9188591
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Mind Map by Mariette Shan, updated more than 1 year ago
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Geography- River and Coasts: Courses
of the River
- Upper Course
- Interlocking spurs
- As the river erodes the landscape in
the upper course, it winds and bends
to avoid areas of hard rock. This
creates interlocking spurs, which look
a bit like the interlocking parts of a zip.
- Rapids
- When a river runs over alternating
layers of hard and soft rock, rapids
and waterfalls may form.
- When a river runs over alternating
layers of hard and soft rock, rapids
and waterfalls may form.
- As the river erodes the landscape in
the upper course, it winds and bends
to avoid areas of hard rock. This
creates interlocking spurs, which look
a bit like the interlocking parts of a zip.
- Waterfalls
- Waterfalls form where a river flows over an area of hard-rock followed by an area of softer rock. The
softer rock is eroded quicker than the hard rock, creating a 'step' in the river. As water goes over the
step it erodes the softer rock more. A steep drop is eventually created, which is called a water fall. The
hard rock is eventually undercut by erosion. It becomes unsupported and collapses. The collapses
rocks are swirled around at the foot of the waterfall where they erode the softer rock by corrasion.
This creates a deep plunge pool.
- Over time, more undercutting causes more collapses. The waterfall will retreat, leaving a steep-sided gorge.
- Over time, more undercutting causes more collapses. The waterfall will retreat, leaving a steep-sided gorge.
- Waterfalls form where a river flows over an area of hard-rock followed by an area of softer rock. The
softer rock is eroded quicker than the hard rock, creating a 'step' in the river. As water goes over the
step it erodes the softer rock more. A steep drop is eventually created, which is called a water fall. The
hard rock is eventually undercut by erosion. It becomes unsupported and collapses. The collapses
rocks are swirled around at the foot of the waterfall where they erode the softer rock by corrasion.
This creates a deep plunge pool.
- Steep gradient
- Large load- boulders.
- Interlocking spurs
- Middle Course
- Meanders
- The force of the water erodes and undercuts
the river bank on the outside of the bend where
water flow has most energy due to decreased
friction. On the inside of the bend, where the
river flow is slower, material is deposited, as
there is more friction.
- Oxbow Lakes
- Over time the meander become tighter, until the ends
become very close together. As the river breaks through,
the ends join,. The loop is cut-off from the main channel,
forming an oxbow lake.
- Over time the meander become tighter, until the ends
become very close together. As the river breaks through,
the ends join,. The loop is cut-off from the main channel,
forming an oxbow lake.
- The force of the water erodes and undercuts
the river bank on the outside of the bend where
water flow has most energy due to decreased
friction. On the inside of the bend, where the
river flow is slower, material is deposited, as
there is more friction.
- In the middle course the river has more energy and a high
volume of water. The gradient here is gentle and lateral
(sideways) erosion has widened the river channel. The river
channel has also deepened.
- Shallower valleys
- Smaller load- large rocks
- Meanders
- Lower course
- Floodplain
- The river now has a wide floodplain. A floodplain is the
area around a river that is covered in times of flood. A
floodplain is a very fertile area due to the large amounts of
sediment (alluvium) deposited by flood-waters. This makes
floodplains a good place for agriculture.
- The river now has a wide floodplain. A floodplain is the
area around a river that is covered in times of flood. A
floodplain is a very fertile area due to the large amounts of
sediment (alluvium) deposited by flood-waters. This makes
floodplains a good place for agriculture.
- Deltas
- Deltas are found at the mouth of large rivers. A delta is formed when the river deposits its material
faster than the sea can remove it.
- Arcuate or fan-shaped
- The land around the river mouth arches out into
the sea and the river splits many times on the
way to the sea, creating a fan effect.
- The land around the river mouth arches out into
the sea and the river splits many times on the
way to the sea, creating a fan effect.
- Cuspate
- The land around the
mouth of the river juts out
arrow-like into the sea.
- The land around the
mouth of the river juts out
arrow-like into the sea.
- Bird's foot
- the river splits on the way to the sea, each
part of the river juts out into the sea, rather
like a bird's foot.
- the river splits on the way to the sea, each
part of the river juts out into the sea, rather
like a bird's foot.
- Deltas are found at the mouth of large rivers. A delta is formed when the river deposits its material
faster than the sea can remove it.
- Small load- smooth pebbles and sand
- Floodplain
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