Transcript Landforms in the Upper Course

22/09/10
River landforms in the upper course
Aim: To understand how v-shaped
valleys, interlocking spurs and waterfalls
form in the upper section of rivers
Outcome: To draw annotated diagrams
explaining the formation of interlocking
spurs and v-shaped valleys. To order the
sequence of stages involved in waterfall
formation
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Do you know your processes of erosion?
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V-shaped valleys
Task 1.
Describe a V-shaped
valley
A narrow valley with
steep sides and a small
river/tributary running
through it, found in the
upper section of a river
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Why do V-shaped valleys occur?
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Make a copy of the diagrams below showing the formation of V-shaped
valleys. Read the box of annotations below. Choose the correct one for
each diagram and place it in an appropriate place on the diagram with
an arrow.
1.
2.
3.
A. Weathering on the valley sides weakens the soil and under gravity
it moves down hill (mass movement) leaving a more gentle slope
B. Energy in the river is used to erode downwards (vertical erosion)
which deepens the river bed. Processes of abrasion and hydraulic
action occur here.
C. The valley forms a v-shape as it is deepened faster than it is
widened.
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Interlocking Spurs
Task 2.
Describe an
interlocking spur
A sloping ridge that
descends into the valley,
made of more resistant
rock. Spurs on one side
of the valley will interlock
with those from the other
side. Rivers flow around
these.
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Copy the diagram.
Annotate it to
explain how
interlocking spurs
form
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Bands of resistant rock
cross the river’s path
Because the river is slow
(due to friction from the
river bed) it hasn’t got
the energy to erode
through the hard rock,
instead it flows around
them
As the river flows around the
bands of resistant rock, it
leaves behind sloping ridges
called interlocking spurs
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Water falls
Task 3.
Describe a waterfall
A sudden drop in a
river’s route resulting in
water falling vertically
downwards (at higher
speed) until it reaches a
lower level
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Waterfall formation
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Waterfalls
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How does a waterfall form?
Rearrange the stages of formation into the correct order:
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Waterfalls
Draw and annotate a diagram to explain
the formation of a waterfall.
Suggested labels:
1. More resistant
rock
2. Less resistant
rock
3. Plunge Pool
4. Unsupported
rock
5. Fallen rocks
6. Gorge
Your labels should contain detailed explanations!
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The geology of Gulfoss is more complex!
grey basalt
sandstone
mudstone
tillite
grey basalt
conglomerate
plunge
pool
Which of these different rocks do you think is the most resistant?
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What do you know about upland river valleys?
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