polar region,deserts
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Prepared by:
Chien Yi En
Hong Ee Voon
Terrains
Polar regions
Desserts
Rainforests
Mountains
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Also called as land relief and
topography. It is the vertical and horizontal
dimension of land surface.
Referring to the lie of the land
This is usually expressed in
terms of the elevation, slope,and orientation of terrain
features.
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Terrain affects surface water
flow and distribution.
Over a large area, it can
affect weather and climate
patterns.
Climate zones are
differentiated by
elevation(height).
For example, Weina Degga
(5000 and 8000 Ft between 60
and 85 degrees farenheight)
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Implication for human being
Determines its suitability for human
settlement: flatter, alluvial plains tend to have
better farming soils than steeper, rockier
uplands.
Understanding terrain also supports on soil
conservation, especially in agriculture.
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In terms ofenvironmental quality, agriculture,
and hydrology, understanding the terrainenables the understanding of watershed
boundaries, drainage characteristics, water
movement, and impacts on water quality.
It determines the ability of armed forces to
take and hold areas, and move troops and
material into and through areas. An
understanding of terrain is basic to both
defensive and offensive strategy.
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Determining weather patterns. Two areas
geographically close to each other may differ
radically in precipitation levels or timing
because of elevation differences or a "rain
shadow" effect.
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Rain shadow effect
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Geomorphology
Geomorphology is the study of the formation
of terrain or topography.
Terrain is formed by intersecting processes:1. Geological processes: migration of tectonic
plates, faulting and folding, volcanic eruptions,
rivers.
2. Erosional processes: water and wind erosion,landslides.
3. Extraterrestrial: meteorite impacts.
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1. Geological processes
Migration
of tectonic
plates
faulting
and folding
volcanic
eruptions
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2. Erosional processes
Landslide
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3. Extraterrestrial
METEORITE
IMPACTS
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Do you wonder
what Earth'sPolar Regions are
like?
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Earth's polar regions are the areas of the
globe surrounding the poles also known
as frigid zones.
The North Pole and South Pole being the
centers, these regions are dominated by
the polar ice caps, resting respectively on
the Arctic Ocean and the continentof Antarctica.
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Polar sea ice is currently diminishing, possibly
as a result of global warming.
Sun never rises and sets in summer and in
winter.
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Polar region receive less intensive solarradiation because the sun's energy arrives at
an oblique angle, spreading over a larger area,
and also travels a longer distance through the
Earth's atmosphere in which it may beabsorbed, scattered or reflected.
Since the polar regions are the farthest fromthe equator, they receive the least amount of
sunlight and are therefore frigid.
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Heavy glaciation wherever there is
sufficient precipitation to form permanent ice.
Extreme variations in daylight hours, with 24
hours of daylight in summer, and complete
darkness at mid-winter.
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The northern part of Alaska is the region known
as the Arctic. It is about 80,000 square miles of
tundra, and has a lot of rivers and ponds.
The weather in the winter is -60 C. But the Arctic
Ocean helps to keep things moderate along the
coastal areas. In the summer the temperature is usually cold.
The ground is permanently frozen and during the
summer the soil thaws only a few inches.
It is often windy. It is a hard climate for any
animal to live in, but the Arctic is full of animals.
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This region is the home of the Inupiat
Eskimos. They live by hunting and fishing.
Transportation in this region is mostly by
airplane. In the winter time a lot of people
travel by snow machine and a few people
mush dogs or cross country ski.
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Animals
Polar bears in the Arctic region.
Arctic fox. It is found throughout the Arctic,
usually on tundra. Musk oxen/ muskox
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Herbivores on the tundra include the Arctic
hare, lemming and caribou.
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There are also many birds and marine species
endemic to the colder regions.
wolverines, ermines, and arctic ground
squirrels.
Marine mammals include seals, walrus, and
whales.
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Summer
plants reproduce quickly.
Winter
algae and small animals live underneath thesea ice
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The coldest place on earth
98% of which is covered with snow and ice
very little snow
Devoid of life except for a few lichens and
mosses that cling to rocks
The minimum temperature recorded was -
89,3 C and wind speed until 320 km/h
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Opposite the Arctic region around the North
Pole.
The southern polar region has no permanent
human habitation.
While there are no indigenous human
cultures, there is a complex ecosystem,
especially along Antarctica's coastal zones.
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Land and sea animals
Crustaceans - krill (euphausiids), copepods,amphipods, isopods, crabs, shrimp, sea
spiders, and many others.
Other marine invertebrates - squid, cuttle-fish, octopus, marine snails, sponges, sea
stars, sea squirts, sea anemones, corals.
Insects and Arachnids - Springtails, mites, the
midge Parochlus steineni(the only winged
insect native to the Antarctic), and others.
