Chapter 8.-river Action: The Work Of Rivers Flashcards
What is the source
It is where the river begins
What is the watershed
It is the lines dividing the waters of a river and its tributaries (River basin) from those of another river and its tributaries (another basin).
What are tributaries
They are smaller rivers that join a larger river.
What is a confluence
It is the place where a river tributary joins the main river
What is an estuary
Its the tidal moth of a river
What is a delta
The land that forms at the mouth of rivers
What is the mouth
Where the river enters the sea or lake
What is the course or a river
Its the path of the river from source to mouth
What is the basin
Its the area drained by the river and its tributaries
What are distributaries
They are small rivers that break off from the main river as it enters the sea
Hat are the processes of river transportation
They are saltation, traction, suspension and solution.
What is saltation
It is when small stones are bounced along the bed of a river.
What is solution
Its when rock minerals are dissolved in the water and carried away.
What is suspension
It is when light material such as silt is transported in the water.
What is traction
Its when larger rocks are rolled along the river bed
What is the old age stage
It is the last of the three stages of a river. In the old age stage the river slows down and meanders. It deposits its load either because the river is losing energy or because the load is too great.
What are three landforms of the old age stage.
Three landforms of the old age stage are levees, deltas and ox-bow lakes
What are 10 river features
10 river features are the source, watershed, tributaries, estuary, confluence, delta, mouth, distributaries, basin and the course.
What is an ox-bow lake
Its a curved shape of water formed when a meander in a river is cut off, leaving the river to straighten its course.
E.g - the river Moy, co. Mayo
How is an ox-bow lake formed
Its formed:
1.the river forms a meander
- the river wears away (erodes) the land here on the outer bends
- the river deposits on the inner bends
- during a flood, the river breaks through to straighten its course
- the meander is cut off by the river to form an ox-bow lake. Eventually the lake will dry out, leaving the shape of the old lake in the landscape.
What is a levee
Its a raised bank of earth running along the sides of a river.
How is a levee formed
Its formed when -
1.the river floods and covers the floodplain
- the river deposits silt (sediment) on the floodplain as it slows down
- the faster flowing water of the river channel comes in contact with the slower flowing water of the floodplain along the bank of the river, resulting in silt being deposited.
- more silt is deposited along the bank than on the floodplain. This forms a raised bank called a levee.
What is a delta
Its low lying sand that forms at the mouth of the river when they enter a lake or the sea.
How is a delta formed
Its formed when -
1. The river slows down and enters the lake or sea and it deposits its load to build the delta.
- The delta forms when the sea currents are not strong enough to remove the silt.
- The river breaks up into distributaries (streams that branch iff from the main channel of the river).
E.g. The Nile , Egypt
