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A R C T I C C I R C L E
E Q U ATO R
T R O P I C O F C A N C E R
T R O P I C O F C A P R I C O R N
L.Titicaca
Great BearL.
Great SlaveL.
GreatLakes
São
Fran
cisco
Amazon
Missouri
Mis
siss
ippi
Rio GrandeYukon Mackenzie
Para
ná
AN
DE
S
AN
DE
S
APPALACHIA
NM
TS.
COA
STR
AN
GES
COAST
MTS.
RO
CK
YM
OU
NT
AIN
S
H u d s o nB a y
B a f f i nB a y
DavisStrai tBeri
ngSt
rait
G u l f o fM e x i c o
G u l f o f A l a s k a
CapeHorn
MidwayIs.
Marshall Is.
Aleutian Is.
Hawaiian Is.
Loyalty Is .Van
uatu
BountyIs.
AntipodesIs .
A u c k l a n dI s .
TungaruTuvalu
Fi j i
MarquesasIs.
TubuaiIs.
TahitiSociety Is.
Samoa
Ton
ga
ChathamIs.
PhoenixIs.
Tuamotu Is.
Cook Is.
L i n eI s .
N e wZ e a l a n d
J u a nF e r n á n d e z
I s .
FalklandIs.
GalápagosIs.
Newfoundland
Bermuda
Azores
Greater Anti l les
Bahamas
G r e e n l a n dMelvil le
I. DevonI.
E l l es m e r e I .
Banks I.V i c t o r i a I .
B a f f i nI .
Lesser Antill
es
(Gi lber t Is .)
A T L A N T I C
O C E A N
P A C I F I C
O C E A N
A T L A N T I C
O C E A N
C H U K C H IS E A
B E R I N GS E A LABRADOR
SEA
GR
EEN
LA
ND
SEA
E A S TS I B E R I A N
S E AB E A U F O R T
S E A
C A R I B B E A NS E A
A M A Z O N B A S I N
LL
AN
OS
PLATEAU OFMATO
GROSSO
AT
AC
AM
AD
ESE
RT
P A M P AS
PA
TA
GO
NI A
SIERRAM
ADRE
S O N O R A ND E S E R T
GREATPLA
INS
N O R T H
A M E R I C A
S O U T HA M E R I C A
C E N T R A L
A M E R I C A
EQUATOR
TROPIC OF CANCER
ARCTIC CIRCLE
THINGS TO LOOK FOR ON THE MAP
Highest point on Earth: Mt. Everest,China/Nepal, 29,035 ft (8,850 m)Map H6Lowest point on Earth: MarianaTrench, Pacific Ocean, 35,840 ft(10,924 m) below sea level Map L8Longest river: Nile, Egypt/Sudan/Uganda, 4,187 miles (6,738 km) Map E7Largest lake: Caspian Sea,Azerbaijan/Iran/Turkmenistan/Kazakhstan/Russian Federation,146,101 sq miles (378,400 sq km)Map F5Largest ocean: Pacific Ocean,63,804,540 sq miles (165,241,000 sq km) Map Q7
CONTINENTSThe seven continents that make up
the world’s land mass are, fromlargest to smallest: Asia, Africa,North America, South America,Antarctica, Europe, and Australia.The polar regions, not completelyvisible on the flat map, surroundthe North and South poles and are
shown on the globes left and below.
Only 29 percent ofthe Earth’s surfaceis land. Thepercentage area ofeach continent isshown here.
Water: 71%
Land: 29%
Asia: 30%
Africa: 20%
NorthAmerica:16.5%
SouthAmerica:
12%
Antarctica:9.5%
Europe:7%
Australia:5%
1
2
3
4
5
6
7
8
9
10
11
12
13
U V W X Y A
Earth’s surface
THE PHYSICAL WORLD
N O P Q R S T
12
MID
-ATLANTIC
RID
GE
EA
ST P
AC
IFIC
RIS
E
PACIFIC-ANTARCTIC RIDGE
SOUTHEAST INDIAN RIDGE
SOUTHWEST INDIA
N RID
GE
MID-I ND
IAN
RID
GEMID
-ATL
AN
TIC
RID
GE
PHILIPPINE PLATE
I N D O - A U S T R A L I A N P L A T E
ARABIAN PLATE
IRANIAN PLATE
A N T A R C T I C P L A T E
A F R I C A N P L A T E
E U R A S I A N P L A T E
P A C I F I C
P L A T ECOCOS PLATE
CARIBBEAN PLATE
NAZCA PLATE
SCOTIA PLATE
S O U T H A M E R I C A N
P L A T E
N O R T H A M E R I C A N
P L A T EJUAN
DE FUCA PLATE
Subduction zoneMid-ocean ridge and faultsCollision zoneUncertain plate boundary
Movementof plate
Volcano
KEY TO MAP
MOVING CONTINENTS
MOVING CONTINENTSTHE CONTINENTS THAT MAKE UP most of the Earth’s land surfaceare always on the move, shifted around by forces deep inside theEarth. This is known as continental drift. Movement, or drift,takes place because of intense heat generated within the Earth.The heat is carried upward where it disturbs the cool, rockysurface, or crust, forcing sections of it, called plates, to move.Each year the continents, parts of the plates, drift nearly half an inch (about a centimeter), some getting closer together, others moving farther apart, some grinding past each other. As this happens, many of the Earth’s natural features are created or changed. INSIDE THE EARTH
The Earth is not a solid ball, but is made up of many different layers. The crust that formsthe continents and the ocean floors is a thinlayer of rock that covers the Earth like a shell.The mantle beneath is 1,864 miles (3,000 km)thick and made of hot rock, some of which ismolten (liquid). At the center is the core, thehot metallic center of the Earth. This is liquid
on the outside and solid on the inside.
