CONTENTS

1
CONTENTS
Slide-show 1-Coastlines of erosion Slide-show
2-Coastlines of deposition Slide-show
3-Coastlines of changing sea level
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MARINE EROSION PROCESSES.
Read the course booklet, page 11. You will need
to know and be able to explain the four methods
of coastal erosion and two of weathering on the
page. The next few slides illustrate these
processes. 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
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Hydraulic Action
The force of waves hitting a cliff (or sea wall)
compresses water and air into cracks and joints.
This increase in pressure may lead to cracks
widening and pieces of rock breaking off.
There is no separate picture for wave pounding!
4
Abrasion
Rock fragments may be picked up by waves and
thrown against the rock face of cliffs by
subsequent waves. Sometimes the softer strata
are abraded more than the harder ones, giving a
striped appearance. Abrasion is most effective at
the base of cliffs.
5
Wave attrition
Rock fragments are worn down into smaller and
more rounded pieces. Currents and tidal
movements cause the fragments to be swirled
around and to grind against each other. This
type of erosion produces pebble beaches.
6
Water- layer weathering
Alternative wetting and drying -as happens with
the rise and fall of the tides -can disintegrate
porous or coarser rock layers. Salt crystals
growing in rock spaces can do the same thing.
7
Corrosion (solution)
Salts and acids in sea water can react with rocks
, slowly dissolving them away.
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TEST YOURSELF!
Match the processes with the description on the
next slide by writing them out in your jotter.
Write these heads first, leaving a space of
about three lines for each,to write in the
tails.
heads
Hydraulic pressure is- Corrasion is- Attrition
is- Corrosion/solution is-
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-the chemical weathering of the cliff when salts
and weak acids dissolve rock minerals. -the sheer
force of the waves as they crash into a cliff
explode, compress the air, and cause the face to
break up. -the sandpaper effect when waves, armed
with rocks and pebbles, rub away the base of the
cliff. -rocks and pebbles rub against each other
on beaches forming smaller and smaller particles.
tails
10
Rates of erosion depend on many factors
(Copy this note into your jotters. Discuss the
factors in class.)

• Waves strength, frequency, height
• Weather frequency of storm conditions
• Geology of the coastline
• -type of rock
• -orientation of stratification

11
The FETCH is the distance travelled by waves from
one shore to another. The waves hitting the
southwest coast of England have a fetch of about
ten thousand miles!
Copy this note!
12

• There are eight erosion-related features you need
  to learn up.
• You need to be able to -
• Describe them using their proper terms
• Explain IN DETAIL how they form
• Draw simple LABELLED SKETCHES of them
• Give EXAMPLES of them in the UK.

BAY AND HEADLAND
CAVE AND BLOWHOLE
STACK
STUMP
ABRASION NOTCHES
ARCH
NEEDLE
WAVE-CUT PLATFORM
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Many erosion features are a result of rocks of
varying hardness occurring beside/below each
other. The DIFFERENTIAL EROSION between them
creates the landform. (Note that mass movements
may also be triggered as a result. )
Read about them on pages 12-13 of the booklet,
and answer the questions to help focus your
attention on the most important factors.
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Q1. What two properties of a headland tell us
that the rock is hard? A. It juts out into the
sea and is high ground. Q2. What two properties
of a bay tell us that the rock is soft? A. It
eats back into the land and is lower ground. Q3.
On a new cliff coast, what is the first feature
caused by erosion? A. Abrasion notches are
created initially.
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Q4.Cliff retreat creates which feature all along
the coast? A. It creates a wave-cut
platform. Q5.Why is this only exposed at low
tide? A. Erosion only happens between high and
low tide marks, and no erosion takes place below
LTM. The top of the eroded cliff is the WCP,
seen only when the tide is lowest.
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Headland erosion near Noss Point CaithnessThe
sea is eroding this headland back leaving a
wave-cut platform below the waves.

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How Are Wave Cut Platforms Formed? (Copy this
note into your jotter.)

• Erosion is greatest when large waves actually
  break against the foot of a cliff.
• The foot of the cliff is undercut to form a wave
  cut ( abrasion) notch.
• As the notch gets larger the cliff above becomes
  increasingly unsupported and in time collapses (
  often by a mass movement process!)
• As this process continues the cliff will slowly
  retreat.
• The flat land left at the foot of the cliff is
  called a wave cut platform

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See how the base of this cliff is being broken up
by the attrition of the cobbles- and litter- at
its high tide mark.
Abrasion notches
Note the softer layer of shale at the cliff foot!
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Cliffs and Wave Cut Platforms
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There is a copy of this diagram to stick into
your jotters. Add in the labels to your copy.
3
21
Sea Inlet near Noss Point Caused by hydraulic
action at a weakness in the rock.
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Sea Inlet At Duncansby Head
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There is a copy of this diagram to stick into
your jotters. Copy the text onto your copy of
this diagram.
Note- for a cave to occur, there must be an area
of weakness in the cliff face.
4
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Smoo Cave near Durness
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A Blowhole or gloup may form if the erosion
at the back of the cave breaks through the roof
to the top of the cliff.This usually happens
at hightide in stormy weather. Copy this
note!
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There is a copy of this diagram to stick into
your jotters. Copy the text onto your copy of
this diagram.
5
notches
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An arch forms when the sea breaks through to the
other side of the headland.
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Natural Arch
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Close up of Duncansby Stacks
and Stump
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Stack At Sandwood Bay
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MINI-HOMEWORK EXERCISE
Take a copy of the homework exercise. It is a
feature- identification and explanation
task. Answer it on A4 sized paper, and hand it in
for marking. Please write it in black/blue ink
or word- process it, proof-read it, and put your
name on it!
6
Suggested answers -available later!
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Coves are a special feature and we will learn
about them by looking at a case study of Lulworth
Cove.
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Lulworth Cove was formed by differential erosion.
The next slides will explain how this happened.
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Copy the diagram and explanation.
The geology of Lulworth Cove
The hard rock at the coast has been breached.
The sea can now get in to erode the softer rock
behind, creating the cove. The second layer of
hard rock stops the cove growing much larger.
hard
soft
You will learn the names of the rock types in the
Case Study unit- Rural Land Resources.
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Click on the hyperlink to see the video clip
about Lulworth cove. Add to your notes to make
sure that you can answer a question about this
feature in an exam.
HYPERLINK
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ORDNANCE SURVEY MAPWORK
8
You need to be able to recognise coastal erosion
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 !!
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As you go through the next (revision) slide, for
each feature mentioned, look back through your
unit booklets 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!
THEN PLAY THE COASTLINE DOMINOES GAME!
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You have now completed the erosion section of
this unit. You should be familiar with the
following terms and be able to define and use
them in your answers. Copy this list.
PROCESSES SOLUTION WAVE POUNDING ABRASION ATTRITIO
N HYDRAULIC ACTION WATER-LAYER WEATHERING
FEATURES BLOWHOLE ARCH NEEDLE CAVE STUMP
STACK COVE INLET BAY AND
HEADLAND NOTCHES WAVE-CUT PLATFORM
RELATED TERMS FETCH STRATIFICATION ROCK
ORIENTATION DIFFERENTIAL EROSION
END