1. Earthshapes Unit RIVERS Vincent Raeburn Linlithgow Academy
Malcolm McDonald Bathgate Academy Linlithgow Academy

2. 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

3. How rivers transport Traction Suspension Saltation Solution
Rolling stones along the river bed.( needs lots of energy)
Traction
Suspension
Clay sized particles are carried along by the river flow
river flow
Saltation
Sand sized particles
bounce along the riverbed
Solution
Some minerals are dissolved
by the riverwater

4. River Basin Watershed of River Aye Source of River Aye Tributary
(boundary between basins)
Source of River Aye
Tributary
of River Aye
Confluence
of River Aye
and tributary
Flood plain
Mouth of
River Aye
Estuary of
River Aye
Sea

5. THE RIVER MODEL Source of river Upper Course Middle Course Lower

6. FEATURES OF THE UPPER COURSE
V-SHAPED VALLEYS WITH INTERLOCKING SPURS
WATERFALLS AND RAPIDS
POT HOLES ON RIVER BED

7. Formation of a waterfall
Retreats upstream
Hard rock
Soft rock
Steep sides
( gorge )
Undercutting
erodes the
softer rock
forming an overhang
The overhang
Eventually
collapses
The process
starts again
Vertical erosion
Forms plunge pool
Eroded rock

8. WATERFALL
RETREATS . .
UPSTREAM . .
OVERHANG
PLUNGE
POOL
UNDERCUTTING
OF SOFT ROCK

9. The River Avon has smoothed off parts
of this hard igneous rock. . .
What is this process called?

10. MEANDERS Meanders Flood plain Possible break through point Possible
ox-bow
lake
Most erosion
on the outside
of the bend .. Fastest flow
Flood plain
© Used with the permission of the Geological Survey of Canada, Natural Resources Canada
Available at – Terrain Science Division

11. River bend Fastest current slowest current Bank will collapse Small
cliff
Slip off slope
( river beach )
Deposition of
Sand and shingle
Outer bank
Is undercut
Deepest part
of the river

12. Formation of an ox-bow lake
Most erosion
The river now follows the new route
Eventually during a period of
heavy river flow it cuts through
Some bends get closer
and closer
The meanders change shape
through time
Most deposition
(Slip off slope)
Small river
cliff is formed
© Used with the permission of the Geological Survey of Canada, Natural Resources Canada
Available at – Terrain Science Division
The bends migrate
Sideways leaving deposits on the inside
Of the bend
At the bends the river flows faster
at the outside
The neck gets narrower
and narrower
The old meander
Is left as a small lake
(OX - BOW lake)
The erosion makes the
Meanders more pronounced

13. Want to see that again ?

14. NARROW MEANDER NECK
FUTURE
OX-BOW LAKE

15. River is actually flowing above
The floodplain !!
Gentle valley sides
Levees is often
artificially
strengthened
Flat floodplain
Coarse material
Forms natural
levees
Layers of silt
Deposited during floods

16. River features Slope usually steep quite steep gentle Width narrow
Characteristics
Upper Course
Middle Course
Lower Course
Slope
usually steep
quite steep
gentle
Width
narrow
quite wide
wide
Depth
shallow
quite deep
deep
Straightness
winding
meandering
big meanders
Load
some
lots
little
small+
rounded
medium/small
rounded
Type of load
large/small
angular
Main work
erosion
transportation
Transportation
transportation
deposition
Valley width
narrow
quite wide
wide

17. 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