Physical Geography

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Physical Geography A Living Planet
The geography and structure of the earth are
continually being changed by internal forces,
like plate tectonics, and external forces, like
the weather.
Iguaçu Falls at the ArgentinaBrazil border has
275 separate waterfalls, and is nearly three
times wider than Niagara Falls.
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Physical Geography Looking at the Earth
The Earth Inside and Out
SECTION 1
SECTION 2
Bodies of Water and Landforms
SECTION 3
Internal Forces Shaping the Earth
SECTION 4
External Forces Shaping the Earth
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The earth is the only habitable planet in the
suns solar system.
The drifting of the continents shaped the world
we live in today.
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SECTION
The Earth Inside and Out
1
Earth
Continental Puzzle The seven continents on
earth fit together like a jigsaw puzzle
Continentslandmasses above water on Earth
Francis Bacon (1620) first to suggest 7
continents were once one
Map
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The Solar System
The Earths Neighborhood Earth is third planet
in the solar system of the sun Sun is
medium-sized star at edge of the Milky Way
galaxy The solar system includes - sun and
nine known planets - cometsicy spheres
orbiting the sun - asteroidslarge chunks of
rocky material orbiting the sun
Chart
Interactive
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SECTION
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The Structure of the Earth
Matters of Size Circumference of the earth
about 24,900 miles Diameter of the earth about
7,900 miles
Inside the Earth The core is the center of
the earth made up of iron, nickel Outer core
is liquid inner core is solid The mantle
surrounds the core - has several
layers - contains most of Earths mass
Interactive
Continued . . .
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SECTION
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continued The Structure of the Earth
Inside the Earth Magmamolten rock that forms
in the mantle Crustthin layer of rock at
Earths surface
On and Above the Earth Atmosphere is the layer
of gasses surrounding the earth - contains
oxygen - protects Earth from radiation, space
debris - is the medium for weather and climate
Continued . . .
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continued The Structure of the Earth
On and Above the Earth Lithospheresolid rock
portion of Earths surface, forms ocean floor
Hydrospherewater elements on Earth including
atmospheric water Biosphereatmosphere,
lithosphere, hydrosphere combined Plants and
animals live within biosphere
Continued . . .
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SECTION
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continued The Structure of the Earth
Continental Drift Continental Drift1912
hypothesis of Alfred Wegener Earth once one
supercontinent Wegener calls it Pangaea, all
earth Pangaea splits into many plates that
slowly drift apart
Map
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Water covers about three-fourths of the earths
surface.
The earths surface displays a variety of
landforms.
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SECTION
Bodies of Water and Landforms
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Bodies of Water
Ocean Motion The ocean circulates through
currents, waves, tides Currents act like
rivers flowing through the ocean Waves are
swells or ridges produced by winds Tides are
the regular rising and falling of the
ocean - created by gravitational pull of the
moon or sun Motion of ocean helps distribute
heat on the planet - winds are heated and cooled
by ocean water
Continued . . .
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SECTION
2
continued Bodies of Water
Hydrologic Cycle Hydrologic Cyclecycle of
water between atmosphere, oceans, earth
Chart
Lakes, Rivers, and Streams Lakes hold more
than 95 of the earths fresh water Freshwater
lakes, like the Great Lakes, are result of
glacial action Saltwater lakes form when
outlet to sea is cut off - streams and rivers
carry salts into lake - salts build up with
nowhere to go
Image
Continued . . .
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SECTION
2
continued Bodies of Water
Lakes, Rivers, and Streams Rivers and streams
carry water to and from larger bodies of water
Tributaries are smaller rivers, streams that
feed into larger ones Drainage basinarea
drained by river and its tributaries
Ground Water Ground waterwater held in the
pores of rock Water tablelevel at which the
rock is saturated
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SECTION
2
Landforms
Landforms Landforms are naturally formed
features on Earths surface
Oceanic Landforms Continental shelfsea floor
from continents edge to deep ocean Sea floor
has ridges, valleys, canyons, plains, mountain
ranges Islands are formed by volcanoes, sand,
or coral deposits
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Internal forces reshape the earths surface.
Internal forces shaping the earth often
radically alter the lives of people as well.
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SECTION
Internal Forces Shaping the Earth
3
Landforms
Continental Landforms Reliefdifference in
landform elevation from lowest to highest point
Four categories of reliefmountains, hills,
plains, plateaus Topographythe configurations
and distribution of landforms Topographic map
shows vertical dimensions, relationship of
landforms
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SECTION
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Plate Tectonics
The Earth Moves Tectonic plates are massive,
moving pieces of Earths lithosphere Plates
ride above circulating, heated rock  
Geographers study plate movements to
understand - how the earth is reshaped - how
earthquakes and volcanoes are formed
Interactive
Plate Movement   Plates move in one of four
ways - by spreading, or moving
apart - subduction, or diving under another
plate - collision, or crashing
together - sliding past each other in a shearing
motion
Continued . . .
