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EARTH’S INTERIOR AND
PLATE TECTONICS
17.1
SURFACE OF THE EARTH
EARTH’S INTERIOR
Earth is made up of 4 main layers.
Crust
Mantle
Outer Core
Core
CRUST
The outermost and thinnest layer of
Earth.
Oceanic Crust – thinner more dense
crust (4 to 7 km)
Continental Crust – thicker less
dense (20-40 km, 25 miles)
MANTLE
The layer of rock between the
Earth’s crust and its core.
Denser than the crust.
2900 km thick
80% Earth’s volume
CORE
The center of a planetary body.
Outer Core- liquid metal
Inner Core- solid metal
EARTH’S INTERIOR
As you travel inside the Earth, the
temperature will increase.
The higher temperatures are a
result of radioactive isotopes found
in the rocks and layers naturally
decaying
PLATE TECTONICS
The theory made by Dr. Alfred Wegner that
Earth’s surface is made up of large moving
plates.
Pangaea - super continent when continents were
one. (200 million years ago)
PLATE TECTONICS
1.
2.
3.
4.
Evidence supporting the theory:
location of animal remains
the Earth’s appearance (continental drift)
Magnetic alignment of oceanic rocks show
older rocks moving away from oceanic
ridges
Geological formations
250 million years in the future
MOVING PLATES
Lithosphere- the thin outer shell of
the Earth, consisting of the crust and
the rigid upper mantle. (over 30
large pieces)
These pieces are called the tectonic
plates
Move 1 to 16 cm per year
HOW PLATES MOVE
Asthenosphere- the zone of the
mantle beneath the lithosphere
that consists of slowly flowing solid
rock.
The lithosphere “floats” on top of
the asthenosphere.
HOW PLATES MOVE
Convection heat currents from the
Asthenosphere causes the
lithosphere to move.
ASTHENOSPHERE
PLATE TECTONICS
PLATE BOUNDARIES
Three Types:
Diverging Faults
Converging Faults
Transforms Faults
DIVERGING BOUNDARIES
When two plates move apart.
Caused by the rising of hot molten
rock called magma.
Forms mid-ocean ridges, new oceanic
crust (rift valley), and volcanoes
CONVERGING BOUNDARIES
(SUBDUCTION ZONES)
Areas where the lithosphere is diving under each
other. (subduction)
Trenches form between two oceanic plates
(Mariana Trench off of Asia)
Volcanoes, and mountains form when an oceanic
plate and continental plate meet.
Huge continental mountains form when continental
plates collide (Mt. Everest)
CONVERGENCE OF THE NAZCA AND SOUTH
AMERICAN CONTINENTAL PLATES IN PERU.
TRANSFORM FAULTS
When rocks vibrate horizontally past
each other at faults.
Faults
a crack in the Earth created when
rocks on either side of a break move.
Cause earthquakes
San Andrea Fault
EARTHQUAKES AND
VOLCANOES
17.2
EARTHQUAKES
The movement of the Earth’s
lithosphere (tectonic plates) along
transform faults.
Japan, California, and western
coast of South America
experience the most.
WHAT CAUSES EARTHQUAKES?
Pressure builds up between
moving plates causing rocks to
break
This releases energy as seismic
waves.
These waves cause the Earth to
shake.
PARTS OF AN EARTHQUAKE
Focus
is the exact area along the
lithosphere where the earthquake
originates. Causing waves to travel in
all directions.
Epicenter
is the area right above the focus on
the Earth’s surface.
Fault
SEISMIC WAVES
Measured as shock waves
These seismic waves help
scientist understand the
interior of the Earth.
3 types
SEISMIC WAVES
1. Primary Waves ( P-Waves)
 Originate at focus
 Longitudinal vibration
st
 1 wave to reach recording
station
SEISMIC WAVES
2. Secondary waves (S waves)
 Originate at focus
 Move slower
 Transverse vibrations
SEISMIC WAVES
3. Surface Waves
 Are the last waves to register with
seismographs.
 Only move across the Earth’s
surface.
 Circular motion vibrations
 Cause the most destruction
SEISMOLOGY
The science of detecting and
measuring earthquakes
Seismographs instruments used to
measure data from an earthquake.
There is over 1000 stations around
the world
Modern Seismograph
How it works
See in action
SEISMOLOGY
Scientist use the difference in time
between P and S waves to
calculate the distance to the
epicenter.
They need information from at
least three stations to pinpoint the
focus and epicenter of an
earthquake.
THE RICHTER SCALE
a scale that represents the
relative magnitude of an
earthquake.
Does not predict damage it will
cause
30
http://earthquake.usgs.gov/earthquakes/
http://www.cnn.com/2010/WORLD/americas/01/12/haiti.earthquake/index.html
HAITI
SAN FRANCISCO 1918
ALASKA 1964
INDONESIA 2004
http://news.bbc.co.uk/2/hi/asia-pacific/4136289.stm
Indonesia
Google Maps Earthquakes
VOLCANOES
Vent
Any opening in Earth’s crust where
magma reached Earth’s surface.
(lava)
Release molten rock, lava, ash, and
poisonous gas.
TYPES OF VOLCANOES
1. Shield volcano
 Largest volcanoes
 very fluid lava that flows
great distances.
 Eruptions are usually mild.
