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Where are cold environments found and what are the common characteristics
High latitudes and altitudes
Polar environments at north and south poles
Periglacial area before polar environment
Also cold environments in high altitude, mountainous areas.
Where are desert and semi-arid environments found and what are the common characteristics
Around the tropics
Stable low pressure conditions and large distance from the sea needed for these areas to form
Also proximity to cold, upwelling currents to limit moisture in the air
What is continentality
The distance of land from the sea. Deserts require a high continentality
Why is it difficult to develop and settle in cold and high altitude environments
Mountains are steep, so difficult to build on
This also limits transport
They also usually have thin, infertile soils which experience high levels or erosion
Periglacial areas usually have waterlogged soils and low levels of evaporation
Also a short growing season due to temperatures being high enough for only a small proportion of the year
Why is it difficult to develop and settle in desert and semi-arid environments
Lack of water
Therefore, as well as high temperatures, agriculture is made difficult
Deserts are at risk of flash floods.
What is the comfort zone
The temperature and humidity range for human habitation. Although may be culturally bias as some indigenous populations are better able to deal with the cold than some other populations
How do indigenous people cope with cold environments
Migratory patterns(moving north during the summer and south in the winter to avoid extreme cold)
The use of fishing in lakes and the sea for food as agriculture and livestock is difficult
How do indigenous people cope with desert and semi-arid
In the middle of the day they take a rest and avoid direct sunlight
They travel in early morning and late night
They wear lose fitting, thin garments to reduce sweating and overheating.
How can farmers cope with water shortages in dry areas
Reducing the size of herds
Exchange of livestock and products to suit drier conditions
Greater use of drought-tolerant species
Use of wild species and crops
Windbreaks to reduce wind erosion of bare soil
Herd diversification
What affects a glacial system
Inputs - Accumulation of snow, avalanches, debris and meltwater
Outputs- Ablation, sublimation of ice to vapour and sublimation of ice
How can we tell if a glacier is advancing or retreating
If accumulation is greater than ablation, glacier advances
If ablation is greater than accumulation, glacier retreats
If they are equal, the glacier is steady
What is some evidence for climate change in the Sahara Desert
Pollen from oaks and cedars, and small crocodiles found in the mountains
Ancient civilisations leaving cave paintings
Wadis left over from dried up rivers
What is plucking
A method of glacial erosion
Occurs at the base or the glacier, and sometimes at the sides
It is most effective in weakened rocks by joints/weathering
As ice moves, meltwater seeps into the joints, freezes onto the rock, and then is ripped out by the moving glacier
What is abrasion
A method of glacial erosion
Debris carried by the glacier scrapes and scratches rock, leaving striations
The amount/rate of erosion depends on, local geology, velocity of the glacier, weight and thickness of the ice, and the amount of load carried
How are cirques formed
A pre-glacial hollow is enlarged by freeze-thaw and removal of snow melt
Ice accumulates in the hollow
After a critical weight and depth, the ice moves out in a rotational manner, and erodes the floor by plucking and abrasion
Meltwater trickling down allows the cirque to grow by freeze-thaw.
This leaves an armchair shaped hollow, which is usually filled with a lake
How are aretes and pyramidal peaks formed
The recession (cutting back) of 2+ cirques.
How are glacial troughs (U shaped valleys) formed
From a pre glacial valley
They have steep sides and flat floors, and the interlocking spurs from the pre-glacial valley have been shortened
How are hanging valleys formed
Tributary glaciers which do not cut down to the level of the main valley, but are left suspended above. They usually have a waterfall
What is the different between glacial drift and till
Drift- glacial and meltwater deposits left after the ice has melted
Till- Angular, unsorted glacial deposits
What are the characteristics of Till
Poor sorting- it contains a large range of rock sizes
Poor stratification- No regular sorting by size
Mixture of rick types
Many particles have striations
What are erratics
Large boulders, foreign to the local geology
What is moraine
Lines of loose rock
At the snout of the glacier there is a crescent shaped mound called terminal moraine
Lateral moraine is a ride of material found on the edge of a glacier
Where two glaciers merge and the two lateral moraines flow in the middle of the enlarged glacier, it is medial moraine
What is freeze thaw weathering
A process in which water freezes at 0 degrees and expands by 10%. It puts great pressure on jointed rocks. The more freeze thaw cycles a year, the greater the impact.