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Parochlus steineni
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Fish - Antarctic cod, ice fish, crocodile fish,
dragon fish, robber fish, rat-tailed fish, skates,eel-pouts, sea snails, and others
Mammals - Fur seals and whales
Birds - penguins, albatrosses, petrels, prions,
Antarctic fulmar, Antarctic cormorant
Kerguelen cormorant, and South Georgia pipit(the only Antarctic songbird).
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South Georgia pipit
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The Arctic has numerous definitions, includingthe region north of the Arctic Circle currently(Epoch 2010 at 6633'44" N), or the region
north of 60 north latitude, or the region fromthe North Pole south to the timberline.
The Antarctic is usually defined as south of 60south latitude, or the continent of Antarctica.The 1959 Antarctic Treaty uses the formerdefinition.
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Threaten food availability
Resource management and culture for
inhabitants
Inhabitants will also face safety risks as melting
ice causes infrastructure support such as
buildings, roads and pipelines to break down and
traditional hunting grounds become unstable.
Implication to human being
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Why do deserts are concentrated at
appro. 30 N and S latitude?1. Sun shines directly near the equator. The air absorbs moisture
from the equatorial oceans and rises because it is warmer, andtherefore less dense.
2. Rising air cools as pressure decrease. But cool air cannot hold as
much water as warm air, so the water vapor condenses and fallsas rain.
3. This rising equatorial air, which is now drier because of the loss ofmoisture, flows northward and southward.
4. The air cools, becomes denser, and sinks back toward Earths
surface at about 30 north and south latitudes.5. As the air falls, it is compress and becomes warmer, whichenables it to hold more water vapor.
6. As a result, water evaporate from the land surface into the air.Because the sinking air absorb water, the ground surface is dry
and rainfall is infrequent.
1 Wh i t l d i
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Types of deserts:
1) Mountains:
Rain-shadow
deserts
1. When moisture-laden airflows over a mountainrange, it rises. As the airrises, it cools and its abilityto hold water decreases.The water vapor condensesinto rain or snow, which fallsas precipitate on the wind-
ward side.2. This cool air flows down the
leeward side and sinks.
3. The air is compressed and
warmed as it falls and it hasalready lost much of itsmoisture. This warm, dry aircreates an arid zone called arain-shadow desert.
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2. Coastal and interior deserts
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Water and deserts
Water can reach a desert from three sources:
i) Streams flow from adjacent mountains
ii) Groundwater iii) Rain and snow fall
* Rain easily erodes desert soils and it is a factor
in the evolution of desert landscapes.
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1. Desert streams
Desert streams flow for only a short time after
a rainstorm or during the spring, when winter
snows are melting. A streambed that is dry is
called WASH
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2. Desert lakes
During the wet season, rain and streams fill a
desert lake.
During the dry season, inflowing streams may
dry up. An intermittent desert lake is called
playa lake and the dry lake bed called playa.
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Playa
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3. Flash floods
During a rainstorm, a dry streambed may fill
with water so rapidly that a flash flood occurs
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4. Pediments and bajadas
When a steep , flooding mountain streamempties into a flat valley, the water slows
abruptly and deposits most of its sediment at
the mountain front, forming an alluvial fan.
P di d
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Pediments and
bajadas
A bajada is a broad, gently
sloping depositional
surface formed by mergingalluvial fans and extending
into the center of a desert
valley. A pediment is a broad,
gently sloping surface
eroded into bedrock.
Pediment commonly form
along the front of desert
mountains.
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Overall
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The Colorado Plateau
A stream form a canyon by eroding downward
into bedrock. If the down cutting stream
reaches a resistant rock layer, it may erode
laterally, widening the canyon.
Lateral erosion undercuts canyon walls, and
the rock collapses along vertical joints to form
flat topped mesas and buttes.
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SpireButte Mesa
A mesa is smaller than a plateau and is a flat-
topped mountain shaped like a table.
A butte is also a flat-topped mountain
characterized by steep cliff faces and is smaller
and more tower-like than a mesa.
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Wind
Wind will erodes bare,unprotected desert soil.(winderosion)
Wind erosion, called deflation,is a selective process:
1. When wind blows, it removesonly the silt and sand, leaving
the pebbles and cobbles as acontinuous cover of stonescalled desert pavement.
2. Desert pavement preventsthe wind from eroding
additional sand and silt
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In a windstorm, the sand grains bounce overthe ground in a process called saltation.
Windblown sand is abrasive and erodesbedrock. Because wind carries sand close tothe surface, wind erosion occurs near groundlevel.
Salt craking at ground level can also erode thebase of a desert pinnacle.
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Dunes
A dune is a mound or ridge of wind-depositedsand.
How do dunes form????
Wind removes sand from the surface ofdesert deposits the sand at the place wherethe wind slows down.
