polar region,deserts

8/7/2019 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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polar region,deserts

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