Describe and explain the formation of landforms of river rejuvenation.

The command words are ‘describe’ and ‘explain’, so a good answer should address both. The question focuses on landforms of rejuvenation and therefore you should refer to features such as knickpoints, incised meanders (ingrown and entrenched), and river terraces (paired and unpaired).A short introduction should give some context to your answer, by defining rejuvenation and highlighting its causes.For example…‘River rejuvenation occurs when the river’s base level falls, which in turn refers to the lowest point at which a river can flow and erode. Rejuvenation is caused by isostatic change, which sees a relative change in base level (e.g. a decrease in land level, relative to the sea), or eustatic change, which sees an absolute change occur (e.g. the sea level itself falls).’The main body of your answer should form three paragraphs, each one concentrating on a different landform – knickpoints, incised meanders and river terraces. Look to define each feature, describe it and explain its formation. A good way to describe is to use LESS: location, example, size and shape of each landform. That is where along the river’s course is it located, an example from around the world, its shape and size. But don’t worry if you can’t do this all the time!For example…‘A river terrace is a narrow, flat strip of land that runs parallel to the river’s banks, above the level of the floodplain. Younger terraces more uniform, whereas older terraces are less so, due to erosion over time. There are two distinct types of terraces, namely paired and unpaired, which are found in the middle and lower course of the river. Paired terraces see down-cutting as the dominant process, as vertical erosion is faster than lateral erosion; this is because the river has more energy, which results in the sides being parallel. For example, Boyn Hill (higher and older) and Taplow terrace (lower and younger) on the Thames. Whereas, with unpaired terraces, lateral migration is the dominant process, which results in a wider cross profile and an asymmetrical channel, due to erosive meandering.’This can then be repeated for knickpoints and incised meanders.For example…‘A knickpoint is the point at which new readjusted profile meets the old river profile. Knick points are usually marked by rapids and waterfalls, which represents rejuvenation, as there is a sudden break in the long profile of the river. Knickpoints are formed when the river the river cuts down, adjusting its profile to a new base level. This causes a sudden change is gradient, after which the knickpoint moves upstream via headward erosion as river adjusts to a new energy balance. For example, Breezley Falls along the River Greta in Yorkshire, and the Horseshow Falls in Canada, which has retreated 11 km over 10,000 years – both represent knickpoints in the form of waterfalls, and are found in the lower and middle course of the river.’‘An incised meander is one that has cut deeply into the floodplain, creating a steep, cliff-like river banks – they can be either entrenched or ingrown. Entrenched meanders are formed by rapid incision, which results in a meander that has steep sides and a symmetrical valley shape, because vertical erosion is the dominant process and therefore the river does not have chance to meander laterally. This gives a gorge-like appearance, such as the one that is seen on the River Wye in Tintern, South Wales. Whereas, ingrown meanders are formed by slower incision, which gives the river chance to erode laterally and therefore form an asymmetrical valley, which has gentle slip-off slopes on the inner bends and steep, cliff-like banks on the outer bends. This is because lateral erosion is the dominant process, as seen on the Goosenecks of the San Juan River in Colorado.’A way to remember the difference in to think about a WWI trench and an ingrowing toenail. A WWI trench had steep sides and was dug deep into the ground – hence an enTRENCHed meander.Whereas, an ingrowing toenail grows into the side of the toe, like a meander – hence an INGROWN meander.A conclusion to this answer isn’t essential, but if you do choose to include one, it should sum up the main processes of river rejuvenation and how they affect the landform created.