 Gentle slopes.
Shield Volcano
TYPES OF VOLCANOES
2. Composite
 Lava is much thicker
 traps gases in the magma
 causes the eruptions to be very
violent (most destructive)
 Steeper slopes
 (Mt. Fuji, Mt St. Helens)
MT. VESUVIUS- POMPEI
TYPES OF VOLCANOES
3. Cinder cones
 smallest and most abundant
 gases are trapped
 they erupt violently with lots
of ash.
TYPES OF VOLCANOES
4. Seamounts
 Underwater volcanoes
Seamount erupting
VIRTUAL VOLCANO
virtual volcano review
WHERE DO VOLCANOES OCCUR
75% occur in the Pacific
Ocean (Ring of Fire)
Along divergent and
convergent plate boundaries
MINERALS AND
17.3
ROCKS
STRUCTURE AND ORIGINS OF ROCKS
All rocks are made and composed of
mixtures of different minerals.
-Minerals: are natural, inorganic solid
compounds with a definite chemical
composition and internal structure.
3500 known minerals in Earth’s crust
Rocks and minerals classified by
texture, hardness, color, and density.
FELDSPAR
PYROXENE
MICA
OLIVINE/ “PERIDOT”
DOLOMITE
QUARTZ
CLAY
CALCITE
THREE MAIN ROCK TYPES
Igneous
Sedimentary
Metamorphic
IGNEOUS ROCK
Rock formed physically from cooled
and hardened magma or lava.
As a rock cools minerals crystallize
and grow.
Size of crystals depend on how
long the rock cools
TYPES OF IGNEOUS ROCKS
1. Extrusive igneous rock
 cools on surface of Earth.
 Small mineral crystals
 Basalt, Obsidian
EXTRUSIVE IGNEOUS ROCK
IGNEOUS ROCKS
2. Intrusive igneous rock
 Form by cooling below the
Earth’s surface.
 Larger mineral crystals
 granite
INTRUSIVE IGNEOUS ROCK
SEDIMENTARY ROCKS
Rock formed physically from
the compressed or cemented
deposits of weathered
sediment.
Recycled rocks
Sometimes contain fossils
FOSSILS
SEDIMENTARY ROCKS
They are named according to
the size of the fragments they
contain.
SEDIMENTARY ROCK EXAMPLES
Conglomerate
Rock with pebble
sized fragments
SEDIMENTARY ROCK EXAMPLES
Sandstone
Rock with sand sized
fragments
SEDIMENTARY ROCK EXAMPLES
Mudstone
Rock with fine mud
sized fragments
SEDIMENTARY ROCK EXAMPLES
Shale
Rock with flaky mud
sized fragments
SEDIMENTARY ROCK EXAMPLES
Limestone
Rock with fossils of
organisms that lived in
water
METAMORPHIC ROCKS
Rock chemically formed from
other rocks as a result of being
under tremendous heat and
pressure for a period of time.
New minerals form as a result
METAMORPHIC ROCK EXAMPLES
Marble
Formed from
limestone under heat
and pressure
METAMORPHIC ROCK EXAMPLES
Slate
Formed from
mudstone or shale
under heat and
pressure
ROCK CYCLE- OLD ROCKS WILL
FORM INTO NEW ROCKS P 580
HOW OLD ARE ROCKS?
Principle of Superposition
Oldest will be on the bottom, and
the newest on top.
Useful with sedimentary rock and
dating fossils
Only gives a relative estimate age
PRINCIPLE OF SUPERPOSITION
HOW OLD ARE ROCKS?
Radioactive Dating
most minerals contain material with
radioactive isotopes.
Scientists measure the amount of
radioactive material left in rock sample
and compare to the rate at which the
materials decay.
Gives a more exact age of the rocks.
RADIOACTIVE HALF LIFE DATING
RADIOACTIVE DATING
WEATHERING AND
17.4
EROSION
WEATHERING
Two Types:
Physical
Chemical
PHYSICAL WEATHERING
Process in which rocks are
broken down into smaller pieces
without altering the rock’s
composition.
Ice and plants are two types of
physical weathering
PHYSICAL WEATHERING
When water seeps into rocks and
then expands as it freezes,
breaking the rock.
Roots of plants can grow in
between the wedges, and break
the rocks.
CHEMICAL WEATHERING
Breaking down of rock by
changing its chemical
composition.
(chemical
reaction)
EXAMPLE #1
Badlands (SD) are the result of
chemical weathering
Iron reacting with oxygen
(oxidation) breaking down rock
leaving new red hematite
(Fe2O3) minerals on the surface.
EXAMPLE #2
When CO2 dissolves in water,
Carbonic acid is released
This acid then breaks down the
calcite forming underground
caverns made of CaCO3.
EXAMPLE #3
Acid rain
Precipitation that has an unusually high
concentration of acid in it.
Formed as a result of excess burning of
fossil fuels.
Acid rain is strong enough to chemically
break down rock leaving behind the
remains of rocks.
EROSION
The physical process by which
rock and the products of
weathering are removed.
Weathered material may be
removed by running water, wind,
ice, or gravity.
This has shaped our planet
WATER EROSION
GLACIER EROSION
BEACH EROSION
WIND EROSION
DEPOSITION
Physical process of relocating sediment by laying
eroded material in a different space.