Class Notes: Plate...
Transcript of Class Notes: Plate...
I. Continental Drift
• Continental Drift - ! _____________________________________________________________________
! _____________________________________________________________________________________
• Pangaea - ! ___________________________________________________________________________
! _____________________________________________________________________________________
Alfred Wegener (1915)
• German ___________________ and ____________________
• Proposed the theory of ! __________________________________________________________
• Hypothesized a ! ________________________________________________________________
• Evidence of Continental Drift:
1. ! ______________________________________________________________________________
! ______________________________________________________________________________
2. ! ______________________________________________________________________________
! ______________________________________________________________________________
3. ! ______________________________________________________________________________
! ______________________________________________________________________________
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Class Notes: Plate Tectonics
Name: ___________________________________________ Plate TectonicsDate: __________________________ Period: ___________ The Physical Setting: Earth Science
II. Crustal Activity
• Plate Tectonics - ! ______________________________________________________________________
! _____________________________________________________________________________________
• Plate - ! ______________________________________________________________________________
! _____________________________________________________________________________________
• Lithosphere - ! _________________________________________________________________________
! _____________________________________________________________________________________
• Asthenosphere - ! ______________________________________________________________________
! _____________________________________________________________________________________
• Earth’s surface consists of a dozen major plates and some minor ones
• The plates are moving at rates close to ___________ cm/year
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Peru-Chile
Trench
HawaiiHot Spot
San AndreasFault
Juan deFuca Plate
PhilippinePlate
Aleutian TrenchYellowstone
Hot Spot
North AmericanPlate
AfricanPlateCocos
PlateCaribbean
Plate
Mid
-Atla
ntic
Rid
ge
CanaryIslands
Hot Spot
SouthAmerican
Plate
GalapagosHot Spot
NazcaPlate
AntarcticPlate
Indian-AustralianPlate
PacificPlateFiji Plate
East
Paci
ficR
i dge
AntarcticPlate
Arabian
Plate
EurasianPlate
EurasianPlate
IcelandHot Spot
Eas
tAfr
ican
Rift
Mid-IndianR
idgeSoutheast
Indian RidgeSouthwest
Indian
RidgeScotiaPlate
SandwichPlate
Mid
-Atla
ntic
Rid
ge
Easter IslandHot Spot
St. HelenaHot Spot
BouvetHot Spot
TasmanHot Spot
M
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Class Notes: Plate Tectonics
• Convection Currents - ! _________________________________________________________________
! _____________________________________________________________________________________
• Magma heats up causing it to ___________________ and ____________________
• Magma cools down causing it to ___________________ and ____________________
• The plates are moving on top of the asthenosphere due to density differences
• The idea of continental drift had been around since the 1900’s, but lacked enough scientific evi-dence to support the theory
• New advancements after World War II help provide the evidences needed to validate the Theory of Plate Tectonics
• Earthquake Evidence
• Scientists noticed that earthquakes do not occur at random locations, but throughout the world along __________________________________
• When plotted on a map they outline the ! ____________________________________________
• Volcanic Evidence
• Occurs at plate boundaries where plates are interacting
• Ring of Fire - ! __________________________________________________________________
! __________________________________________________________________
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(dots represent earthquake epicenter locations)
Class Notes: Plate Tectonics
• Rock Evidence
• Sedimentary deposits and igneous lava flows are usually placed down in horizontal layers
• Sometimes movement along boundaries causes these layers to ! ______________________or ________________________
• Mountain Evidence
• As plates collide they sometimes are pushed ! _______________________________________
• ! ______________________________________________________________________________
! ______________________________________________________________________________
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Class Notes: Plate Tectonics
III. Crustal Boundaries
• Tectonic plates are constantly moving and interacting
• As they move across the _______________________________ and form plate boundaries they in-teract in various ways
• Types of plate boundaries:
• ___________________________________________
• ___________________________________________
• ___________________________________________
• Convergent Boundary - ! ________________________________________________________________
! _____________________________________________________________________________________
• Example: the India Plate pushing upward into Eurasian Plate and creating the Himalayan Mountains
• Subduction - ! _________________________________________________________________________
! _____________________________________________________________________________________
• Example: the Nazca Plate being consumed under the South American Plate
• Three Types of Convergent Boundaries
• ___________________________________________
• ___________________________________________
• ___________________________________________
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Class Notes: Plate Tectonics
• Divergent Boundary - ! __________________________________________________________________
! _____________________________________________________________________________________
• Example: part of the Mid-Atlantic Ridge emerges from the ocean and splits Iceland in half
• Sea-Floor Spreading - ! __________________________________________________________
! ______________________________________________________________________________
• Mid-Ocean Ridge - ! _____________________________________________________________
! ______________________________________________________________________________
• Mid-Atlantic Ridge - ! ____________________________________________________________
! ______________________________________________________________________________
• Separates the N. and S. American Plates from the Eurasian and African Plates
• Rift Valley - ! ____________________________________________________________________
! ______________________________________________________________________________
• Divergent Plate Boundary Evidence
• Scientists dragged a ______________________ across the ocean floor and discovered a unique magnetic pattern where stripes of ___________________ and ___________________ polarity parallel the mid-ocean ridge flipping every 200,000 to 300,000 years (the last one was 781,000 years ago).
