coastal systems -depositional landforms (sand dunes)

Question 1

what are sand dunes?

Answer 1

.accumulations of sand that has been blown off the beach by strong onshore winds and shaped into mounds
.same accumulates on the sheltered side

Question 2

where do sand dunes develop?

Answer 2

.may develop immediately behind an active beach zone

Question 3

how are sand dunes formed?

Answer 3

.sand is moved inland by saltation
.when large amounts of sand is exposed at low tide it dries out so the wind from the sea blows the sand onto the beach and a dune begins to form

Question 4

what are embryo dunes?

Answer 4

.the first dunes to develop
.colonised by pioneer plants eg -sea couch and marram grass
.grow upwards to interrupt saltation which traps sand and stabilises the surface
.poineer species add humus to the soil reducing the PH level

Question 5

what type of species exist on embryo dunes?

Answer 5

.xerophytes -drought resistant
.halophytes -salt resistant
.as the conditions here are extremely difficult as they are salty and lack water

Question 6

what are foredunes?

Answer 6

.tend to have a higher dune height beyond the reach of the highest storm tides -5m
.80% covered in vegetation
.ph starts to become less alkaline
.humus content starts to get higher

Question 7

what are yellow dunes?

Answer 7

.higher height of 8-10m
.ph become neutral
.medium level of humus
.allows for marram grass to grow as it has deep roots to reach the water table

Question 8

what are grey dunes?

Answer 8

.development of yellow dunes that turn grey due to high volumes of humus content in the soil
.90% of the dune is colonised
.moisture content is low but fresh
.ph increasingly acidic
.dewberry and heather

Question 9

what are dune slacks?

Answer 9

.depressions between dune ridges
.damp areas where the water table is closest to the surface
.mosses, rushes and willows tend to grow here but it is dependent on local moisture content

Question 10

what do plants do to sand dunes?

Answer 10

.plants stabilise the sand dunes allowing them to mature and reach woodlands

Question 11

what is it called when plants reach woodland?

Answer 11

.climatic climax however if the succession isn’t allowed to reach its natural end point due to human interference it’s called plagioclimax

Question 12

what are sand dunes an example of?

Answer 12

.vegetation succession -a plant community whose structure develops temporally
.succession that occurs on sand is called a psammosere

Question 13

where is an example of sand dunes?

Answer 13

.studland bay on the Dorset coast which lies to the north of swanage bay