EROSION and DEPOSITION Flashcards
What are the agents of erosion and deposition?
1) Water (rivers)
2) Sea
3) Moving ice
4) Wind
Explain how RIVERS (WATER) causes erosion and deposition
The river follows a path as it flows. This is called the course.
#The river has a STARTING point (source) and a END point (mouth)
# DEPOSITION occurs in the LOWER course where the heavier materials
are deposited (like rocks)
Name the 3 courses a river has
1) Upper
2) Middle
3) Lower
Explain the UPPER course of a river
- Beginning of the river
- Water flows QUICKLY (lots of energy)
- STEEP slope and NO deposition occur here
- EROSION occurs here that DEEPENS the valley, forming spurs
In which part of the river course does NO deposition occur?
Upper course
Why does a lot of EROSION take place in the UPPER COURSE?
REASON = River flows QUICKLY (lots of energy)
Explain the MIDDLE course of a river course
- WIDE floor
- most EROSION takes place in the width of the river
- water starts to SLOW DOWN
- more water here than in the upper course
In which part of the river course does the water flow the SLOWEST?
Lower
In which part of the river course is there NO erosion?
lower
In which part of the river course is there LOTS of deposition?
lower
Explain the Lower course in the river course
- End of water
- River flows very SLOWLY
- Lots of water
- Deposition dominates
- New landforms are formed
Why are there new landforms formed in the lower course of the river?
It has the MOST deposition
How is a U-Shape VALLEY formed?
U U U U U U U U U U U U U U U U U
> Soil / rocks are eroded by fast running water
Vertical erosion always takes place in the UPPER course of the river (as
the water flows the FASTEST)
this forms a deep valley
In which part of the river course does VERTICAL erosion take place and why?
LOCATION = upper course
REASON = fastest water flow
What is a RAPID?
River becomes shallower
# Rock is exposed above the flow surface
Give one word for when there is a huge bend in a river
Meander
How does a meander develop?
- water flow over flat land
- water flows slow on inner bend and EROSION occurs
- water flows slow on inner bend and DEPOSITION occurs
- the deposited material forms part of the FLOODPLAIN
- the OUTER bend of meander continues to erode
- the neck becomes narrower
- later the two OUTER bends meet
How does beaches form?
> When DEPOSITION occurs
Weather material are carried by rivers and DEPOSITED into the sea
EROSION occur in the sea
The waves transports material and DEPOSITED in quieter areas
Material is DEPOSITED on the shore when WAVES break
When lots of weather material are accumulated in a place
= this is how a BEACH IS FORMED
(other landforms like spits and barrier islands are also formed due to DEPOSITION)
How are U-SHAPED valleys formed through MOVING ICE?
- powerful EROSION action of glaciers
- U = characteristic U-shape with steep straight sides and flat bottom
What are moving ice called?
Glaciers
EROSION by moving ice (glaciers) are caused by 2 processes, name them
1) Abrasion
2) Plucking
Explain how erosion takes place in the ABRASION process
ROCKS in the ice scrape against ROCK on the bedrock
Explain how erosion takes places through the PLUCKING process
Pieces of bed rock under the moving ice are PULLED from the surface as the glacier moves
What are GLACIAL STRIATIONS?
Scratch / striation marks seen on rocks.
This is where glaciers have scratched lines in the rock.