IN THE BEGINNINGScientists believe that some300 million years ago all theland on Earth was joined togetherin one “supercontinent” called Pangaea. Itwas surrounded by a giant ocean, Panthalassa. About200 million years ago, as the plates moved, Pangaeabegan to split into two great landmasses, Laurasia inthe north, and Gondwanaland in the south. These wereseparated by the Tethys Sea. As the plates continued tomove, the two landmasses split and moved farther apart,eventually forming the continents on the map below.
Liquidouter core
The hotinner coreis solid
Earth’s crust
Upper mantle
200 million years ago
180 million years ago
65 million years ago
P ANTHALA SSA
TE THYS SE ANORTH
AMERICA
Lowermantle
PA N T H A L A S S A
SOUTHAMERICA
EUROPEASIA
AFRICA
AUSTRALIA
ANTARCTICA
PA
NG
AE
A
L AU R A S I A
GO
N D WA N A L A N DINDIA
The Earth Inside and Out 29
Places & TermsIdentify and explainwhere on the earththese terms would befound.
• continent
• mantle
• magma
• crust
• biosphere
MAKING COMPARISONS Study the diagrams of continental drift on this page. Write a description of the location of the continents in the past in comparison with their current location.
Taking Notes PLACE Review the notes you tookfor this section.
• What are the three basic parts ofthe earth’s interior?
• What are four basic spheresfound on or above the earth?
Main Ideas a. What makes up the
interior of the earth?
b. What makes up thebiosphere?
c. How can the presence of seven continents on the earth’s surface beexplained?
Geographic ThinkingMaking Inferences How dothe earth’s spheres influenceone another? Think about:
• the function of theatmosphere
• the makeup of thebiosphere
See SkillbuilderHandbook, page R4.
CONTINENTAL DRIFT In 1912,Alfred Wegener of Germany presented a new idea about continents—the continental drifthypothesis. It maintained that theearth was once a supercontinentthat divided and slowly driftedapart over millions of years.Wegener called the supercontinentPangaea (from a Greek word mean-ing “all earth”). An ocean calledPanthalassa surrounded it. Thesupercontinent split into manyplates that drifted, crashed intoeach other, and split apart severaltimes before they came to their cur-rent positions. This processoccurred over millions of years.
In the 1960s, scientists study-ing the sea floor discovered thatthe youngest rocks were in themiddle of the ocean, at longcracks in the crust. This suggestedthat the new sea floor was beingadded, pushing the continentsapart. Later in this chapter, youwill learn how the rocks of Earth’ssurface are broken into giantplates that move and continue toshape the earth.
LivingPlanet
EarthInside & Out
PA
N
GA
EA
TethysSea
PANTHALASSAOCEAN
200 million y
NORTHAMERICA A S I A
AFRICASOUTH
AMERICA INDIA
AUSTRALIA
ANTARCTICA
65 million years ago
AmericanPlate
PacificPlate
PacificPlate
EurasianPlate
AfricanPlate Indo-
AustralianPlate
Antarctic Plate
ANTA
ANTARCTICA
NORTHAMERICA A S I A
AFRICA
SOUTH AMERICA
AUSTRALIA
EUROPE
Today
200 million yearsago The super-continent wasnamed Pangaea.An ocean calledPanthalassasurrounded it.
65 million yearsago The super-continent split apartand began movingin different direc-tions. Notice thatIndia broke awayfrom Antarcticaand Australia anddrifted toward Asia.
Today The contin-ents continue todrift even today.