• Rock samples of the deep ocean floor show that basaltic oceanic crust becomes progressively ____________________ as you approach the mid-ocean ridge
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Class Notes: Plate Tectonics
• Transform Boundary - ! _________________________________________________________________
! _____________________________________________________________________________________
• Example: the San Andreas Fault is 800 km long and runs throughout California
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Peru-Chile
Trench
HawaiiHot Spot
San AndreasFault
Juan deFuca Plate
PhilippinePlate
Aleutian TrenchYellowstone
Hot Spot
North AmericanPlate
AfricanPlateCocos
PlateCaribbean
Plate
Mid
-Atla
ntic
Rid
geCanaryIslands
Hot Spot
SouthAmerican
Plate
GalapagosHot Spot
NazcaPlate
AntarcticPlate
Indian-AustralianPlate
PacificPlateFiji Plate
East
Paci
ficR
i dge
AntarcticPlate
Arabian
Plate
EurasianPlate
EurasianPlate
IcelandHot Spot
Eas
tAfr
ican
Rift
Mid-IndianR
idgeSoutheast
Indian RidgeSouthwest
Indian
RidgeScotiaPlate
SandwichPlate
Mid
-Atla
ntic
Rid
ge
Easter IslandHot Spot
St. HelenaHot Spot
BouvetHot Spot
Key
Complex or uncertainplate boundary
Relative motion atplate boundary
Mantlehot spotDivergent plate boundary
(usually broken by transformfaults along mid-ocean ridges)
Convergent plate boundary(subduction zone)
subductingplate
overridingplate
Transform plate boundary(transform fault)
Tectonic Plates
TasmanHot Spot
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Class Notes: Plate Tectonics
IV. Earth’s Interior
• Earth’s interior structures are known through the study of ! ___________________________________
• Seismic waves refract, _________________________, __________________________ and are ab-sorbed depending on the material they are transmitted through
• Lithosphere - ! _________________________________________________________________________
! _____________________________________________________________________________________
• Continental Crust - ! __________________________________________________________
! ___________________________________________________________________________
• Oceanic Crust - ! _____________________________________________________________
! ___________________________________________________________________________
• MOHO - thin interface separating the lithosphere from the asthenosphere
• Asthenosphere - ! ______________________________________________________________________
! _____________________________________________________________________________________
• Discovery: a decrease in velocity from earthquake waves
• Mantle - ! _____________________________________________________________________________
! _____________________________________________________________________________________
• Outer Core - ! _________________________________________________________________________
! _____________________________________________________________________________________
• Discovery: absorption and refraction of earthquake waves
• Inner Core - ! __________________________________________________________________________
! _____________________________________________________________________________________
• Discovery: an increase in velocity from earthquake waves
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Class Notes: Plate Tectonics
V. Earthquakes
• Earthquake - ! _________________________________________________________________________
! _____________________________________________________________________________________
• Most earthquakes are caused by a movement along a fault where ! _____________________
energy is given off as a seismic wave
• Epicenter - ! ___________________________________________________________________________
! _____________________________________________________________________________________
• Focus - ! _____________________________________________________________________________
! _____________________________________________________________________________________
• Seismometer - ! _______________________________________________________________________
! _____________________________________________________________________________________
• Seismogram - ! ________________________________________________________________________
! _____________________________________________________________________________________
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12.8–13.1
9.9–12.2
3.4–5.6
3.0 basaltic oceanic crust2.7 granitic continental crust
DENSITY (g/cm3)
ATLANTIC OCEAN
NO
RTH
AMER
ICA
MOHO
INN
ER
CORE
(IR
ON
&
NICKEL)
AS
THEN
OSP
HERE(P
LASTICMANTLE)
STI
FFER
MANTLE
OC
EA
NP
AC
IFIC
LITHOSPHERE
}R
IGID
MAN
TLE
CR
US
T
MID-ATLANTIC
RIDGE
OU
TER
CORE
(IRO
N&
NICKEL)
CASCADES
TRENCH
Class Notes: Plate Tectonics
• Mercalli Scale - scale that measures the _______________________ of an earthquake based on the effects to Earth’s surface, humans, objects in nature, and other man-made structures
• The values will differ based on the distance from the epicenter
• ! _________________________________________________________________
• ! _________________________________________________________________
• Richter Scale - logarithmic scale that measures the _____________________________________ re-leased during an earthquake
• Magnitude - a number to quantify the amount of ________________________________ released from an earthquake
• The Richter Scale’s magnitude is determined from the following measurements:
• ! ___________________________________________________________________________
• ! ___________________________________________________________________________
• ! ___________________________________________________________________________
Intensity Type of Damage
I Instrumental
II Feeble
III Slight
IV
V Rather Strong
VI
VII Very Strong
VIII
IX Ruinous
X Disastrous
XI Very Disastrous
XII
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Class Notes: Plate Tectonics
• Primary Wave (P-wave)
• ___________________________________________
• Travel through __________________, __________________, and __________________
• Compressional - ! _______________________________________________________________
! ______________________________________________________________________________
• Secondary Wave (S-wave)
• ___________________________________________
• Travel through __________________ only
• Shear - ! _______________________________________________________________________
! ______________________________________________________________________________
• Seismic waves radiate away from the focus
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Shear Wave (S-wave)
Compressional Wave (P-wave)
Class Notes: Plate Tectonics
• Shadow Zone - ! _______________________________________________________________________
! _____________________________________________________________________________________
• P-waves are ____________________ when they reach the liquid outer core
• S-waves are ____________________ when they reach the outer core and are not transmit-ted through to the other side
• Epicenters are located using the velocity differences between the p-wave and s-wave
• Since the p-waves travel ____________________ then s-waves, as your distance _____________________ from the earthquake's epicenter the arrival time between the two waves will be __________________
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P-wave Shadow Zone S-wave Shadow Zone
Class Notes: Plate Tectonics
• Distance to the epicenter is determined by comparing the arrival times and the E.S.R.T.
• To find the epicenter location you need to triangulate a position using ___________________ differ-ent seismometer stations
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EPICENTER DISTANCE (× 103 km)
P
9 10
S
TR
AV
EL
TIM
E (
min
)
00
Class Notes: Plate Tectonics