River types and actions

V- shaped valleys and interlocking spurs

• Vertical erosion occurs in the upper course of the river.
• The river is steep and gravity pulls it down hill so it erodes deeply into the soil.
• The rocks of the valley slide down to make a V shape.
• Interlocking spurs are like a zip.
• The river does not have enough energy to erode the harder spurs of rock so it flows around them, leaving harder rock spurs sticking out while softer rock erodes in.
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Meanders

• You get curves and bends as the river flows around harder rock.
• Water is fastest on the outside edge of the bed so erodes more.
• Its is slower on the inside so deposits here,
• Over time these bends get larger and larger, until they might be cut through during a storm.
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Oxbow lakes

• Cut off meanders.
• When a meander gets too large its 'neck' becomes tight and the water really slows down so too much deposition occurs.
• Then, when a storm happens a new fast straight channel is eroded straight past, cutting off the old bend which gets left behind as a lake.
• Over time this lake dries up.
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Floodplains

• The area of land either side of the river in the lower course that gets flooded.
• Very fertile flat land is available here because of rich soils that get deposited after floods.
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Mouth

• The end of a river where it flows into a lake or the sea.
• The mouth might form an estuary or a delta.
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Delta

• A deposition landform.
• Usually triangular shaped.
• When the river reaches the sea the water slows down rapidly and deposits its material.
• The load builds up and the river gets broken up into lots o smaller tributaries.
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Estuary

• The deep and wider end of a river when it enters the sea.
• Water from the sea may low up into the river at high tide.
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