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Geography - River landforms - Coggle Diagram
Geography - River landforms
Erosional (Upper)
V-shaped valley
narrow
steep-sided
vertical erosion
hydraulic action
abrasion
Freeze-thaw weathering
Interlocking Spurs
vertical erosion
V-shaped valley
low energy water
winds around resistant rock
not strong
Waterfall
River flows over area of hard rock and soft rock
Soft erodes quicker
over time undercuts hard rock
overhang
hydraulic action
abrasion
‘step’
Plunge pool
increased velocity erodes plunge pool
force of falling water
Turbulent velocity
Overhang collapses
gravity
collapsed rock erodes plunge pool
deepens
Undercutting continues
Waterfall retreats upstream
Gorge
waterfall retreats
leaves narrow, steep valley
high valley sides
Fast flowing water
boulders in river bed
Erosional and Depositional
Meander
Wide bend in a river
Formation
Water flows at different speeds in river
Water fastest on outside bend
Thalweg
More erosion (Lateral)
hydraulic action
abrasion
Bank is undercut
River cliff
Pool will form
area of deeper water
Water slowest on inside bend
Less energy
Deposits material
Slip-off slope
Riffle
shallow
turbulent
fast flowing
Over time
Become larger
Ox Bow Lake
Meanders get larger over time
Erosion causes outside bend to get closer
Neck narrows
completely broken through
straighter channel
Most efficient route
meander is stationary
Deposition cuts off meander
Ox bow Lake
hydraulic action and abrasion
Depositional (Lower)
Floodplain
wide flat area of marshy land
either side of a river
Made of
alluvium
fine sediment
silt
deposited by river when it floods
Used for
farming
very fertile soil
Formation
River flood
slows down
loses energy
Deposits material
heaviest first
sand, silts, clays deposited next
then lightest clays and silts
Builds up floodplain
Levee
Natural embankment alongside river
Formation
River flood
Heaviest material deposited closest to channel
Then finer silt and mud
Estuary
Where river meets the sea
Tidal water
river level rises and falls
Deposition
disrupted river flow
Mudflats / Salt marshes
permanent habitat
Transitional zone
Identifying
Contour Lines
height
numbers
steepness
close together lines