7. (Ai) Cliff & Shore Platform – Formation
— Initially, when waves repeatedly pound against a rocky
coast, it weakens the rocks causing lines of weakness to
form in the rock face.
— (a) Over time, the waves
erode the coast to cut a
notch along the lines of
weakness – HOW?
20
8. Recall: coastal erosional processes
— Corrasion /Abrasion*
— The waves throw rock particles at the coast,
eroding the cliff face away.
— Attrition
— Rocks and pebbles collide with each other.
— Solution / Corrosion
— Acids contained in sea water will slowly dissolve rock
minerals.
— Hydraulic action*
— The force of the waves forces rocks apart.
15
9. (Ai) Cliff & Shore Platform – Formation
— (b)Then, the notch may be further eroded and
deepened to form a cave.
— A cave is a hollow
space that is bigger
than a notch.
20
10. (Ai) Cliff & Shore Platform – Formation
20
— (c)The overhanging part of the notch or cave
eventually collapses with repeated pounding of the
waves.
— The part of the coast
that is left forms a
cliff.
11. (Ai) Cliff & Shore Platform – Formation
— (d)As the cliff continues to be eroded by waves, it
retreats inland.
— Over time, a gently
sloping or flat surface
known as a
shore platform
forms at the base of
the cliff.
20
14. INITIAL STAGES:
• Some coasts are made up of alternate bands of rocks with
different resistance to erosion.
• The less resistant rocks (eg. chalk)
erode faster compared to the
more resistant rocks (eg. granite).
(Aii) Headlands and Bays – Formation
22
15. DEVELOPED STAGES:
• The different rates of erosion of the rocks along a coast
produce an uneven coastline.
• Being more susceptible to erosion,
the less resistant areas of rocks
curve inwards as they get eroded
away by the waves à forms bays.
• The areas made up of more
resistant rocks will protrude out
from coastline à forms headlands
which extend into the sea.
(Aii) Headlands and Bays – Formation
16. (Aii) Headlands and Bays
Flamborough Head, on the
Yorkshire Coast of England
20
17. DEVELOPED STAGES:
— When waves approach the coast in a parallel manner, their
energy is concentrated on the headlands because the
waves bend (recall:wave refraction) as they approach the
protruding headlands.
— The bending of the
waves is due to some
waves slowing down
as they reach the
shallower water in
front of the headlands.
(Aii) Headlands and Bays – Formation
22
18. LATER STAGES:
— Over time, with the continuous erosion of the headland
and deposition at the bay, the coastline may straighten.
— Differential rates of erosion between the resistant and
less resistant rocks
will then result in
the formation of
headlands and bays
again.
(Aii) Headlands and Bays – Formation
22
19. (Aii) Headlands and Bays – Main Features
Alternate
bands
Different
rate
of
erosion
Deposition
Refraction
20. Ladram Bay in East Devon, British isles
(Aiii) Caves, Arches and Stacks
21. — Within headlands, some rocks may be less
resistant to erosion than other rocks.
— The less resistant parts will be eroded more
quickly (recall:coastal erosional processes).
(Aiii) Caves, Arches and Stacks 24
22. — (a)Waves attack lines of weaknesses (eg joints
and faults) at the base of the headland and
undercut it.
— This prolonged
undercutting
hollows out
the base area,
forming a cave.
(Aiii) Caves, Arches and Stacks - Formation
24
23. — (b)As caves develop on each side of the
headland, erosion may eventually join caves
together,
forming an
opening at the
base of the
headland called
arch.
(Aiii) Caves, Arches and Stacks - Formation
24
25. — (c) Over time, the roof of the arch may
collapse to form a stack (a pillar of rock in
the sea after the arch collapses).
(Aiii) Caves, Arches and Stacks - Formation
24
27. (Aiii) Caves, Arches and Stacks - Formation
24
— (d)The stack may be further eroded by waves,
causing some portions of it to collapse,
forming stumps.
28. (A) Cliffed Coasts – Recap
Putting all the features and landforms caused by erosion:
(Arch)
(Shore
pla.orm)
Undercut
Collapse
Hollow
out
Wave
erosion
Lines
of
weakness
30. — A beach is a zone of sediment deposition.
— Composition and size of beach materials vary greatly:
— Beaches are usually formed from loose sand, gravel, pebbles,
broken shells and corals, or a mixture of these materials.
— Source of beach materials affects the composition of beach
materials:
— Beach material may come from eroded cliffs, river deposits
and sediments carried by waves.
— The slope of the beach:
— Determined by grain size (finer grain size à gentle gradient;
coarser grains à steeper gradient.)
(Bi) Beaches 25
34. — Beaches are constantly changing as their shapes
and sizes are affected daily by waves, tides and
currents.
— During calm weather, constructive waves can
help to deposit materials on the beach and build it
up further.
— During coastal storms, strong waves
(destructive waves) will remove materials from
the beach, eroding it away.
25(Bi) Beaches
37. (Bii) Spits 28
— A spit is a long, narrow ridge of sand or pebbles
with one end attached to the land.
— It is formed by
longshore
drift.
Golden Horn or Zlatni Rat Beach,
Bol, Brac Island, Croatia
39. (Bii) Spits – Formation 28
1
1. Direction of prevailing
winds blowing at an
angle to the coastline.
40. (Bii) Spits – Formation 28
2
2. Longshore drift moves
materials along the
coastline.
41. (Bii) Spits – Formation 28
3
3. Longshore drift transports
beach materials in same
direction as prevailing
winds.
42. (Bii) Spits – Formation 28
4
4. This deposition will cause
a sand bank to build up,
called a spit.
43. (Bii) Spits – Formation 28
4
4. Overtime, a long, narrow
ridge of sand with one end
attached to main land and
the other extending to the
open sea will be formed.
44. (Bii) Spits – Formation 28
5
5. This leads to further
deposition and causes the
marshland to form.
54. Activity Time!
1. Choose your favorite COASTAL FEATURE / LANDFORM.
2. With your partner, draw a sketch of its formation process.
• What are they key features?
• What might it look like before?
• What coastal processes operated on it?
• What might it look like in the future?
3. After sketching, explain how and why did the landform
transform into what it looks like today.
• Remember the key geographical terms that are used to
explain its formation.
• What other key features/concepts can you bring in?
