erosion, transportation, deposition and waterfalls Flashcards

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1
Q

name the four processes of erosion?

A
  • hydraulic action
  • corrasion
  • attrition
  • corrosion
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2
Q

how does hydraulic action occur?

A

the force of the water breaks rock particles away from the river channel

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3
Q

how does corrasion occur?

A

rocks that are being carried by the river rub against the channel, constantly wearing it away

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4
Q

how does attrition occur?

A

eroded rocks hit against one another and break into smaller fragments

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5
Q

how does corrosion occur?

A

when the river water dissolves some of the rocks, such as chalk and limestone

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6
Q

name the four types of transportation?

A
  • traction
  • suspension
  • saltation
  • solution
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7
Q

describe what happens in traction?

A

large particles of rock, such as boulders, are pushed along the river bed by the force of the water.

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8
Q

describe what happens in suspension?

A

small particles such as slit and clay are carried along by the water

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9
Q

describe what happens in saltation?

A

pebble sized particles are bounced along the river bed by the force of the water

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10
Q

describe what happens in solution?

A

soluble materials are dissolved in the water and are carried along by the river

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11
Q

what is deposition?

A

deposition is when a river drops the eroded material that it has been carrying

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12
Q

under what condition does deposition occur?

A

when a river loses velocity (slows down)

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13
Q

what causes a river to slow down?

A
  • the volume of water in a river falls
  • the amount of eroded material in a river increases
  • the water is shallower
  • the river reaches its mouth
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14
Q

which course of the river are waterfalls and gorges formed in?

A

the upper course

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15
Q

how are waterfalls formed

A

the river flows over an area of hard rock followed by an area of softer rock.
the softer rock is eroded faster than the harder rock which creates a step in the river, a steep drop is eventually created, which is called a waterfall

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16
Q

What happens to a waterfall over time?

A

the hard rock becomes undercut, becomes unsupported and collapses, the collapsed rock erodes the bottom of the river creating a plunge pool, over time more undercutting occurs and the waterfall continues to retreat.

17
Q

when the waterfall retreats what is left behind?

A

a steep sided gorge