1.6 River Landforms Flashcards
Where are potholes commonly found?
They are commonly found close to the source of the river over bedrock, such as rapids and waterfalls
What are potholes?
Potholes are small circular depressions in the riverbed, carved out of solid rock.
How are potholes formed?
When rock fragments ‘drill’ holes in the turbulent water, they can enlarge over time
What are rapids?
Irregularities of rock creating turbulent stretches of a river
How are rapids formed?
When tough resistant rock do not erode as easily as weaker rocks forming irregular steps in the long profile of a river
What are the characteristics of rapids?
White water, jagged rocks, plunges, mini-waterfalls, whirlpools and fast-flowing water
Where does a waterfall retreat towards?
The source
What is a meander?
A sweeping bend made by a river
Where are meanders found?
In lowland areas, middle course
What is the thalweg?
The line of greatest velocity or fastest flow within the river
What are riffles?
Shallow, fast flowing
What are pools?
Deep, slow flowing
What is an oxbow lake?
When two meanders migrate until it is completely cut off due to high flow conditions
What is braiding?
When a river is sub-divided into many separate channels
Why does braiding occur? When does it occur?
When a river is overloaded with sediment and it drops the load to form islands. These channels steepens the gradient and increases their efficiency
