HIGHER GEOGRAPHY

1
MARINE DEPOSITION PROCESSES.
The material eroded from the features discussed
in slideshow 1 provides a lot of the material for
the features in this slideshow! These slide-shows
are all on the Prepwork folder if you wish to
copy any notes from them we will not be stopping
in class for you to do this.
Copy the text from the next two slides.
2
BEACHES
Beaches are a buffer zone between the waves and
the coast. They usually lie between high and low
tide marks, but storms can throw material up
beyond high tide marks.
3
The main activity of constructive waves is to
deposit pebbles, sand and mud to form a beach.
The sea sorts this material into different sizes
according to its weight as it moves it about in
the water.
4
LONGSHORE DRIFT
Splash zone
Backwash direction
Swash direction
High tide mark
Intertidal zone
Low tide mark
On-shore winds make waves approach at an angle
( swash), but they go back down ( backwash) at
right angles to the beach. What is the result of
this process?
5
Read factzone 5 of the booklet. Make sure that
you can explain how longshore drift works and
draw a labelled diagram. Answer the questions on
the next slide in sentences, as usual.
6
Q1. Define the terms swash and backwash. A. The
swash is the wave motion up the beach away from
the sea, and the backwash is the wave motion down
to the sea again. Q2. Why do the waves not
travel up and down at the same angle? A. An
off-shore wind or sea current forces the waves
onto the beach at an angle. Gravity makes them
return at right angles to the sea.
7
Q3.What is the overall result of this action? A.
The material moves along the coastline in the
direction of the wind/ current. Q4.How do people
attempt to stop this movement? A.Structures
called groynes are built at intervals along the
beach to stop material travelling all along the
coast. The material is periodically moved back to
where it came from, usually by bulldozers.
8

• How do Sand Spits form?
• Longshore drift moves large amounts of material
  along the beach until there is a sudden change in
  the direction of the coastline. The sand keeps on
  moving in the original direction, even though
  there is not a coastline to follow.
• The sea has to be relatively shallow and
  sheltered allowing the accumulation of sand
  usually beyond a headland.
• Sometimes a curve develops if the on- shore wind
  changes direction.
• Spits can become permanent if the prevailing wind
  picks up sand and blows it inland forming sand
  dunes.

Copy this text.
9
Hurst Spit in Hampshire is an example that you
can quote in the exam.
10
On page 289 of WIDER WORLD there is a diagram to
copy fig 16.25
HURST SPIT, HAMPSHIRE
11

• How Do Bars and Lagoons form?
• A bar is a barrier of sand stretching right
  across a sheltered bay.
• It usually stretches across the bay due to the
  absence of any large river that might wash it
  away.
• It can cut off a lagoon to the landward side.
• A lagoon is a body of brackish water- part salty,
  and part fresh. It often supports specialised
  plants and animals, and is protected as a nature
  reserve.

Copy this text.
12
This spit will become a bar if it reaches the
other side of the estuary. Can you work out the
direction of longshore drift?
13
If a bar links up with an off-shore island, it
creates a tombolo. Chesil Beach- one of the most
famous bars in the UK has a tombolo called
Portland Bill.
bar
tombolo
Chesil beach from Portland Bill the shingle is
29kms long.
14
ORDNANCE SURVEY MAPWORK
9
You need to be able to recognise coastal
deposition landforms from a map. To practice
this skill, take a copy of the question sheet and
the two O.S. maps and tackle the questions. THEY
ARE NOT ALL EASY !!
15
As you go through the next revision slide, for
each feature mentioned, look back through your
textbooks and this presentation. You are looking
for named examples of as many features as
possible.
Perhaps you could work in pairs to do this task!
16
You have now completed the deposition section of
this unit. You should be familiar with the
following terms and be able to define and use
them in your answers.
LONGSHORE DRIFT LAGOON SALT MARSH SHINGLE SWASH BA
CKWASH ON-SHORE WIND
BEACH BAY BAR SPIT TOMBOLO HEADLAND SORTING GROYNE

17
REVISION TIME ! Erosion and deposition features
Now watch the video- tape 36 number 3 stop
after the narrator starts to talk about human
intervention in coastal features- you will see
the rest of the video when we learn about the
case studies of coastal management in the Rural
Land Resources Application
END