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SECTION
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continued Plate Tectonics
Plate Movement Movement of plates effects
surface of the earth Saudi ArabiaEgypts
plates are spreading apart, widening Red Sea
Indias plate is crashing into Asian
continent, building up Himalayas Three types
of boundaries mark plate movement - divergent
boundary - convergent boundary - transform
boundary
Chart
Chart
Chart
Continued . . .
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SECTION
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continued Plate Tectonics
Folds and Faults Two plates meeting can cause
folding, cracking of rock Fault occurs when
pressure causes rock to fracture, or crack
Fault line is place where plates move past
each other
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SECTION
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Earthquakes
The Earth Trembles An earthquake occurs when
plates grind or slip at a fault line A
seismograph detects earthquakes and measures the
waves they create
Earthquake Locations Location in the earth
where an earthquake begins is called the focus
Epicenterthe point directly above focus on
the earths surface Nearly 95 of earthquakes
occur at tectonic plate boundaries
Continued . . .
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SECTION
3
continued Earthquakes
Earthquake Damage Earthquakes release energy
in the form of motion, causing - landslides -
land displacement - fires (broken gas
lines) - collapsed buildings Richter
Scalenumeric scale showing relative strength
of earthquake
Image
Image
Tsunami Tsunami, a giant ocean wave, begins at
epicenter of an earthquake - travels at up to
450 mph - waves of 50100 ft. or higher
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SECTION
3
Volcanoes
The Explosive Earth Volcanounderground
materials pour from crack in the earths surface
Most volcanoes occur at tectonic plate
boundaries
Volcanic Action Eruptionlava, gases, ash,
dust, explode from vent in Earths crust
Lavamagma that has reached the earths
surface may create landform
Image
Continued . . .
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SECTION
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continued Volcanoes
Ring of Fire Ring of Firezone around rim of
Pacific Ocean - meeting point of eight tectonic
plates - vast majority of the earths active
volcanoes located here Hot spots are where
magma rises to surface from mantle Hot
springs, geysers indicate high temperatures in
earths crust Some volcanic action is
useful - volcanic ash produces fertile
soil - hot springs are tapped for heat, energy
Map
Image
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Wind, heat, cold, glaciers, rivers, and floods
alter the surface of the earth.
The results of weathering and erosion change
the way humans interact with the environment.
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SECTION
External Forces Shaping the Earth
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Weathering
Altering the Landscape Weatheringprocesses
that alter rock on or near the earths surface
Can change landscapes over time and create
soil for plant life Sedimentmud, sand, silt
created by weathering processes
Mechnical Weathering Mechanical
weatheringprocesses that break rock into smaller
pieces Does not change rocks composition,
only size Examples frost, plant roots, road
construction, mining
Continued . . .
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SECTION
4
continued Weathering
Chemical Weathering Chemical
weatheringinteraction of elements creates new
substance Example when iron rusts it reacts
to oxygen in air and crumbles Warm, moist
climates produce more chemical weathering than
cool, dry
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Erosion
Weathered Material Moves Erosionwhen
weathered material moves by winds, water, ice,
gravity - movement grinds rock into smaller
pieces, carries to new location Example
water carries topsoil from hill to river, river
narrows
Water Erosion Most streams erode vertically
and horizontally - a valley cut by a stream
gets deeper, wider forms v-shaped valley - a
river deposits sediment at ocean,
creates deltafan-like landform
Image
Continued . . .
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SECTION
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continued Erosion
Wind Erosion Wind transports sediment from one
place to another Loesswind-blown silt and
clay sediment produces fertile soil  
Glacial Erosion Glacierlarge, long-lasting
mass of ice forms in mountainous areas
Glaciationchanging of landforms by slowly
moving glaciers Example cutting u-shaped
valleys in land Morainehill or ridge formed by
rocks deposited by glacier
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SECTION
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Building Soil
Soil Formation Soilloose mix of weathered
rock, organic matter, air, water Soil supports
plant growth fertility is dependent on three
factors - texture - amount of humus, which is
organic material in soil - amount of air and
water
Continued . . .
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SECTION
4
continued Building Soil
Soil Factors When geographers study soil, they
look at five factors - parent materialthe
chemical composition of the original
rock - reliefthe steeper the slope, the greater
erosion less soil made - organismsplants,
worms, ants, bacteria loosen soil supply
nutrients - climatehot, cold, wet, dry climates
produce different soils - timeabout 2.5 cubic
cm. of soil produced each century
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