Chapter 8- Rivers Flashcards

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1
Q

What is the source?

A

Where the river begins

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2
Q

What is the course?

A

The path of the river from source to mouth

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3
Q

What are tributaries?

A

Small rivers that join a larger river

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4
Q

What is the watershed?

A

A line dividing the waters of a river basin from the waters of another river basin

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5
Q

What is a delta?

A

Land that forms at the mouth of a river due to deposition

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6
Q

What is the mouth?

A

Where the river enters the sea or lake

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7
Q

What is the basin?

A

The area drained by the river from source to mouth

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8
Q

What is a confluence?

A

The pace where a tributary joins the main river

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9
Q

What is an estuary?

A

The tidal mouth of a river

Transition between river and sea, affected by the tide

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10
Q

What are distributaries?

A

Smaller rivers that break food from the main river

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11
Q

What is the material transported by a river called?

A

Load

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12
Q

What are the 4 methods of river erosion?

A

Hydraulic action
Abrasion
Attrition
Solution

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13
Q

What is hydraulic action?

A

The force of moving water eroding the bed and the banks

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14
Q

What is abrasion?

A

The load hitting of the bed and the banks wearing them away

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15
Q

What is attrition?

A

The load hitting off itself, wearing itself down

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16
Q

What is solution?

A

Rock minerals dissolve in a river and are carried away

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17
Q

What are the four methods of river transport?

A

Solution
Suspension
Saltation
Traction

18
Q

What is suspension?

A

Light material e.g. Silt is transported in the water

19
Q

What is saltation?

A

Small stones are bounced along river bed

20
Q

What is traction?

A

Large rocks ate rolled along riverbed

21
Q

What is deposition?

A

When a river slows down, it loses energy so it deposits some of its load

22
Q

What are the 3 stages of a river?

A

Youthful
Mature
Old-age

23
Q

What are th characteristics of the youthful stage?

A

Steep slope
Fast moving
V-shaped valley: steep sides, narrow floor

24
Q

What are the characteristics of the mature stage?

A

Slower moving
Wider
Gentle slope
Mature valley: gentle sides, wide floor

25
Q

What are the characteristics of the old age stage?

A

Slow
Meandering
Almost flat slope
Plain: little/no valley

26
Q

What stage is river erosion most active?

A

Youthful

27
Q

What is vertical erosion?

A

Wearing away of river bed

28
Q

Name 2 landforms of the youthful stage of a river

A

V-shaped valley

Waterfalls

29
Q

How are v-shaped valleys formed?

A

River wears down valley floor
Weathering wears back slopes of valley
Gravity causes regolith on valley sides to move downslope

30
Q

What are interlocking spurs?

A

When sides of a belly jut into each other

-created when youthful river avoids hard rocks

31
Q

When do waterfalls occur?

A

When a river falls from a height

32
Q

How are waterfalls formed?

A

A band of hard rock lies next to a band of softer rock
River erodes soft rock faster, creating waterfall
Plunge pool develops at base- caused by hydraulic action and abrasion
River undercuts harder rock creating overhang
Rock over head collapses
Waterfall retreats up stream

33
Q

Name an example of a waterfall

A

Powerscourt Waterfall, Co. Wicklow

34
Q

Name 2 landforms of the mature stage

A

Floodplain

Meander

35
Q

What is a floodplain?

A

A flat area along the river corse that is flooded by the river
As the river floods it lays down alluvium on the valley floor

36
Q

What is alluvium?

A

Mixture of clay, silt, sand, gravel and other material

37
Q

What are meanders?

A

Bends in the river in the mature and old age stages

38
Q

How are meanders formed?

A

*when river wears away on its outer bend and deposits on its inner bend
1. Water flows faster on outer bend- erodes bank by undercutting causing it to collapse
2. Water flows slower on inner bend- deposits load here
This continues and meander becomes more prominent

39
Q

Name three landforms of the old-age stage

A

Ox-bow lakes
Levees
Deltas

40
Q

What is an ox-bow lake?

A

A curved shape of water formed when a meander in a river is cut off leaving the river to straighten its course

41
Q

How are ox-bow lakes formed?

A
  1. River forms a meander
  2. River erodes land on outer bends
  3. River deposits on inner bends
  4. During a flood, river breaks through to straighten course
  5. Meander is cut off from river ti form ox-bow lake
    Eventually lake will dry out, leaving the shape in the landscape
42
Q

What is a levee?

A

A raised bank of earth running along the sides of a river