The document discusses various coastal landforms formed by erosion and deposition processes along shorelines. It describes how cliffs and wave-cut platforms form through wave erosion and undercutting of rock faces. It also explains how alternating hard and soft rock layers lead to the development of headlands and bays, and how wave refraction directs more energy towards headlands. Finally, it outlines how beaches, spits, and tombolos are depositional landforms that form through transport and accumulation of sediments by waves and currents.

1. Coastal Landforms
Erosional Landforms
Cliffs and Wave-cut platforms
• A cliff is a steep rock face. Some tilt forward while
others tilt backwards.
• They are produced by waves undercutting a steep
rocky coast.

2. Coastal Landforms
Erosional Landforms
Cliffs and Wave-cut platforms
• Hydraulic action and
abrasion erode cracks on
a rock surface.
• These cracks may enlarge
to produce a notch,
which may further
deepen inwards to
produce a cave.

3. Coastal Landforms
Erosional Landforms
Cliffs and Wave-cut platforms
• Further undercutting by
waves will cause the roof
of the cave to collapse.
• Undercutting by waves at
the base forms an
overhanging cliff.

4. Coastal Landforms
Erosional Landforms
Cliffs and Wave-cut platforms
• This overhanging cliff will collapse and materials
will be deposited at the foot of the cliff.
• Some of these materials may be washed out into
the sea and picked up by waves that throw them
against the base of the cliff, causing further
erosion.

5. Coastal Landforms
Erosional Landforms
Headlands and bays
• Along coasts with alternate
strips of resistant hard
rocks and less resistant soft
rocks arranged at right
angles to the coast, the
soft rocks are eroded faster
than hard rocks.
• This forms indented coasts
with headlands and bays.

6. Coastal Landforms
Erosional Landforms
Headlands and bays
• When softer rocks are eroded away, bays are formed.
The remaining hard rocks are headlands.
• Waves usually approach the shore at a right angle.
• As they approach an indented shore, they refract.
Consequently, they move parallel to the shore.
• This is called wave refraction, caused by the uneven
depth of the seafloor.
• As they bend energy is unevenly distributed along the
shoreline.

7. Coastal Landforms
Erosional Landforms
Headlands and bays
• The part of the waves
nearer to the shore
touches the seafloor
first.
• It slows down due to
friction with the seafloor
while the rest of the
waves move at full
speed.

8. Coastal Landforms
Erosional Landforms
Headlands and bays
• As a result of wave refraction, waves approach the
shallow sea in front of the headland first before they
reach the adjacent bays.
• Wave energy strikes at the headland rather than the
bay and erosion occurs.
• Along the bays, waves are diverged and weak.
• Deposition of sediments take place along the bays
over time, forming a sandy beach.

9. Coastal Landforms
Erosional Landforms
Headlands and bays
• Wave refraction determines when and where
erosion, transportation and deposition takes place.

10. Coastal Landforms
Depositional Landforms
Beaches
• It is a zone of deposition along the coast, usually
consisting of sandy materials.

11. Coastal Landforms
Depositional Landforms
Beaches
• It can also be formed from broken coral pieces, small
stones called pebbles and blackish volcanic sand.
• The size and composition of the materials vary
greatly and change over time according to weather
conditions, wind direction and ocean currents.

12. Coastal Landforms
Depositional Landforms
Beaches
• Usually the waves and
wind will sort out
materials on the beach,
usually with finer
materials nearer the sea
and coarser materials
further inland.

13. Coastal Landforms
Depositional Landforms
Spits and Tombolos
• Longshore drift transports
materials along a coast.
• If there is a certain change
in the direction of the
coast, the drift will
continue to transport
materials in the original
direction into the sea.
• When materials enter the
sea, deposition occurs.

14. Coastal Landforms
Depositional Landforms
Spits and Tombolos
• After some time, materials
accumulate above water
surface, forming a spit.
• If there is an island near
the mainland where the
spit is formed, it may join
the island to the mainland
forming a tombolo.

15. Homework
Using well-labelled diagrams, explain the formation of:
a) a cliff
b) a wave-cut platform
c) headlands and bays
d) a beach
e) a spit and a tombolo