This document discusses coastal sediment processes and sediment cells. It defines sediment cells as discrete areas of coastline where sediment movement is self-contained. Sediment sources include erosion of cliffs, material from the seabed brought in by currents, and rivers transporting sediment downstream. Sediment is either stored in depositional landforms or transported through the system. Waves, currents, tides, and wind move sediment from source areas and deposit it in coastal landforms like beaches and dunes. The document outlines different coastal erosion processes and types of mass movement. Learning objectives are to understand wave refraction, sediment cells, coastal erosion processes, and mass movement concepts.

1. Sediment Cells and
Sources
AS Geography

2. Learning Objectives
• Demonstrate an understanding of wave
refraction
• Develop an awareness of littoral cells and
different types of sediment
• Demonstrate a knowledge of coastal
processes including erosion
• Evaluate the concepts behind mass
movement

3. Wave Refraction
• As waves leave deep water they become
affected by frictional drag as they come
into contact with the seabed

4. Sediment Sources
• Erosion of the cliffs can provide direct
sediment input
• currents bring in material from the sea bed
• Rivers bring sediment downstream
• There are several methods by which
sediment can reach the sea

5. What happens to sediment
• Sediment is either stored as a depositional
landform
• As a nearshore feature such a bank or
offshore bar.
• Alternatively it is transported as a
throughput and become outputs from the
system being deposited either in deeper
water or away from the coastal area in
question.

6. Types of Sediment
• Clastic and Biogenic sediment
• Clastic sediments are from rock
weathering and erosion
• Biogenic sediments are the shells and
skeletons of marine organisms

7. Sediment Transport and
Deposition
• What do you think is the main agent of
moving sediment and depositation?
• Waves, currents, tides and wind move
sediment from source areas and deposit it
in the form of coastal land forms
• These exist in a state of “Dynamic
Equilibrium”

8. Sediment Cells/ Littoral Cells
• These depositional landforms (such as
beaches, sand dunes, salt marshes and
mudflats) act as a dynamic sediment store
and sediments are transported onshore,
offshore, and alongshore to create them.
• These stores in turn provide sediment for
stores further down the coast.
• The next slide explains this

10. Sediment Cells of the UK

11. Definitions
• The movement of sand and shingle in the nearshore zone
by longshore drift (littoral drift) has been found to occur in
discrete, functionally separate sediment cells.
• There are 11around England and Wales. Smaller ones are
within these.
• The main cells are defined as a length of coastline and its
associated nearshore area within which the movement of
coarse sediment (sand and shingle) is largely self
contained.
• Interruptions to movement of sand and shingle within one
cell should not affect beaches in an adjacent sediment Cell

12. Transport
• As the particles are moved they become
rounded by Attrition.
• Larger sediment is deposited during high
energy and form beaches whilst some are
also carried in suspension in areas of
reduced energy
• Adjustments to these dynamic
environments happen continuously to
maintain the flux

13. Coastal Processes
• Now for the fun bit
• Coastlines differ due to differing erosion
• Coastal Erosion is the wearing away of the
land by the sea.
• Different types of rocks wear away at
different speeds and in different ways.

14. Types of erosion
• Hydraulic Action. This is the force of
water hitting the cliff and squeezing air into
the cracks in the rock
• Abrasion. This is the force of the bits of
rock carried in the water blasting into the
cliff.
• Attrition. This is the process of rocks
hitting each other and breaking into
smaller rocks
• Corrosion. This is a chemical reaction
between the sea water and the minerals in
the rocks

15. The secret art
of Coastal kung fu!
• Hydraulic Action: make punching movements with hand-
demonstrates force of water hitting cliff.
• Abrasion: make a throwing gesture with hands like you are
throwing dealing cards very rapidly
• Attrition: make 2 fists, and then bring them towards each
other, hitting each other, then open hand to resemble a stone
breaking.
• Corrosion: have arms out stretched in front of you, waving
fingers, and moving arms downwards. Sound effect of
something dissolving is needed.
• Solution: Put arms out in front of you waving fingers and
moving down.

16. Please Don’t be embarrassed
• Oh OK be embarrassed then
• Here we go:

17. Mass Movement
• Exposed weathered rocks are often
susceptible to mass movement

18. Soil Creep
• Slow less than 1cm a year
• Caused by raindrop impacts
• Wet periods add moisture to soil which
swells and expands then falls down slope
• Freeze thaw

19. Solifluction
• Occurs mainly in colder areas, where freeze and then thaw
creates movement due to lack of percolation

20. Earth flows and Mudflows, slides
slumps and Rockfalls
• Faster movements
• Occur on steep slopes
• Found often on unconsolidated slopes
• Can be large or small

21. Other Mass Movement Reasons
• Students are to write short paragraphs on
the following separate into physical and
human causes
• Runoff
• Marine Erosion
• Waves and Beaches
• Geology
• Human Activity
• Sea walls and Coastal Defences
• Land reclamation
• Development

22. Learning Objectives
 Demonstrate an understanding of wave
refraction
 Develop an awareness of littoral cells and
different types of sediment
 Demonstrate a knowledge of coastal
processes including erosion
 Evaluate the concepts behind mass
movement