2nd
: Dunes also form where glacier melted andalong sandy coastlines.A glacier deposits largequantity of bare, unvegetated sediment.
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Dunes are asymmetrical Wind erodes sand
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Dunes are asymmetrical. Wind erodes sand
from the windward side of the dune, carries it
up the dune crest, and then the sand slides
down the sheltered leeward side. Dunes
migrate in the downwind direction. The
leeward face of a dune is called the slip face.
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Dune migration.
Plant vegetation to reduce deflation.
Built artificial wind- breaks
Covering dune with tarry wastes frompetroleum refining.
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1. Fossil dunes
When dunes are burried by younger sedimentand lithified over geologic time,the resulting
sandstone retains the original sedimentary
structures of the dunes
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WIND SPEEDand SAND SUPPLYcontrol the shapesand orientation of dunes.
1. Barchan dunes
The center of the dune grow higher than the edges.When the dune migrates, the edges move fasterbecause there is less sand to trnsport. The resultingbarchan dune is crescent shaped with its tipspointing downwind
Barchan dunes are not connected to one another butinstead migrate independently.
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2. Tranverse dunes
Sand plentiful,evenly dispersed accumulates
in long ridges called tranverse dunes aligned
perpendicular to the prevailing wind.
3 P b li d
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3. Parabolic dunes If sparse desert vegetation is present,the wind
may form a blowout in a bare area among thedesert plants. As sand is carried out of the
blowout, it accumulates in a parabolic dune, the
tips of which are anchored by plants on each side
of the blowout. The tips of parabolic dune pointinto the wind.
Parabolic dunes are common in moist semidesert
regions and along seacoasts.
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4. Longitudinal dunes
If the wind direction is erratic but prevails
from the same direction and the supply of the
sand is limited, then long, straight
longitudunal dunes form parellel to theprevailing wind direction.
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Loess
Wind can carry silt for hundreds, or even
thousands, of kilometers and then deposit it
as loess.
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Deserfication-
Overgrazing, farming, and firewood gathering had causedthe desert expansion. This growth of the desert caused byhuman mismanagement has been called desertification.
i) Heavy animals pack the soil with their hooves, blockingthe natural seepage of air and water.
ii) soil is devoid of vegetation and baked in the sunlight, itbecome impermeable that water evaporates before it soaks
in.Inceased runoff erodes the soil and carries off nutrients. Farmers digging trenches between their fields and fillingthe trenches with manure to absorb water.
Construct stone barriers to slow surface- water runoff.
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Forests cool the air.
Forest shade the soil from the hot sun, treeroots and litter retain moisture.
Evaporation from soil litter combines withtranspiration cooling from leaf surfaces tomaintain cool temperatures when there is norain.
Cool air promotes rainfall rainfall supportsforests
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Dominant plants in the tropical rainforests are
tall trees.
Trees branch only near the top, covering the
forest with a dense canopy of leaves.
Canopy block outs most of the light,only 0.1%
sunlight reaches the forest floor.
The ground in the tropical forest is soggy, tree
trunks are wet, and water drips everywhere.
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Facts.Implication tohuman beings
In tropical rainforests, local rainfall has
decreased when the forests are cut.
When the rainfall decrease wildfire more
forest is destroyed, establishing a negative
feedback mechanism of increasing drought,
fire and forest loss.
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F ld d f lt
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Folds and faults:
Geologic structures
Several factors control How rocks respond to
tectonic stress:
1.The nature of the rock
2.Temperature
3.Pressure
4.Time
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The nature of the rock
Near Earths surface, where temperature and
pressure are low, different types of rocks
behave differently with continuing stress.
Granite and quartzite tend to fracture inbrittle manner.Other rocks, as shale,
limestone,marble tend to deform plastically
Time
Stress applied slowly, favors plastic behavior.
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Temperature
The higher the temperature, the greater the
tendency of a rock to deform in a plastic
manner.
Pressure
High pressure favors plastic behavior. Deeplyburied rocks have a greater tendency to bend
and flow.
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Geologic structures
Geologic structure is any feature produced by
rock deformation. Tectonic stress creates 3
types of structures: folds, faults and joints.
1 F ld1
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1. Folds A fold is a BEND in rock.
3 characteristics of folds:
1.Results from compression
2.Shortens the horizontal distance in rocks
3.Occurs as part of group of many similar folds.
2
3
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A fold aching upward is called anticline and
aching downward is syncline.
The sides of the fold are called the limbs.
Landforms is created by combinations of
tectonic and surface processes
A circular anticlinal structure is called a dome.
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A similar shapes syncline called basin.
