Vincent Raeburn Linlithgow Academy
Malcolm McDonald Bathgate Academy Linlithgow A
How rivers erode
 HYDRAULIC ACTION The force of the
water weakens and breaks up the rocks
 ABRASION The material carried in the
river wears away the river bed
 ATTRITION As the pebbles carried by
the river crash into each other,they
become smaller and rounder
 SOLUTION
The water in the river
dissolves the minerals in the rocks
How rivers transport
Traction
Suspension
Rolling stones along the river
bed.( needs lots of energy)
Clay sized particles are carried
along by the river flow
river flow
Saltation
Solution
Some minerals are dissolved
Sand sized particles
bounce along the riverbed by the riverwater
River Basin
Source of River Aye
Watershed of River Aye
(boundary between basins)
Tributary
of River Aye
Confluence
of River Aye
and tributary
Estuary of
River Aye
Flood plain
Mouth of
River Aye
Sea
Source
of river
Upper
Course
Middle
Course
Lower
Course
FEATURES OF THE UPPER COURSE
V-SHAPED VALLEYS WITH
INTERLOCKING SPURS
WATERFALLS AND RAPIDS
POT HOLES ON RIVER BED
Formation of a waterfall
Waterfall
Retreats upstream
Hard rock
Soft rock
Undercutting
The
overhang
The
erodesprocess
the
Eventually
Vertical
erosion
startsrock
again
softer
collapses
Forms plunge
pool
forming
an overhang
Steep sides
( gorge )
Eroded rock
WATERFALL
RETREATS . UPSTREAM
.
. .
OVERHANG
UNDERCUTTING
OF SOFT ROCK
PLUNGE
POOL
The River Avon has smoothed off parts
of this hard igneous rock. . .
What is this process called?
MEANDERS
Meanders
Possible break
through point
Most erosion
on the outside
of the bend .. Fastest flow
Possible
ox-bow
lake
Flood plain
© Used with the permission of the Geological Survey of Canada, Natural Resources Canada
Available at
http://sts.gsc.nrcan.gc.ca – Terrain Science Division
River bend
Fastest current
slowest current
Bank will
collapse
Small
river
cliff
Outer bank
Is undercut
Deepest part
of the river
Slip off slope
( river beach )
Deposition of
Sand and shingle
Formation of an ox-bow lake
The Some
river
Eventually
now
follows
during
the
a period
new route
ofMost erosion
bends
get
closer
Theheavy
meanders
change
shapethrough
river
flow
it
cuts
and closer
Most deposition
through
time
Small river
(Slip off slope)
cliff is formed
© Used with the permission of the
Geological Survey of Canada, Natural
Resources Canada
Available at
http://sts.gsc.nrcan.gc.ca –
Terrain Science Division
The bends migrate
At the bends the
Sideways leaving
river flows faster
The
neck gets narrower
The
old
meander
deposits on the inside
at the outside
The
erosion
the
andasnarrower
Is left
a small lake Of the makes
bend
Meanders
more
pronounced
(OX - BOW lake)
Want to see that again ?
NARROW MEANDER NECK
FUTURE
OX-BOW LAKE
Gentle valley sides
River is actually flowing above
The floodplain !!
Flat floodplain
Layers of silt
Deposited during floods
Levees is often
artificially
strengthened
Coarse material
Forms natural
levees
Characteristics
Middle Course
Lower Course
quite steep
quite wide
gentle
wide
shallow
quite deep
deep
Straightness winding
Load
little
meandering
Type of load large/small
angular
medium/small
rounded
Slope
Width
Depth
Main work
Valley width
Upper Course
usually steep
narrow
some
big meanders
lots
small+
rounded
erosion
Transportation transportation
transportation
deposition
narrow
quite wide
wide
tributaries
V shaped valley
Steep
Valley
sides
meander
ox-bow
lake
Flood
plain
Reproduced with kind permission of Ordnance Survey © Crown Copyright NC/03/18990