Title: HIGHER GEOGRAPHY
1BEACHES
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
2The 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.
3Recap
- 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
4LONGSHORE DRIFT
Splash zone
Backwash direction
Swash direction
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 process?Longshore drift
5Q1. 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.
6Q3.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.
7 8Types 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.
9- 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.
10(No Transcript)
11Sand 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.
12BBC 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
13Salt 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
14Sand dunes and salt marsh
15Re-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.
16Re-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.
17Re-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.
18Re-cap of coast so far
- Q5) explain how a blowhole is formed.
- Q6) explain how a Geo is formed.
19Re-cap of coast so far
- Q7) explain how a Saltmarshes are formed.
- Q8) explain how a Geo is formed.
20ORDNANCE SURVEY MAPWORK
7
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 !!
21As 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!
22You 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 BAY BAR SPIT TOMBOLO HEADLAND SORTING GROYNE
LONGSHORE DRIFT LAGOON SALT MARSH SHINGLE SWASH BA
CKWASH ON-SHORE WIND