class notes: plate tectonics - mr. leigh-manuell's earth ...earthtoleigh.com/documents/notes/6...

I. Continental Drift

• Continental Drift - ! _____________________________________________________________________

! _____________________________________________________________________________________

• Pangaea - ! ___________________________________________________________________________

! _____________________________________________________________________________________

Alfred Wegener (1915)

• German ___________________ and ____________________

• Proposed the theory of ! __________________________________________________________

• Hypothesized a ! ________________________________________________________________

• Evidence of Continental Drift:

1. ! ______________________________________________________________________________

! ______________________________________________________________________________

2. ! ______________________________________________________________________________

! ______________________________________________________________________________

3. ! ______________________________________________________________________________

! ______________________________________________________________________________

Leigh-Manuell - "1

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

Leigh-Manuell - "2

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

aria

na

Tre

nch

Ton

ga

Tre

nc

h


• 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 - ! __________________________________________________________________

! __________________________________________________________________

Leigh-Manuell - "3

(dots represent earthquake epicenter locations)


• 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 ! _______________________________________

• ! ______________________________________________________________________________

! ______________________________________________________________________________

Leigh-Manuell - "4


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

• ___________________________________________

• ___________________________________________

• ___________________________________________

Leigh-Manuell - "5


• 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

Leigh-Manuell - "6


• Transform Boundary - ! _________________________________________________________________

! _____________________________________________________________________________________

• Example: the San Andreas Fault is 800 km long and runs throughout California

Leigh-Manuell - "7

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

M

aria

na

Tre

nch

Ton

ga

Tre

nc

h


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

Leigh-Manuell - "8


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 - ! ________________________________________________________________________

! _____________________________________________________________________________________

Leigh-Manuell - "9

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


• 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

Leigh-Manuell - "10


• Primary Wave (P-wave)

• ___________________________________________

• Travel through __________________, __________________, and __________________

• Compressional - ! _______________________________________________________________

! ______________________________________________________________________________

• Secondary Wave (S-wave)

• ___________________________________________

• Travel through __________________ only

• Shear - ! _______________________________________________________________________

! ______________________________________________________________________________

• Seismic waves radiate away from the focus

Leigh-Manuell - "11

Shear Wave (S-wave)

Compressional Wave (P-wave)


• 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 __________________

Leigh-Manuell - "12

P-wave Shadow Zone S-wave Shadow Zone


• 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

Leigh-Manuell - "13

24

23

22

21

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

1 2 3 4 5 6 7 8

EPICENTER DISTANCE (× 103 km)

P

9 10

S

TR

AV

EL

TIM

E (

min

)

00


class notes: plate tectonics - mr. leigh-manuell's earth ...earthtoleigh.com/documents/notes/6...

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