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Unit 4
The Dynamic Crust
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A. The Earth in Cross Section
I.
There are 4 major zones that make up the Earth:
A._Lithosphere_______
: Outer, thinnest layer of the Earth. There
are two types:
1. _Continental_____________
:
__30km (18.6 mi.)__
-Thickness:
Granite_______
-Composition:
-Density: ___2.7g/cm3_____
2.
:
__Oceanic______________
-Thickness: _5km (3.1mi.)__
-Composition: _Basalt______
-Density:
__3.0g/cm3_______
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A. Crust
Ocean
composed of
basalt
Continent
composed of
granite
that is
that is
5 to 6 km
thick
up to 30
km thick
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Mantle
B. _________________:
Found below the crust. Has two
parts:
Asthenosphere
1. _________________:
Upper, “plastic” mantle.
-partially melted material.
2. __________________:
Rest of mantle; actual
Stiffer Mantle
temperature is below the melting point.
NOTE: The boundary between the crust and mantle is called
the __________________
Mohorovicic
________________________,
or MOHO.
Discontinuity
Outer Core
C. _________________:
Only liquid layer of the earth.
Composed mainly of iron.
Inner Core
D. _______________:
Solid, innermost layer of Earth.
Composed mainly of iron and nickel.
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B. Mantle
Asthenosphere
Stiffer
Mantle
is
is
Partially
melted
Not
melted
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C. Outer
Core
Only liquid
layer
composed of
Iron
D. Inner
Core
Solid center
of Earth
composed of
Iron and
Nickel
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B. Crustal Movement
I.
Dynamic Crust
-The crust and outermost part of the Mantle is called the
Lithosphere
_________________
A. The first theory of crustal movement was introduced in
Continental
1915 by Alfred Wegener, and was called _____________
Drift
_____________________________________
--Evidence for this theory include:
match up like a puzzle
1. Continents
_____________________________
2. Correlation of rock layers/fossils:
Rock layers and fossils match up
_____________________________________
on the edges of different continents.
_____________________________________
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3. Mountain chains: ________________
Mountain
chains on different continents match up. So do the
_______________________________________
fossils
found in the mountain chains.
_______________________________________
_______________________________________
4. Climate evidence: _________________
______________________________________
Ice
cores taken from glaciers on different continents match up.
______________________________________
______________________________________
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5. Crustal age: ___________________
The age of oceanic crust matches up at equal distances from
______________________________________
mid-ocean ridges.
______________________________________
B.Sea Floor Spreading: _________________
Theory that the oceanic crust has
______________________________________
been constructed by material from deep within the Earth that
______________________________________
rises and spreads apart the mid-ocean ridges.
Circulation of heated fluid
1. Convection cell: __________________
caused by differences in density. This is what moves the
______________________________________
plates.
______________________________________
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2. Evidence
Rock that is closer to the mida. Igneous Ocean Rocks: ______________
ocean ridges is younger and age increases as distance from the
______________________________________
ridge increases.
______________________________________
______________________________________
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Every 10,000
b. Magnetic Reversal: ________________
years, the Earth’s magnetic field
______________________________________
switches. This can be seen in the
______________________________________
magnetic minerals within the basalt
______________________________________
rock found on the ocean floor.
______________________________________
______________________________________
______________________________________
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Sea Floor
Spreading
driven by
Convection
Cells
evidence
Igneous
Ocean
rocks
Magnetic
Reversal
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II.
that Earth’s lithosphere is made up of
C. Plate Tectonics:States
__________________
a number of solid pieces, or plates, that
__________________________________
move in relation to each other.
Plate Boundaries
2 plates coming together
A. Convergent: ____________________
--3 Types:
Continental-continental
1. __________________________:
Two continental plates
coming together.
Himalayan Mtns. (Indian-Australian and Eurasian Plate
Ex: ______________________________
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II.
Plate Boundaries
A. Convergent
Oceanic-continental
2. ______________________:
Oceanic and Continental
plates coming together.
Island-arc
--Typically will form an _____________
Oceanic trench
along an ________________________
, where the ocean
plate pushes under
the continental plate. _________________
Ex: _____________________________
_______________________________________
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II.
Plate Boundaries
A. Convergent
3. _____________________:
Two ocean plates coming
Continental-Oceanic
together.
Ocean trench
--Typically will form an _____________
as one plate
pushes under the other.
Ex: _____________________________
Peru-Chile Trench (Nazca and
South American Plates
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2 plates moving away from each
B. Divergent: ______________________
other (Sea-floor spreading)
___________________________
-Usually form ____________________
Mid-Ocean Ridges
Ex: ________________________
Mid-Atlantic Ridge (North American and
Eurasian/African Plates
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Plate
Boundaries
Plate
Tectonics
moving
plates
meet at
Convergent
come
together
Examples
ContinentalOceanic
OceanicOceanic
ContinentalContinental
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Plate
Boundaries
Divergent
Move
apart
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I.