What is frost heave
Where water which freezes in soil lifts individual particles of soil towards the surface. The stones in turn protect the ice from melting initially, so when the ice under stones finally melts, other particles have fallen back to their original levels, and the stones do not fall back as much
What is solifluction
In winter water freezes in the soil causing expansion of the soil and segregation of individual soil particles. In spring the ice melts and water flows downhill. It cannot infiltrate the soil because of the impermeable permafrost. As it moves over the permafrost the soil becomes separated and are spread downslope
What is patterned ground and how is it formed
A general term describing the stone circles, polygons and stripes which are found in soils which are subjected to intense frost action.
Their exact mode of formation is unclear however frost heave, solifluction and vegetation are all believed to be mostly responsible
What is a pingo
An isolated, conical hill which is found in periglacial environments. They are formed by the movement and freezing of water under pressure.
What is the difference between an open and closed system pingo
Open system- Formed when the source of water is from a distant, elevated source.
Closed system- Formed when the water is local, and the pingo is formed due to the expansion of permafrost
What is thermokarst
Depressions caused by subsidence due to the melting of permafrost. This can be due to
cyclic changes in vegetation which may affect albedo
Shifting of stream channels which may affect the amount of heat affecting permafrost
Fire
What are the 3 types of permafrost
Continuous, discontinuous and sporadic
The active layer of permafrost is found at the surface and it thaws out seasonally
What is salt crystallisation in hot arid environments
Causes the breakdown of rock by solutions of salt. When water on rock evaporates, salt is left behind. As temperatures rise, salts expand and exert pressure on the rock
What is disintegration in hot arid environments
Found where there is a large diurnal temperature range. Rocks heat up during the day, and contract at night. This causes exfoliation of the outer layers of the rock, moisture is essential for this process.
What are the 3 types of river in hot arid environments
Exotic- comes from a different climate zone
Endoreic- Flows to an inland basin
Ephemeral- seasonal
What is deflation as a mode of wind erosion in hot arid environments
The progressive removal of small material, leaving behind larger materials. Forms a stony desert
What is abrasion as a mode of wind erosion in hot arid environments
Erosion carried out by wind borne particles. They act like sandpaper, smoothing surfaces.
How can agriculture in hot, arid areas become more sustainable
Using drought-tolerant crops/fodder for livestock
Reducing herd size to reduce pressure on vegetation
Using animal dung as fertiliser
Building small scale dams
What causes soil infertility in hot arid environments
Low organic content due to limited biomass
Being thin
Lacking in clay
Salinisation which reduces water uptake of plants
Why is mineral extraction in hot arid environments difficult
Most areas are very remote so transport is difficult and expensive
Housing and basic utilities need to be provided
Water shortages may require desalination
Why are periglacial areas fragile
The ecosystem is highly susceptible to human impact due to the limited species involved
The very low temperatures reduce decomposition
Pollution has a very long lasting effect
Permafrost is disrupted by heat
What is desertification
The spread of desert like conditions into previously productive areas. Can be caused by overgrazing and deforestation
What are the consequences of desertification
Environmental
Loss of soil nutrients through wind and water erosion
Changes in composition of vegetation and loss of biodiversity as vegetation is removed
Reduction in land available for crop growth
Economic
Reduced income from pastoralism and food crops
Decreased availability of firewood, necessitating the purchase of oil
Increased rural poverty
Social and cultural
Loss of traditional knowledge and skills
Forced migration due to food scarcity
Social tensions in reception areas for migrants
What are the strategies for preventing desertification
Reducing overgrazing by improving stock quality using vaccination, and better yield varieties
Overgrazing can also be managed by better management and reduced herd sizes
Reducing over cultivation can be achieved by using higher yield varieties, fertilisers, and irrigation.
Finally reducing deforestation is done by social foresting, alternative fuels instead of using firewood, and agroforestry (where farmers continue cropping but use trees to provide shade and fertilise the soil.
What are the environmental effects of climate change in extreme environments
Falling crop yields and rising food insecurity, increased water stress, flooding of low lying areas. Spread of diseases eg. Malaria
Conflict over resources eg. water and pasture. Loss of territory and border disputes, forced migration causing urban overcrowding. Tension over energy supplies
What are some coping strategies for climate change in extreme environments
Improving soil fertility by the careful use of fertilisers
Using indigenous plant species
Improving efficiency of irrigation systems and pest control
Adopting water and soil conservation techniques using stone rows to reduce run-off on slopes
What are some advantages and disadvantages of climate change in extreme environments
Disadvantages
Unpredictable sea ice provides issues for Inuits
More shipping mining and oil and gas exploration may threaten the environment
Advantages
Farming may become more productive as the growing season will extend
Forestry in some areas may become possible
Tourism in cold environments may become more popular
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