Describe and Explain the Formation of Channel Features That Can Be Created by the Process of River Rejuvenation

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Describe and explain the formation of channel features that can be created by the process of river rejuvenation (15 marks) The long profile of a river is not a static entity and is prone to change due to changes in sea level. Over very long periods of time large changes in sea level can drastically alter the rivers potential energy and can increase the chances of vertical erosion. Sea levels change because of two principal causes - isostatic changes and eustatic changes, both of these changes can lead to rises or falls in sea level. Isostatic changes are local changes where the height of the land changes relative to the global sea level. An example of this can be found in glaciation. During glaciations the weight of ice pushing on the Earth can depress the crust, causing the land to fall relative to the level of the sea. When the ice goes in warmer periods the land rebounds upwards as Scotland and Northern Britain are today - rising relative to the level of the sea. Eustatic sea level change is a GLOBAL change in sea level, linked directly to the temperature of the Earth. In warmer periods there is less ice and the water is warmer, so expands and sea levels rise. In colder periods the ocean water is colder so contracts and sea levels fall. There are also other land changes that occur, such as knick points, river terraces and incised meanders. Knick points are the part of the river/channel where there is a sharp change in channel slope, such as a waterfall. Knick points reflect different conditions and processes on the river often caused by previous erosion. River terraces are where vertical erosion occurs in a floodplain that was previously being formed by the normal conditions of deposition and lateral erosion. The river cuts downwards and abandons the old flood plain as a river terrace. Over time once the profile is regraded, the river may
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