F lt
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Faults Fault is a fracture along which rock on one side
has moved relative to rock on the other side
Slip is the distance that rocks on opposite sides of
a fault have moved
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Some faults are a single fracture in rock, some
consist of numerous closely spaced fractures
within a fault zone
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Rocks moves repeatedly along many faults and
fault zones for two reasons:
i) tectonic forces commonly persist in same
place over long periods of time.
ii) once a fault forms, it is easier for rock to
move again along the same fracture than for a
new fracture to develop nearby.
A normal fault forms where tectonic
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movement stretches Earths crust, pulling it
apart. As the crust stretches, the hanging wall
moves down relative to the footwall
The distance between A and A is greater
after normal faulting occurs.
Wedge-shaped block of rock called graben
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dropped downward between a pair of normalfaults
The blocks of rock between the graben thstmoved upward called horsts
Compressive forces may fracture the rock to
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Compressive forces may fracture the rock to
produce a reverse fault. The distance
between points A and A is shortened by thefaulting.
h f l f f l h
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Thrust fault is a type of reverse fault that is
nearly horizontal.
Strike-slip fault is nearly vertical,but
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Strike slip fault is nearly vertical,but
movement along the fault is horizontal
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Joint is a fracture in rock and the rock on
either side of the fracture have not moved. Most rocks near Earths surface are
jointed,BUT joints become less abundant with
depth because rocks become more plastic and
less prone to fracture at deeper levels in the
crust
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1. Tectonic plates drift apart at a divergent
boundary, stretching adjacent rock and producing
normal faults and grabens but little folding of
rocks.
2. At a transform boundary, friction often holds
rock together. The resultant stress may fold, fault,
and uplift nearby rocks. 3. Near a convergent plate boundary,
compression commonly produces large regions of
folds, reverse faults, and thrust faults.
1. Tectonic plates drift apart at a divergent
boundary, stretching adjacent rock and producing
normal faults and grabens but little folding of
rocks.
2. At a transform boundary, friction often holds
rock together. The resultant stress may fold, fault,
and uplift nearby rocks. 3. Near a convergent plate boundary,
compression commonly produces large regions of
folds, reverse faults, and thrust faults.
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Tectonic forces have created mountains
The term OROGENY refers to the process of
mountain building.
Most continental mountain ranges rise because
the crust becomes thicker where tectonic plates
converge.
Tectonic forces have created mountains
The term OROGENY refers to the process of
mountain building.
Most continental mountain ranges rise because
the crust becomes thicker where tectonic plates
converge.
As the lithosphere thickens it also rises
As the lithosphere thickens it also rises
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As the lithosphere thickens, it also rises
isostatically. As the mountain chain grow higher
and heavier, eventually the underlying rockscannot support the weight of the mountains. The
crust and underlying lithosphere then spread
outward beneath the mountains.
At the same time, streams, glaciers, andlandslides erode the peaks as they rise, carrying
the sediment into adjacent valleys.Initially, when
the mountains erode, they become lighter andrise isostatically. Eventually, erosion wins over
isostatic rebound.
As the lithosphere thickens, it also rises
isostatically. As the mountain chain grow higher
and heavier, eventually the underlying rockscannot support the weight of the mountains. The
crust and underlying lithosphere then spread
outward beneath the mountains.
At the same time, streams, glaciers, andlandslides erode the peaks as they rise, carrying
the sediment into adjacent valleys.Initially, when
the mountains erode, they become lighter andrise isostatically. Eventually, erosion wins over
isostatic rebound.
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An island arc is a volcanic mountain chain thatforms where two plates carrying oceanic crustconverge. The convergence causes the older,
colder, and denser plate to sink into themantle, creating a subduction zone and anoceanic trench. Magma forms in thesubduction zone and rises to build submarine
valcanoes. These volcanoes may eventuallygrow above sea level, creating an arc-shapedvolcanic island
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Mountains and Earth
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Mountains and Earth
systemsImplication to human beings
Tectonic forces that originate deep within earthlift mountain ranges. Once mountains rise, theyinteract with the hydrosphere, atmosphere, andbiosphere.
Air rises as it flows across a mountain range.Moisture condenses from rising air to producerain and snow. Rain forms stream that race downsteep hillhides, while snow may accumulate to
form glaciers that scour soil and bedrock. Thusmountains promote precipitation, which erodesmountains.
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References:
The Topic:Polar Regions.http://42explore.com/polar.htm . Accessedon 4 January 2011.
Earth's Polar Regions.http://www.windows2universe.org/earth/polar/polar.html.Accessed on 4 January 2011.
Polar Regions.http://www.globaleducation.edna.edu.au/globaled/go/cache/offonce/pid/3115. Accessed on 4 January 2011.
The polar regions. http://www.barrameda.com.ar/ecology/the-polar-regions.htm. Accessed on 4 January 2011.
http://library.thinkquest.org/3878/ArcticRegion.html. Accessed on
4 January 2011. http://www.geographicguide.com/arctic.htm. Accessed on 4
January 2011.
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