Water On The Land Flashcards
What is the hydrologicak cycle?
The constant movement of water between land, sea and the atmosphere
What type of cycle is the hydrological cycle?
A continuous cycle, no beginning or end
What is river erosion?
The wearing away of the Earth’s surface by rivers
Where does river erosion occur?
The upper course because the land is steeper
What are the two erosional directions?
Lateral and vertical
What is hydraulic action?
The sheer force of the water against the bed and banks of the river
What is abrasion?
When the load that the river is carrying repeatedly hits the bed and banks of the river causing sime of the material to break off
What is attrition?
When stones and boulders that are carried in the river hit and knoch into eachother are weakened over time. Bits fall off and they reduce in size
What is solution?
The chemical action of rivers. Only occurs when the water flows over certain rocks like limestone because its soluble and dissolves in water
What are the four methods of transportation?
Traction, saltation, suspension, solution
What is traction?
Large boulders rolling along the river bed - this is the method with the most amount of energy required
What is saltation?
Smaller pepples that are bounced along the river bed, picked up then dropped as the flow in the river changes
What is suspension?
The finer salt and silt sized particles are carried in the flow of the river giving the river a brown appearance
What is solution? Transportation
Minerals dissolved in the water of the river which can’t be seen
Why is the rivers load often deposited?
Because the amount of energy in the river drops
Where does verticle erosion occur?
Upper course of the river
Where does lateral erosion occur?
Lower and middle course of the river
How is a waterfall formed?
Water falls over a ledge.
Water in the plunge pool flicks rocks up into soft rock (hydraulic action) to erode it
Forms and undercut and the hard rock becomes an over hang
Over time it becomes so weak it breaks off
Eventually the waterfall retreats
Why is a meander formed?
Lateral erosion
The river uses surplus energy by swinging one way and the other
Where are meanders usually found?
Middle and lower course of a river
Where is there more energy in a meander? And what does it cause?
Outside bend, erosion
Where does deposition occur in a meander?
On the inside of the bend
How is an oxbow lake formed?
The neck of the meander narrows and eventually joins together to cut off the bend because the river finds the shortest course where there can be a strong current
What is a levée?
A natural embankment
