Geography- River and Coasts: Courses of the River

Upper Course
1. Interlocking spurs
  1. 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.
  2. Rapids
    1. When a river runs over alternating layers of hard and soft rock, rapids and waterfalls may form.
2. Waterfalls
  1. 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.
    1. Over time, more undercutting causes more collapses. The waterfall will retreat, leaving a steep-sided gorge.
3. Steep gradient
4. Large load- boulders.
Middle Course
1. Meanders
  1. 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.
  2. Oxbow Lakes
    1. 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.
2. 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.
3. Shallower valleys
4. Smaller load- large rocks
Lower course
1. Floodplain
  1. 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.
2. Deltas
  1. 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.
  2. Arcuate or fan-shaped
    1. 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.
  3. Cuspate
    1. The land around the mouth of the river juts out arrow-like into the sea.
  4. Bird's foot
    1. 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.
3. Small load- smooth pebbles and sand

Nächster

Geography- River and Coasts: Courses of the River

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Zusammenfassung der Ressource

Medienanhänge

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