Plate Boundaries
2 plates sliding past
C. Transform Fault:___________________
each other
_______________________________________
The Earth is cracked.
-Forms where _____________________
_______________________________________
San Andreas Fault (Pacific and North American Plate
Ex: ____________________________________
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Plate
Boundaries
Transform
Move
Horizontally
Past Each
Other
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C. Evidence of Crustal Activity
I.
Crustal Activity
A. Deformed Rock Strata
--Originally, sedimentary rocks form ____
In horizontal layers called beds
______________________________________
However, observations made of Earth’s surface indicate that
___________________________________________________
The horizontal layers have been changed.
This includes:
Rocks are pushed up at an angle.
1. Tilting: _______________________________________
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2. Folding: __________________________
Bends in the rock layers due to
____________________________________
continental collisions.
Breaks in rocks where plate
3. Faulting: __________________________
movement has occurred.
___________________________________
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B. Displaced fossils: ___________________
Fossils of organisms that lived in the sea
_____________________________________
have been found on mountain tops.
_____________________________________
II. Results of Crustal Activity
A. Earthquakes: _____________________
Any shaking, or rapid motion of Earth’s solid
_______________________________________
outer layers.
_______________________________________
place underground where the
--focus: The
____________________________
earthquake occurs.
_______________________________________
The location at Earth’s surface
--epicenter: _________________________
just above the focus.
_______________________________________
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--Types of earthquake waves:
P-waves
1. __________________:
Also called compressional waves;
the motion of the ground is parallel to the direction of wave
Solids and Liquids
motion. These waves can pass through ______________
__________________________________
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2. _______________:
S-waves
Also called longitudinal waves; the
motion of the ground is perpendicular to the direction of wave
motion. These waves can pass through _____________
SOLIDS ONLY
______________________________________
Surface Waves
3. ________________:
Waves that ripple the surface of the
Earth, causing most of the damage of an earthquake.
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P-waves
--When traveling through the same material, ___________
travel
faster than ____________.
S-waves
speeds in different
-Since these waves travel at different ________
types of
___________
materials, we can use earthquake waves to tell us
about the __________________________.
interior of the Earth.
P-waves
-When an earthquake occurs, both __________
and _________________.
S-waves are given off In many places on Earth, both waves are
received; however, in other places,
only P-Waves are received
_________________________.
-Since S waves cannot pass through a liquid, the conclusion is
some parts of the Earth’s
that _______________________
interior are liquid.
______________________________________
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-If an earthquake occurs under the ocean, the energy is also
released through the ocean water. When it reaches the coastline of
a continent or island, it may form a large, fast moving wave called a
Tsunami
_________________.
500+ mph
They may move at speeds of _________
and may be
____________________high!!!
20-100 feet
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B. Earthquake Strength
-The strength of an earthquake can be determined in one of
two ways:
Richter Scale
1. ______________:
Used to describe the amount of energy
released by an earthquake. It ranges from ___
0 to ___,
10 and
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each increase on the scale indicates a release of ____
times more energy!!!
--To record earthquake waves, seismologists use a
seismograph
_______________,
which can be used to record the arrival
time of the waves and the intensity of the waves.
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Mercalli Scale
2. __________________:
Used to describe the earthquake in
I to
terms of the amount of damage done. It ranges from ___
XII These are based on personal accounts.
___.
--Why is the Richter scale better to use when describing the
intensity of an earthquake, rather than the Mercalli scale?
_________________________
Because the Richter scale uses actual
____________________________________
measurements rather than the Mercalli
____________________________________
scale which uses personal accounts which can
____________________________________
change from person to person.
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C. Volcanoes:
--How do they form?
1. Molten rock from within the earth, called _______, along
with gases, begins to rise up through cracks and weak spots in
the crust.
2. When this molten material, along with gases from inside
earth, break through the surface, it may flow out on the
surface, and then it is called _____.
--Where do they form?
1. __________________________________
_______________________________________
2. __________________________________
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3. __________: Weak points in the crust, located over
unusually high heat flow in the mantle. Although the crust may
move, _____
_______________________________________
_______________________________________
-Ex: ________________________________
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Continental
drift
evidence
puzzle
fit of
continents
correlation
of rock
layers
mountain
chains
climate
evidence
crustal
age
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crustal
activity
deformed
rock
strata
tilting
displaced
fossils
shallow
fossils
at high
elevation
deep fossils
in shallow
water areas
folding
faulting
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results of
crustal
activity
Earthquakes
types
of waves
P waves
S waves
L waves
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Earthquakes
measured
using
Richter
Scale
Mercalli
Scale
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Volcanoes
Shield
Composite
Cinder
erupts
erupts
erupts
lava
lava and
ash
ash and
cinder
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