G C Flashcards
Sustainability
Social, economic and environmental use of resources in a way that allows future generations to maintain their standard of living.
Arid and semi-arid areas
arid areas receive less than 250mm rainfall per year whereas semi-arid areas receive between 250mm and 500mm per annum
infertility
a lack of nutrients or bases in soils, cause by low weathering rates, a lack of biomass; insufficient nutrients to support arable farming.
periglacial
snow and ice cover on the fringe of glaciated areas (peri = edge) usually associated with permafrost or ground that remains frozen for at least two years. These regions include high mountain and tundra areas of northern Eurasia and North America.
permafrost
permanently frozen subsurface. TO be classified as a permafrost the land must have been frozen for at least two years.
Weathering and erosion
weathering is the breakdown (denudation) of the Earth’s surface in situ (on the spot, that is, without a moving force) whereas erosion is the breakdown of the Earth’s surface by a moving force, for example glaciers, rivers, wind.)
Desertification
the spread of desert or desert-like conditions
Indigenous people
People native to an area and who have been there for many generations.
Resource nationalism
The use of a country’s resources to benefit that country rather than allowing a TNC or another country to benefit from the resources.
polar environments are located? what belt of environments do they have
towards the north pole and the south pole where levels of insolation (solar radiation) are very low)/. in the northern hemisphere there is a belt of periglacial environments, other cold environments are associated with high mountains.
where are desert and semi-arid environments located?
around the tropics and are associated with permanent high-pressure systems which limit the potential rain formation
what are the main factors determining the location of the world’s main deserts?
- high-pressure conditions, for example Sahara and the great Australian deserts
- Continentality - large distance from the sea
- Rain-shadow effects, as in Patagonia in South America and the Gobi desert in central Asia.
- Cold upwelling currents which limit the amount of moisture held in the air.
Disadvantages of mountain areas
difficult areas to build on, they act as barriers to transport, soil are often thin and suffer from high rates of overland run-off and erosion.
periglacial areas - or tundra regions advantages
low temperature produce low rates of evaporation and soils are frequently waterlogged but the growing season is short. Some periglacial areas support large numbers of people and there may be important settlements adjacent to some high-altitude environments
features of desert and semi-arid environments
in areas close to the gulf of aden or the red sea, the lack of water acts as a major constraint for developments. Temperatures are high and in the absence of fresh water the farming is almost impossible. The annual rainfall varies between 250mm and 500mm. Deseret areas may be characterized by a mixture of steep slopes, flat areas, seasonal streams and flash floods.
extreme environments are characterized by
low population densities. for example, three people per square km in central Australia, Iceland and northern Canada. (insufficient heat) Two people per square km in Namibia, and one people per square km in western Sahara. (insufficient water)
indigenous people coping with periglacial environments
indigenous people have turned to river and the oceans since fishing is extremely important in periglacial environments. (Nenets of the Yamal Peninsula in SIbera e.g.)
building on permafrost
engineers rise building above the ground on steel frame so that cold air can flow under them and stop the permafrost from thawing, or thaw the ground first so the structure keeps the ground from freezing.
rainfall in the arid environment
areaas with less than 250 mm rainfall has annual variability of about 50%, flash floods may occur in deserts due to dry surfaces these result in sheet flow (water flowing over large surface areas rather than in distinct channels) and lead to erosion and severe disruption of economic activities
sheet flow
in arid areas where water flowing over large surface areas rather than in distinct channels and lead to erosion and severe disruption of economic activities
when more snow falls (accumulates\an input) than melts (ablates\an output)
the glacier advances
an input - snow falls another from a glacier word
accumulates
an output - snow melts of a glacier another word
ablation
when less snow falls (accumulates\an input) and more melts (ablates\an output)
the glacier retreats
when same amount of snow falls (accumulates\an input) and melts (ablates\an output)
the glacier is steady
the glacier is steady when
accumulation=ablation
glacier retreats when (negative regime)
accumulation<ablation
glacier advances when (positive regime)
accumulation > ablation
pluvials
rainy periods
desertification
due to annual and decadal (in 10 years) variations in rainfall can cause deserts to expand and at other times contract
Glacial erosion methods
plucking and abrasion
plucking (akmens suskilinejimas, atlauzti jo gabaleliai)
this occurs mostly at the base of the glacier and to an extent at the side. it most affective in jointed rocks. As the ice moves, meltwater seeps into the joints and freezes to the rock, which is then ripped out by the moving glacier. Plucking involves downward pressure caused by the weight of the ice and downhill movement. Once the material has been ripped out of the bedrock it can be use din abrasion
abrasion (nubrozdinimai)
that when glacier’s debris scrapes and scratches the rock leaving striations and grooves in the rock. The coarser material will scrape scratch and groove the rock. The finer material will smooth and polish the rock; as ice movement continues, the glacier load will be worn down to form a rock floor.
debris covered glaciers
valley glaciers that have a layer of rocks and sediment on top of the ice surface
factors affecting glacial abrasion
ice thickness
basal water pressure
removal of fine depris
depris particle size and shape
hardness of particles and bedrock
most effective abrasion
when hard particles at the glacier base pass over a soft bedrock
Weathering
is the breaking down or dissolving of rocks and minerals on Earths surface
deposition
when the glacier melts and retreats it leaves behind these rock fragments and sediments in process
a cirque or corrie
an amphitheatre shaped valley that has been scooped out by erosion at the head of a glacier
A lake round
how cirques are formed
- a preglacial hollow is enlarged by nivation (freeze-thaw and removal of snowmelt)
- ice accumulates in the hollow
- having reached a critical weight and depth the ice moves out in a rotational manner, eroding the floor by plucking and abrasion
- meltwater trickles down the bergschrund allowing the cirque to grow by freeze-thaw
nivation
freeze-thaw and removal of snowmelt
bergschrund
a crevasse that forms when the moving glacier ice seperates from the non-moving above)
arêtes and pyramidal peaks (horns)
are cause by the cutting back of two or more cirques.
