Transcript HIGHER GEOGRAPHY

COASTLINES
LITHOSPHERE CORE
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.
Origin of sand
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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.
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Recap
Watch the clip and take notes on
longshore drift and the formation
of the features shown.
BBC - Learning Zone Class Clips Depositional coastlines - Geography
Video
COASTLINES
LITHOSPHERE CORE
LONGSHORE DRIFT
Swash direction
Backwash
direction
Splash
zone
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
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process?Longshore drift
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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.
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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.
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A beach profile
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Types of beaches
Bayhead beach – typically small,
crescent shaped and form when
sediment (usually sand and/or
shingle) accumulates in a bay or
cove between two protective
headlands. Such protection means
little change in input or output of
sediment, so the shape remains.
Lulworth Cove beach is an example.
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Lateral beaches are usually longer,
develop along straight coastlines
and are aligned to the prevailing
winds. There has to be a regular
input of sediment to sustain these
beaches due to longshore drift and
erosion during stormy conditions.
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Sand dunes
Sand dunes are small ridges or hills
of sand found at the top of a
beach, above the usual maximum
reach of the waves. They form
from wind blown sand that is
initially deposited against an
obstruction such as a bush,
driftwood or rock.
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BBC Education Scotland :
CoastliNE : Physical : Features : Coastlines of Deposition
As more sand particles are deposited the
dunes grow in size, forming rows at right
angles to the prevailing wind direction.
If vegetation, such as Marram Grass and
Sand Couch, begins to grow on the dune
its roots will help to bind the sand
together and stabilise the dunes.
BBC - Learning Zone Class Clips - Sand
dune formation and movement - the Dune
of Pilat - Geography Video
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Salt marsh
Salt marshes occur in sheltered water areas,
such as estuaries or behind spits. An estuary is
a wide and shallow area of water where a river
meets the sea; it contains a mixture of fresh
and salt water called brackish, a result of the
twice daily flooding by the tide.
BBC - Learning Zone Class Clips Sands of Forvie - marshes and
mudflats - Geography Video
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Sand dunes and salt marsh
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Re-cap of coast so far:
Q1) define the
following terms:
Swash
Backwash
Hydraulic action
Attrition
Abrasion
Longshore drift
Q2) explain how a
cliff and wave cut
platform is
formed.
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Re-cap of coast so far:
Q3) explain how a
spit, bar and
tobolo are
formed.
Q4) explain how a
cliff and wave cut
platform is
formed.
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Re-cap of coast so far:
Q5) explain how a
cave, arch, stack
and stump are
formed.
Q6) explain how a
headlands and
bays are formed.
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Re-cap of coast so far:
Q5) explain how a
blowhole is
formed.
Q6) explain how a
Geo is formed.
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Re-cap of coast so far:
Q7) explain how a
Saltmarshes are
formed.
Q8) explain how a
Geo is formed.
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ORDNANCE SURVEY MAPWORK
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 !!
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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!
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You have now completed the deposition section .
You should be familiar with the following terms and be
able to define and use them in your answers.
BEACH
LONGSHORE DRIFT
BAY
LAGOON
BAR
SALT MARSH
SPIT
SHINGLE
TOMBOLO
SWASH
HEADLAND
BACKWASH
SORTING
ON-SHORE WIND
GROYNE
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