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ESSOCP: Geosphere > Landscape Evolution > Flashcards

Landscape Evolution Flashcards

1
Q

What is spatial evolution?

A

How a process or landform changes in its dimensions and shape

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2
Q

What are the three dimensions/axis used to measure spatial evolution?

A

X (Latitude), Y(Longitude), Z(Height)

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3
Q

What is the importance of the Z axis in spatial evolution?

A

It sets the amount of energy that goes in to a system. This is because height determines potential energy which affects relief, runoff rates etc.

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4
Q

What is temporal evolution?

A

Evolution over time usually using models for landforms that are difficult to monitor

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5
Q

What are many of the earth’s landscape shaped by?

A

Fluvial processes such as rainfall and erosion

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6
Q

What are the three types of model used to understand fluvial systems?

A

Numerical, experimental and conceptual

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7
Q

What type of model was WM Davis’ ‘cycle of erosion?

A

Conceptual

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8
Q

Who’s work did WM Davis’ ‘cycle of erosion’ closely follow?

A

Darwin’s evolutionary model

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9
Q

What did WM Davis’ ‘cycle of erosion’ model?

A

The changes in a fluvial landscape over time.

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10
Q

Outline the stages within WM Davis’ ‘cycle of erosion’ and the processes determining them

A

It begins solely with UPLIFT creating a starting platform, then this would be met with down cutting in YOUTH, over time these would both diminish and the landscape would MATURITY with the emergence of hills, finally it would transition in to OLD AGE where it would become very flat

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11
Q

What are the three key concepts within the ‘cycle of erosion’ model?

A

Potential Energy: Potential for erosion determined by land surface height above…
Reference/Base Level: This can be sea level or localised and is what erosion works toward to
Peneplanation: Reduction in the relief, altitudes and highest divides over time

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12
Q

What are three areas of simplification within the ‘cycle of erosion’ model?

A

Renewed Uplift: The model ignores the possibility for renewed uplift
Climate: It can vary between two extremes which can drastically alter things
Geology: Too complicated at the time but this can drastically alter process rates

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13
Q

What was Penck’s alternative to Davis’ model?

A

He devised a model that did account for renewed uplift unlike Davis

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14
Q

What was King’s alterative to Davis’ model?

A

He devised a model from South African fluvial systems consisting of irregular patterns. the model therefore acknowledged the variation in geology over a system

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15
Q

What followed on from the three conceptual models developed by Davis, Penck and King during the 19th Century?

A

More numerical and experimental models, deriving from the abilities of geography after the quantitative revolution

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16
Q

What are the most important landscape evolution mechanisms?

A

Uplift, Isostatic Response to erosion, denudation

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17
Q

What is orogenic uplift?

A

Horizontal compression generated by folding of the earth’s crust causes the landscape to rise

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18
Q

What is an example of orogenic uplift and the rate of uplift?

A

Himalayas 5-10mm yr^-1

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19
Q

What is epeirogenic uplift?

A

Vertical forcing generated by the elevation of wide areas of the earth’s crust due to large changes in the lithosphere

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20
Q

What is an example of epeirogenic uplift and the rate of uplift?

A

Colorado Plateau 0.1mmyr^-1 or a lot of Africa

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21
Q

What is the main difference between Orogenic and Epeirogenic uplift?

A

Orogenic is much faster and localised compared to Epeirogenic that is very slow but broad in geographical coverage

22
Q

How do you need to think of mountains to understand their isostatic response to erosion and why?

A

Icebergs. This is because they are essentially floating as part of the lithosphere due to their lower relative density

23
Q

What is the isostatic response to erosion of mountains?

A

By eroding part of the mountains above the earth’s crust this affects their density and because they are floating, part of the mountains below the crust will float back up to fill the space created by its erosion

24
Q

How much of the eroded landscape is replenished by isostatic rebound to erosion?

A

80-85%

25
Q

What is the rate of isostatic response in places such as Canada and Scotland?

A

~100mmyr^-1 but then slows down after a few thousands of years

26
Q

What is a side effect of the exhumation generated through isostatic response to erosion?

A

If some areas rise then others surrounding them will subside

27
Q

What is an area of subsidence caused by isostatic response to erosion?

A

Devon and Cornwall are amongst areas subsiding due to the rise of scotland

28
Q

What is denudation?

A

the process wearing away and causing a reduction in the elevation of earth’s surface

29
Q

What are the different stages of denudation?

A

Weathering, Transportation and Deposition

30
Q

What is physical weathering?

A

Fracturing of rock through freeze-thaw variations as well as collisions of rock and sand

31
Q

What is chemical weathering?

A

Dissolution of the rock. The rates are dependant upon the rock and solution type but eventually all disolve

32
Q

What is biological weathering?

A

Roots contain acids that can dissolve rocks and minerals in the ground to access nutrients such as phosphorus and nitrogen

33
Q

What are all weathering processes dependant upon?

A

temperature and moisture

34
Q

What are the four mechanisms of transportation?

A

Water: Rivers and Oceans etc.
Glaciers: Melting, mass movements
Mass Movement: Can remove large sums of material from a landscape
Wind: Transports fine material

35
Q

What is the term given to describe the material transported within rivers?

A

‘Load’

36
Q

what is the estimated structure of a river’s transported load?

A

Bedload: 10%
Suspension: 70%
Dissolved: 20%

37
Q

What are the four main sites of deposition?

A

Footslope
River Floodplains
Intertidal zones (Deltas or estuaries)
Open Sea

38
Q

what sort of material is deposited at footslopes?

A

Coarser material before it reaches the main channel

39
Q

What sort of material is deposited at floodplains?

A

Coarser sediments

40
Q

What sort of material is deposited at intertidal zones and what does this enable to form?

A

Fine sediments that can form landforms such as deltas and estuaries

41
Q

What sort of material is deposited in the open sea and what can form with an example?

A

suspended or dissolved load such as clay that can form continental shelves like the Bengal Fan

42
Q

How does mean relief of the fluvial system affect denudation rates?

A

It increases potential energy that can therefore increase erosion rates

43
Q

How does the time since uplift affect denudation rates?

A

With increased time since uplift the elevation of fluvial systems decreases

44
Q

How does climate affect denudation?

A

Starting with a completely dry landscape that is exposed, increased rainfall causes more erosion, however at a point the rainfall improves soil quality that leads to vegetation which acts as a natural barrier against erosion. Eventually the rainfall becomes too powerful for the vegetation to handle so denudation increases

45
Q

How doe lithology affect denudation?

A

Earthquakes can drastically increase the amount of erosion as found in Taiwan which has very responsive systems

46
Q

Which study discovered the effect of earthquakes and typhoons on Taiwan fluvial systems?

A

Dadson et al. 2013

47
Q

How does river incision rate affect denudation?

A

The speed at which river cuts down through the valley and channel affects relief which increases denudation

48
Q

How do glaciers affect denudation rates?

A

Glaciers can retreat and subsequently erode a valley by scraping material from the landscape which increases denudation. However, the melting of glaciers will cause the land to isostatically rebound.

49
Q

How can sea level affect denudation?

A

Sea level can respond to Eustatic and isostatic changes as well as tectonic controls. this can cause land to emerge and alter the base/reference level

50
Q

How can typhoons/extreme weather events affect denudation?

A

They can drastically deprive/provide fluvial systems of water which can either drastically increase or decease denudation rates

ESSOCP: Geosphere (7 decks)

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