytes (plants that can survive with little water) such as marram grass
• the fixed and mature dunes have a high humus content as plants die and break down into the soil and have a large variety of plants

Question 4

What happens to pH as sand dunes develop?

Answer 4

It decreases

Question 5

What happens to humus content as sand dunes develop?

Answer 5

Humus content increases as there is more vegetation

Question 6

What happens to stability as sand dunes develop?

Answer 6

Dunes becomes more stable

Question 7

What are the stages of dunes?

Answer 7

• embryo dunes
• fore dunes-> initially yellow but darken to grey as decaying plants add humus
• yellow dunes
• grey dunes
• dune slack
• mature dunes