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Geography AS > DESERTS > Flashcards

DESERTS Flashcards

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1
Q

What is a desert?

A

High rate of evapotranspiration which exceeds precipitation

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2
Q

Hyper-arid is..

A

<50mm a year

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3
Q

hammada

A

Barren and rocky ground

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4
Q

reg

A

gravel/pebble plain between Hammada and erg

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5
Q

erg

A

Mostly sand dunes

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6
Q

What factors affect soil development

A

Climate, topography, time, vegetation and parent material

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7
Q

Desert soils are called…

A

aridisols

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8
Q

aridisols are..

A

Infertile and thin because of a lack of rotting material and vegetation nut mineral rich because they do not get washed out by the rain

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9
Q

xerophytes

A

Plants which adapt to desert conditions

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10
Q

Properties of xerophytes

A

Separately distributed- no sharing
Long roots up to 15m to reach sources below the ground
Small way or thorny leaves to protect from predators and reduce transpiration

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11
Q

What are succulents

A

Can expand to store water after an event of rainfall - cacti

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12
Q

4 atmospheric processes

A

Continentality
Rainshadow effect
Cold ocean currents
High pressure

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13
Q

High pressure

A

Hot wet air rises from the equator through convection
As the air heads to the poles it rains and becomes dry and dense creating high pressure on the ground (Anticyclone)
A lack of clouds also increases evapotranspiration

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14
Q

Continentality

A

Lack of impact from oceans

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15
Q

Rainshadow effect

A

Where rain is dumped on the windward side of the mountain cause it condenses on the mountain
Then pressure on the leeward side sinks and warms up the dry air creating a desert

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16
Q

Cold ocean currents

A

Cold seas create cold air which is denser than warm air and sinks to the ground
This results in high atmospheric pressure where the cold air from the ocean meets the warm dry air
This creates cold fog which sinks instead of rising and raining

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17
Q

Weathering process’s

A

Chemical or biological weathering – not common in the desert due to an absence or vegetation and rotting materials

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18
Q

Mechanical weathering - insulation weathering

A

Expansion and contraction of rocks surface layer due to extreme temp fluctuations

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19
Q

Wind transportation in deserts

A

Traction = Surface Creep
Saltation - rocks are hit forward by smaller particles
Suspension

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20
Q

Exogenous river

A

The source in outside the desert region

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21
Q

Endoreic rivers

A

Terminate in deserts into a lake or a sea

22
Q

Ephermal rivers

A

Flow seasonally or temporarily

23
Q

Landlords associated with wind

A

Yardage
zeugen
barchans
seifs

24
Q

Landlords associated with water

A 
wadis
Canyon
Mesa
Buttes
Alluvial fan
Inselbergs
badlands
25
Q

Yardang

A

Parallel elongated ridges parallel to the prevailing wind formed by wind abrasion

26
Q

barchan

A

Crescent shaped sanding - horns are in the direction of the dominant wind direction

27
Q

seifs

A

Longitudinal elongated sand dunes which form parallel to prevailing wind

28
Q

wadis

A

Steep dried out river valleys, a large Wadis is a canyon, and alluvial fan can often be found at the bottom

29
Q

Mesa

A

Large risen plateau formed by river erosion

30
Q

Buttes

A

Same as mesa but smaller pinnacles of rock

31
Q

inselberg

A

more rounded relic landforms that form in rocks like granite where there is an absence of layering, therefore the surface is much smoother

32
Q

Badlands

A

– a semi-arid landscape intensely carved by heavy rainstorms and impermeable rocks

33
Q

How much of the world is affected by desertification according to the UN

A

A third

34
Q

Human cause of desertification

A

Over- cultivation – intense farming can reduce soil fertility and its capacity to retain moisture
Over-grazing – Grassland has a sustainable carrying capacity for animals and vegetation and soils deteriorate
Over-irrigation - an excess of water can create salinization and form an impermeable and infertile salty crust
Tourism- road building, deforestation etc.
Over population
Deforestation

35
Q

Location and things happening in the sahel

A

Edge of Sahara
Belt of 1000km
Poorest countries on earth
Border conflicts, kidnapping, movement of arms and drugs, oil gas and gold reserves
Since 1960 the Sahara expands south 2-5 km a year

36
Q

Since what year has the share expanded how much south

A

Since 1960 the Sahara expands south 2-5 km a year

37
Q

Cause of desertification in the sahel

A

Population increase
Firewood
overgrazing
drought

38
Q

How many people like in the sahel and doubling time

A

260 million

20 year doubling time

39
Q

Population increase in the sahel % and % of increase in food production

A

3% a year and food production is at 2%, therefore there is additional pressure for over-farming

40
Q

How is the sahel being managed

A

Fences and trees to reduce effects of wind erosion
Promoting solar ovens to reduce the demand for firewood
Green-wall project in Senegal with a 15km tree belt
The Eden reforestation project charity- over 1 million trees are being planted in Ethiopia and Sudan

41
Q

States of the Mojave

A

Cali, Nevada, Utah, Arizona - home to death valley, hottest place in the world atm

42
Q

Issues in the mojave

A 
Urban expansion
Water supply
Military training
Conservation
Waste management
Tourism
43
Q

Mojave- Urban expansion

A

Population expected to triple in next 20 year- retirement and big cities like las vegas
Shortages in water and land - conflict

44
Q

Mojave- water supply

A

California Aqueduct transport water from the Nevada mountains to stop strain on the Colorado river

45
Q

Mojave- military training

A

DoD work with the BLM to conserve biological resources

46
Q

Mojave- conservation

A
  • $93 million was spent within 10 years to successfully bring the Mojave desert tortoise from he brink of extinction
47
Q

Mojave- Waste management

A

2009 a landfill site near the Joshua Tree NP was halted

48
Q

Mojave- tourism

A

Designated off road areas prevent off-road vehicles from damaging vulnerable areas

49
Q

Difference between the sahel and Mojave - region

A

sahel is an international region where it is hard to come to agreements

50
Q

Difference between the sahel and Mojave - economy

A

sahels surrounding countries are amongst the poorest in the world therefore more money is spent on development not desert management whereas the USA is the largest economy in the world

51
Q

Difference between the sahel and Mojave - political

A

Political instability means there few links between countries and money is often spent on weapons and defence whereas The USA has well-respected environmental groups with a strong government

52
Q

Difference between the sahel and Mojave - population per rainfall

A

Rainfall seems to be becoming more and more un reliable with a rising population whereas in the US there is a stable population so desertification kept under control

Geography AS (6 decks)

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