glacial troughs
u-shaped valleys
hanging valley
they are formed by tributary glaciers which unlike rivers do not cut down to the level of main valley but are left suspended above. they are usually marked by waterfalls.
a roche mountonnée or sheepback
bare mound of rock which is smoothed and polished on their up-valley side (stoss) but plucked on their down-valley side (lee)
glacial deposition characteristics
poor sorting
mixture of rock types
long axis orientated in the direction of glacier flow
striated and subangular particles (visokiu keistu kampu)
moraine
moraine are loose rocks weathered from the valley sides and carried by glaciers.
drumlins
small oval mounds, panasiai kaip smelis susifromuoja kopa, kalniukas, kuris visa deposit sukuria vienoj vietoj
erratics
glacier-transported rock fragments that differ from the local bedrock and may be embedded in till or on the ground surface. they determine the direction of glacier movements.
periglacial areas
found on the edge of glaciers or ice masses
permafrost
periglacial environments are characterized by permafrost which is usually very deep and freezed-thaw action which continuously alters the ground surface so that large quantities of rocks are common
types of periglacial regions
arctic continental alpine
arctic maritime
freeze-thaw
when the temperature fluctuates above or below 0 so the water expands 9-10% and places great pressure on rocks which are broken down to scree (itrukimai toki sakoti mountains)
types of permafrost
continuous -5 to -50
discontinuous -1,5 to -5
sporadic 0 to -1,5
the main factors controlling the depth of the active layer
latitude and altitude
rock type
the nature of the vegetation cover
pingo
they can only develop in periglacial areas
they are the result of the movement of freezing of water under pressure.
open-system and closed-system
thermokarst
caused by the melting of permafrost (fire, climate warming, removal of vegetation.)
patterned ground
stone stripes or garlands on the ground in periglacial areas
weathering in desert types
salt crystallization and disintegration
salt crystallization
which is caused when salts expand and this creates pressure on joints forcing rocks to crack, then the water evaporates, and salt crystals are left behind.
disintegration
rocks heat up during the day but only the surfaces so they peel or exfoliate
river in the deserts are sorted out to (explain)
exotic - they have their source in another wetter environment and then flow through desert (nile)
endorheic - those that drain into an inland lake or sea (jordan river - into dead sea)
ephemeral - rivers that flow seasonally or after storms and have high sediment levels.
wind erosion types and expalin
deflation - removal of small material leaving behind large material
abrasion - the erosion carried out by wind-borne particles. they act like a sandpaper smoothing the surfaces
features of the arid landscape
dunes - an example would be barchan dunes found where sand is limited by there is a constant wind supply.
yardangs and zeugens - wind eroded landforms. zeugens are mushroom shaped resistant layers left and yardangs are long ridges.
wadis
river channels formed by flash floods or wetter pluvial periods
arroyos
river channels that have been enlarged by repeated flooding
solifluction
flowing soil. as water freezes in the soil causing expansion of the soil. in spring the water melts and flows downhill together with the soil.
agriculture in hot arid areas
type of farming in most hot arid areas is nomadism.
they wander with their herds of camels, goats, sheep, etc in search of water. rivers and oases provide opportunities for settled agriculture. For example, the oasis at Douz, Tunisia, produces dates, figs and oranges.
salinization
occurs in areas where annual precipitation is less than 250mm. water evaporates and leaves behind large amounts of salts - it affects the growth of most crop plants by reducing the rate of water uptake by roots and plants die
mineral extraction in hot arid areas
oil and gas in middle east, copper in Chile
difficult because of transportation and expensiveness
negative environmental effects such as - dust for respiratory problems, pollution and risk for the exotic species.
human impact on extreme environments case studies
ski industry
due to climate change and melting of snow covers, skiing resorts are forced to make artificial snow.
mount everest
the road network is rapidly increasing but little attention is paid to safety regulation so it leads to erosion. Due to overcrowded destination, pollution of garbage increases on the mountain’s surface; more garbage raw garbage is taken down to the lower settlements and buried in large pits where inevitably it will threaten the surroundings with toxic leachates.
greenland resource nationalism case study
High natural resource concentration is inaccessible due to snow cover, so melting of snow associated with climate change is beneficial to Greenland but harmful to the world.
oil in libya case study
Oil reserves in Libya are the largest in Africa and are considered highly attractive due to its low cost of oil production. Before the Arab Spring, the production reached over 1.5 million barrels per day but after Arab Spring it significantly decreased. Oil infrastructure has been sabotaged. Groups claiming to be affiliated with ISIS also damaged pipelines and vital equipment. In 2015 attacks by gunmen on oil fields prompted the National Oil Corporation to shut down operations at 11 oil fields.
global climate change advantages
more areas will be able to have agriculture due to temperature increase
in greenland over 90 000 toursits came that stayed in the hotels in 2015
ribbon lake
pailgas lake’as in the walley
Global dimming
is a process by which less direct sunlight reaches Earth’s surface due to aerosol particles, dust, and pollution in the atmosphere that reflect sunlight back into space.
