Chapter 8 - The Work of Rivers Flashcards
Define tributaries.
Smaller rivers that join a larger river.
Define confluence.
The place where a tributary joins the main river.
Define estuary.
The tidal mouth of the river.
Define delta.
Land that forms at the mouth of rivers.
Define mouth.
Where the river enters the sea or lake.
Define distributaries.
Small rivers that break off from the main river as it enters the sea.
Define basin.
The area drained by the river and its tributaries.
Define course.
The path of the river from source to mouth.
Define source.
Where the river begins.
What is erosion?
Erosion is the wearing away of rock, the transport of that rock and its deposition. This is carried out by rivers, moving ice and the sea.
Define load.
The material transported by a river.
How do rivers erode?
(a) Hydraulic action
(b) Abrasion
(c) Attrition
(d) Solution
Define hydraulic action.
This is erosion carried out by the force of the flowing water in the river.
Define abrasion.
The river uses its load (of earth and rocks) to erode the bed and banks (channel of the river).
Define attrition.
The river’s load is worn down when the pieces collide so that the stones are smoothed and made smaller.
Define solution in erosion.
Some rocks, such as limestone, are dissolved in the river.
How do rivers transport?
(a) Solution
(b) Saltation
(c) Suspension
(d) Traction
Define solution in transportation.
Rock minerals are dissolved in the water and get carried away invisibly.
Define saltation.
Small stones are bounced along the bed of the river.
Define suspension.
Light material, such as silt, is transported in the water.
Define traction.
Larger rocks are rolled along the riverbed.
What is deposition?
(a) When a river slows down, it loses energy, so it deposits some of its material or load.
(b) This happens when a river enters a lake, when a rivers slows down on a flat plain or when a river enters the sea. It also happens on the inner bend of a meander.
Define watershed.
The line dividing the waters of a river and its tributaries (river basin) from those of another river and its tributaries (another river basin).
