Landform process & change Flashcards
What processes cause river landforms to change overtime?
- fluvial erosion
- transportation
- deposition
Define fluvial
Referring to a river & its landforms
Define erosion
The process of wearing away the land
Define transportation
The movement of material by the flow of the water
Define deposition
The process of material carried by the river being dropped
Define bedload
Material carried by the river being bounced or rolled along the bed
Define meander
A bend in the river, formed by lateral erosion
What are the types of erosional processes that occur on the river channel?
- abrasion
- hydraulic action
- solution
What are the types of erosional processes that occur on the river bed?
- attrition
- abrasion
Define abrasion
Material carried by the river hitting the river bed & banks & wearing them away
Define hydraulic action
The force of the water pushing air into gaps in the soil & rocks, causing them to be wider
Define solution
When the water has a chemical reaction with rocks made from calcium carbonate (limestone/chalk) and dissolves them
Define attrition
Rocks carried by the river collide together & are broken down becoming into smaller & rounder rocks
What does river transportation depend on?
- speed of the flow
- weight of the load
What are the different ways that transportation occurs in the river?
- solution
- suspension
- saltation
- traction
Define suspension
Fine light material is carried in the river flow, as suspended load
Define saltation
Small pebbles/stones bounced along the bed & banks of the river
Define traction
Large boulders rolled along the bed & banks
Where does deposition occur in a river?
- river channel
- inside a meander
- mouth of the river
Why does deposition occur in the river channel?
There is reduced movement of water caused by lack of rainfall
Why does deposition occur in the meander?
The majority of the water is on the outer bend, therefore the water on the inner bend is slow & can’t transport load
Why does deposition occur in the mouth of the river?
The water opposes the direction of the sea
What river landforms are shaped by fluvial processes?
- v-shaped valleys
- waterfalls
- gorges
- floodplains
- meanders
Define v-shaped valley
A narrow valley with steep sloping sides found in the river’s upper course
Define waterfall
Water falling from a higher level to a lower level caused by glacial & differential erosion
What 2 ways can waterfalls be formed?
- glacial erosion
- differential erosion
Define glacial erosion
Erosion of the landscape caused by glaciers during the ice age
Describe the process of waterfall formation through glacial erosion
- during ice age, glaciers carved steep valleys into the landscape
- valleys left hanging above one another
- glaciers melted→water drains from small valleys into large ones
Define differential erosion
Waterfalls are formed due to a change in rock structure
Describe the process of waterfall formation through differential erosion?
- waterfalls occur where a band of HR overlies SR
- as water falls, hydraulic action continues to erode the SR underneath the HR
- as SR is eroded, overhang becomes heavy & collapses due to gravity, causing waterfall to retreat
- plunge pool forms underneath waterfall due to force of water hitting the river bed
Define gorge
A steep-sided narrow valley formed by a retreating waterfall
Define floodplain
A flat piece of land on either side of a river forming the valley floor
Define vertical erosion
Sideways erosion of the river channel that deepens it
Define interlocking spurs
Hard resistant rocks that a river cannot easily erode & therefore has to move around it
Define plunge pool
A deepened part of the river bed at the base of the waterfall caused by the impact of the falling water
