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23 Cards in this Set

  • Front
  • Back
What are the four types of erosion?
-Hydraulic action (the force of the water breaks up rocks)
-Abrasion
-Attrition
-Solution (river dissolves some rock particles)
What are the four types of transportation?
-Traction
-Saltation
-Suspension
-Solution
What are some reasons that a river may slow down and deposit material?
-The volume of water decreases
-The river reaches its mouth
-The water is shallower
What does vertical erosion do and in which course of the river is it most dominant?
It deepens the the river valley (and channel) making it v-shaped, most dominant in the UPPER course.
What does lateral erosion do and in which courses of the river is it most dominant?
It widens the river valley (and channel), most dominant in MIDDLE AND LOWER courses.
In which courses of a river would you find a meander?
MIDDLE AND LOWER courses
How is a meander formed?
Current is faster on outside of the bend, so more erosion there, forming RIVER CLIFFS
Current is slower on the inside, so more deposition there, forming SLIP-OFF SLOPES
How is an ox-bow lake formed?
-formed from meanders
erosion causes the outside bends to get closer until it gets to a point were there's only a bit of land land between the bends (the neck), which the water eventually breaks through. Deposition cuts off the meander to form an ox bow lake
In which course of a river would you find waterfalls and gorges?
the UPPER course
By which process are waterfalls and gorges formed?
Erosion
How is a waterfall formed?
when a river flows over hard rock, then soft rock, the soft rock is eroded more, making a 'step' in the river, and as erosion continues on the area of soft rock, it eventually creates a STEEP DROP, ie. a waterfall
How is a gorge formed?
continues on from a waterfall, the hard rock is eventually undercut by erosion and collapses. a plunge pool is formed (in the soft rock) by abrasion as the collapsed rock swirls around, then more undercutting, so more collapses, and the waterfall retreats, leaving a steep sided gorge
By which process are flood plains and levees formed?

Which course of the river are they both found in?
Deposition

the LOWER course
How is a flood plain built up? (it already exists on either side of a river)
-when a river floods onto the plain, the water slows and it DEPOSITS the material its been transporting, making it HIGHER
-meanders migrate across the plain to make it WIDER
-the deposition on slip-off slopes of meanders, make it HIGHER
How are levees formed?
During a flood, eroded material is deposited over the whole flood plain, heaviest material is deposited closest to the river channel. After repeated flooding, THE DEPOSITED MATERIAL BUILDS UP, creating levees.
Define river discharge.
The VOLUME of WATER flowing in a river per second
What are the physical factors that can cause a river to flood?
-Prolonged rainfall
-Snowmelt
-Heavy rainfall
-Relief (how the height of the land changes)
What are the human factors that can cause a river to flood?
-Deforestation
-Urbanisation (building construction) -> impermeable surfaces that are built - buildings and roads - increase surface runoff and drains quickly take runoff to rivers. This increases discharge quickly, which can cause a flood
Define watershed
An area of land that contains a common set of streams and rivers that all drain into a single larger body of water (a drainage basin)
Define confluence
The meeting of two or more bodies of water
Define tributary
A river or stream that flows to a larger body of water, eg another river
Define source
Where a river starts
Define mouth
The end of the river when it joins a larger body of water, eg. the sea