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🌍Geography > 🟢11 Isostacy > Flashcards

🟢11 Isostacy Flashcards

1
Q

Define Isostacy

A

The adjustment the earths crust undergoes as it sinks/rises up from the mantlw

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2
Q

Define Isostatic Readjustment

A

The sinking downwards of land due to the weight of ice

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3
Q

Define Isostatic Rebound

A

When land moves upwards following melting of ice sheets

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4
Q

Name 4 things that occur as impact of isostacy on fluvial processes

A

Rejuvenation
Knick Points
Incised Meanders
Paired Terraces

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5
Q

What is rejuvenation

A

When a river becomes youthful again

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6
Q

Explain river rejuvenation and why it happens

A

When theres a change in sea level compared to land level (caused by either falling sea level or rising land level)

River must adjust to new base level

Erosion of river channel starts in lower stage and works backwards up along the channel until the profile is completed.

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7
Q

Give example of where knick points can b found

A

River Barrow Co.Killenny

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8
Q

Give an example of where incised meanders can b found

A

River Barrow Co.Carlow

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9
Q

Give an example of where paired terraces can b found

A

River Barrow Co.Kilkenny

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10
Q

What are knick points

A

Changes in slope along a river profile
Marks the point of change in the rivers profile
Very marked knick point can form a waterfall

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11
Q

What are Incised meanders

A

Meander thats been eroded deep into the landscape
Rejuvenation causes vertical erosion on meanders which then causes them to be incised into the landscape
-Entrenched
-Ingrown

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12
Q

What are the 2 types of incised meanders

A

-Entrenched
-Ingrown

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13
Q

What are entrenched meanders

A

Steep slopes on both sides

Vertical erosion is so rapid that theres not enough time for lateral erosion to take place

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14
Q

What are ingrown meanders

A

Outer bend has steep slope, Inner bend has gentle slope

Slower rate of vertical erosion allows lateral erosion to occur

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15
Q

What are paired terraces

A

In mature stage, rivers develop floodplains
With rejuvenation, vertical erosion incises it into the flood plain
Lateral erosion creates a new floodplain

_ /
\______/ <- PT VS normal->. \______/

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16
Q

Define paired terraces

A

Terraces occurring at different levels above the current floodplain.

17
Q

Define Eustatic Movement

A

Change in sea level - it falls when water is ‘locked up’ as ice and rises when the ice melts.

18
Q

Name the impacts isostacy has on Coastal Landforms (3)

A

Raised Beaches
Raised Cliffs
Raised Sea Caves

19
Q

Give an example of a raised beach

A

Ballyhillin, Malin Head, Co.Donegal

20
Q

What is a raised beach

A

A beach which is today above the level of high tides

With Isostatic adjustment, the uplift of the land resulted in beaches being raised above sea levels.

No longer affected by marine processes, still subject to weathering

21
Q

What is a peneplain

A

low lying flat area of land

22
Q

What is peneplain formed as a result of

A

Formed as a result of extensive fluvial processes

23
Q

What was William Morris Davis theory on landscape development?

A

Rivers etc. will eventually reduce an uplifted landmass to a low featureless peneplain

24
Q

Name the three stages to William Morris Davis cycle of erosion theory

A

Youth
Maturity
Old age

25
Q

Define River Capture

A

Headward erosion that extends a river upstream from its source diverts (captures) water from other rivers and streams into its own channel.

26
Q

What happens in stage ONE of WMD’s geographical cycle of erosion theory

A

Uplift has stopped
Erosion begins
Streams flowing over the surface erode their valley floors forming deep V-shaped valleys
Headward erosion extends river channels leading to river capture
Rapids,waterfalls,gorges formed here

27
Q

What happens in stage TWO of WMD’s geographical cycle of erosion theory

A

Landmass is now well drained by rivers that have dissected it forming ridges and valleys
Vertical erosion overtaken by lateral erosion
Meanders and floodplains appear

28
Q

What happens in stage THREE of WMD’s geographical cycle of erosion theory

A

Rivers have reached their base level
lost their erosive ability
deposition is main activity
Landscapes been reduced to a peneplain

29
Q

Example of a peneplain Ireland

A

Co.Cork to Co.Waterford
South Ireland Peneplain
Elevations ranging between 200m and 250m

30
Q

What is eustacy

A

Relates to global changes in sea level caused by formation and melting of vast continental ice sheets.
Occurs when temps drops during ice age

🌍Geography (13 decks)

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