Transcript SG Rivers - lgsfilehost1

Rivers
Location
Profiles
Processes
Landforms
Main UK Rivers
Thames
Spey
Clyde
Shannon
2
1
Tees
3
Ouse
5
4
Tay
Severn
7
Trent
6
9
8
10
Forth
10
1
4
7
5
9
2
8
6
3
2
5
Source
River Profile
Classic River Profile
Mouth +
Delta
Upper Course
Middle Course
Lower Course
Steep ground
Moderate ground
Gentle ground
Fast flow
Moderate flow
Gentle flow
Erosion
Transportation
Deposition
V-shaped valley
Small meander
Large meander
Waterfall
Small floodplain
Large floodplain
Oxbow lake
River Processes - Transportation
Now Watch The Flash Presentation
On River Transportation
River Processes - Transportation
Process
Description
Saltation
Force of water drags or
rolls rocks along river bed.
Traction
Dissolved material is
carried along in the water.
Suspension
Pebbles are picked up and
bounced along the river
bed by flowing water.
Solution
Very light clays are held up
in the water as it flows.
River Processes - Erosion
Abrasion/Corrasion
Hydraulic Action
Force of water hitting off river banks
causes them to wear down.
Stones carried by river hit into river bed
and bank, eroding & scraping them.
Corrosion
Stones collide into each other knocking
edges off – get smaller and rounder.
Attrition
Rocks dissolve in water e.g. limestone
Landforms Of The Upper Course
V-shaped Valleys
Waterfalls
V-shaped Valley
River Gradient
River Speed
Erosion
1 As the river flows it erodes
downwards initially, due to the great
energy it has. This happens mainly
because of the process of corrasion
(explain in detail for in exam!)
2 The river therefore forms a deep
and steep sided channel. Over time
freeze thaw (again explain)
weathering acts upon the riverbank.
This loosens the rock and soil.
3 As the rock & soil from the river
bank breaks up, it is transported to
the river by to gravity and the
wash effect of rain on the soil.
4 The eroded material that falls into
the river is then transported
downstream by the river and is
deposited on its bed or on a river beach.
2
1
3
4
1
River erodes downwards due to fast flowing water carrying stones.
2
A deep/steep sided channel forms & weathering loosens soil on the banks
3
Rock & soil from river bank breaks up, falls into river due to gravity & rain
4
Eroded material transported downstream and deposited on river bed.
Waterfall
River Gradient
River Speed
Erosion
Waterfall
Now Watch The Two Flash Presentations
On Waterfall Development
Waterfall
Now Watch The Second Flash Presentation
On Waterfall/Gorge Development
A=
Hard Rock
C=
Swirling Rock
F=
Soft Rock
D=
Unsupported Rock
B=
Plunge Pool
E=
Undercutting
Waterfall- Diagram
A
D
C
E
F
B
Waterfall
gorge ~ soft ~ abrasion ~ collapses ~ cliff ~ deeper ~ plunge ~ hard
hard rock, which
A waterfall is formed when a river flows over a layer of ______
is lying over a layer of soft rock. The _____
soft rock erodes more quickly. The
hard rock sticks out forming a _____
cliff in the river, which is a waterfall. The
soft rock at the bottom of the waterfall/cliff is then eroded further to form a
____________
pool. This pool becomes bigger and ____________
as
plunge
deeper
water swirls broken rock around. The hard rock is left unsupported and so
collapses
eventually ______________.
Over a long period of time the waterfall
retreats backwards forming a narrow and steep sided valley called a
gorge You will gain marks for describing either how the erosion occurs
_______.
e.g. Hydraulic Action & __________.
abrasion
Landforms Of The
Middle & Lower Course
Oxbow Lake
Meander
Floodplain
Meanders ~ Bends In Rivers
Meanders
Inner Bend
Slow Flow
Low Energy
Small Rocks
Deposition
Shallow Water
River Beach
Outer Bend
Fast Flow
High Energy
Large Rocks
Erosion
Deep Water
River Cliff
Meander - River bend
Bank will
collapse
Fastest current
slowest current
Small
river
cliff
Outer bank
Is undercut
Deepest part
of the river
( river beach )
Deposition of
Sand and shingle
Meanders - Sequence Exercise
Use your cross section diagram and the words in the same order
as below to write 2 paragraphs explaining how meanders form.
Paragraph 1
Outer bend ~ fast flow ~ high energy ~ large rocks ~ erosion ~ deep water ~
river cliff.
Paragraph 2
Inner bend ~ slow flow ~ low energy ~ small rocks ~ deposition ~ shallow water
~ river beach
Formation of a Meander
Alluvium
erosion
river cliffs
loss of energy
greatest speed
deposition
meanders
The course of a river usually has many bends in it. These are
meanders
greatest speed
called___________.
The _____________of
water is on the
outside of the bend where _________takes
place and the
erosion
river cliffs
channel is worn away to make___________The
water flows
more slowly round the inside of the bend. This causes
loss of energy
deposition
__________________
and _________________
when the river
alluvium
overflows its banks it deposits material called ______________
on the valley floor.
Deposition
Erosion
Meander
Floodplain
Alluvium
Deep Water
Shallow Water
Blue - River
Green Valley
Floor
Brown
Valley
Sides
Oxbow Lakes
2
5
Oxbow Lakes
Oxbow Lakes
Outer Bend
Large Meanders
Neck
An oxbow lake
starts to form when
large meanders
develop close
together (A). As
their outer bends
erode more, there
is only a small
piece of land
remaining between
them, called a neck
(B).
Straighter Channel
Deposition
Old Channel
Eventually the river erodes
through the neck of the
meander and makes a new
straighter river channel
(C). The river now flows
down this channel and
deposits material blocking
up the old channel.
This leaves an
oxbow lake in the
old river channel
and without a supply
of water the lake
can dry up (D). The
lake may reform
when there is heavy
rain or flooding.
Oxbow Lake
Floodplain
Flat Land
Meander Sketch
Floodplain
Flat Land
Floodplain
A
A
F
F
B
E
C
A = Bluff Line
B = Layers Of Alluvium
C = River Bed Level Rises With Increased Deposition
D = Small Particles Deposited Away From River
E = Larger Particles Deposited Close To River
F = Levee
D
Floodplain
A floodplain is a flat area of land either side of a river, which floods
regularly. The widest examples are found in the middle and lower
course.
The river valley gets wider as meanders continue to grow, eroding
back the sides of the valley.
The flat valley that forms is called a floodplain and develops as
alluvium (mud/silt) sediment is deposited after a flood.
The smallest particles are found at the edge of the floodplain and the
largest particles nearest to the river. The largest particles by the river
bank form a mini ridge called a levee, which runs parallel with the
river.