Physical (Rejuvenation) Flashcards
How are landforms created from rejuvenation
The river adjusts to is new base level, forming landforms
What landforms can be created from rejuvenation
Knickpoints, waterfalls, rapids, terraces, incised meanders
What is an incised meander
A meander which has cut deeply into the floodplain, creating steep cliff like banks.
What is a knick point
Usually marked by rapids, this represents rejuvenation and is a sudden break in the long profile of the river
What is rejuvenation
An increase in the energy of a river caused by either a fall in its base level or an uplift of the land
What is a river terrace
A narrow, flat piece of ground that runs parallel to the river on either side, above the level of the flood plain. They are usually created following a fall in base level.
How is a knick point formed
The river gains renewed cutting power as the new base level adjusts at the sea and works its way back, the long profile is adjusted. A knick point is where the long old profile joins the new and it recedes upstream.
When does rejuvenation occur
When there is either a fall in sea level relative to the level of the land or a rise of the land relative to the sea.
(This enables a river to renew its capacity to erode as its potential energy is increased)
How is a waterfall formed from a knick point
It can be formed due to the rock type or to rejuvenation. Headward erosion upstream may mean that a waterfall cuts back through the valley towards its source until the long profile eventually adjusts to its new energy equilibrium.
Why are terraces useful
They provide shelter from floods in a lower course river valley and natural route ways for roads and railways
Why are incised meanders formed
Because they have renewed energy, the nature of the landforms is largely a result of the rate at which vertical erosion has taken place
When is an an ingrown meander formed
when incision is slow and lateral erosion is occurring
What do ingrown meanders look like
- the valley is asymmetrical with steep cliffs on the outer bends and more gentle slip off slopes on the inner bends
What are entrenched meanders
With rapid incision, where down cutting or vertical erosion dominates, the valley is more symmetrical with steep sides and a gorge like appearance
