Chapter 1212.1

Evidence for Continental DriftP. 506-509

Vocabularysupercontinent pangaea continental drift theory continental shelfpaleoglaciation

Continental Drift

Current map of the world:

The world did not always look like this!

Alfred Wegner, a scientist in the 1900’s, began to notice something when he studied the world map: some continents fit together like puzzle pieces. He began to research a bit more into the matter and found a few things:

1. There are the same types of rocks and mountains on different continents.2. There are the same fossils on different continents3. There were very old glaciers all over the world

These observations lead him to come up with the ___________________________1. A very long time ago (~200 million years) the continents were joined together in a

________________________________ called ______________.2. Continents _________ around the world

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Continental Drift

Evidence Notes

1. The shape of the continents

The shape of the continents fit together like jigsaw pieces. the continents fit together even better if we include the

___________________________

2. Matching geological structures

3. Matching Fossils

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4. Paleoglaciation

Some scientists opposed Wegner’s theory of continental drift1. The age of the Earth is debated. Continental drift takes a VERY long time and many scientists believe the

Earth is ________________.2. Wegener could not explain how continental drift occurs. How can huge pieces of land move?

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Chapter 1212.2

The EarthP. 518-522

Geological Structurescrust upper mantle lithosphere rift valleycontinental crust lower mantle asthenosphere subduction zoneoceanic crust outer core spreading ridge trenchmantle inner core

Geological Processesmantle convection seafloor spreading ridge push subductionslab pull

Other Wordsgranite basalt thermal energy

The Layers of the Earth

The Earth is not a solid ball, but made of complex layers. Some of these layers are solid, while others are liquid! Read P. 519-520 and fill in the following table.

Layers Thickness State Main Elements Temperature(oC) Other

The

Crus

t ContinentalRock type:

_____________ (Less dense)

OceanicRock Type:

_____________(More dense)

Man

tle

Upper(lithosphere &

asthenosphere)

Includes the asthenosphere and

part of the lithosphere

Lower

Outer Core rotates

Inner Core very high pressure and rotates

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___________________

state: _________ composition: _______________________ temperature: _______________________

___________________

state: _________ composition: _______________________ temperature: _______________________

___________________

state: __________________ composition: _________________________________ temperature: _____________

__________________Made of tectonic plates that float on the asthenosphere

___________________

state: _______________________ composition: _________________ temperature: __0 - 400°C__

__________________ composition: ________

______________________________________

upper mantle

does not include the crust state: ________________________ composition: __________________

_____________________________ temperature: _____________

mantle

crust

___________________

state: _______________________ composition: _______________________ temperature: __0 - 400°C__

Tectonic Plates

Tectonic plates are like giant pieces of rock floating on top of the ___________ asthenosphere. They float on ____________

there are ______ major tectonic plates and many smaller ones

continents are ____________ to the tectonic plates tectonic plates are always ______________

Convection

Convection is a process where hot material _________ and cool material _________. Tectonic plates are always moving due to convection. They move at a rate of ______________!

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Chapter 1212.1/12.2

Diverging BoundariesP. 523-526

Vocabularydiverging boundary continental plate oceanic plate spreading ridge ridge push seafloor spreading rift valley rift eruption Plate Tectonic Theory mountain range Unifying Theory of Geology

Boundaries

A diverging boundary occurs where two tectonic plates move ________ from each other or are spreading apart. What happens depends on whether the plates involved are _____________ or _____________.

Two Oceanic Plates (under water) Two continental plates (on land)

1. ______________________________________2. The magma _________ and ______________3. ________________: the magma is pushed

aside by new magma coming from below4. The entire process is called seafloor spreading

1. There is a weakened spot on the plate2. _________________________________________

_________________________________________

For both cases, large amounts of magma can be released (called a ___________________) through the crack. This may result in the creation of a _____________.

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Diverging Boundaries/Plates ( ← → )

Plate Tectonics Theory In the mid-1960s, Canadian geologist J. Tuzo Wilson came up with the Plate Tectonics Theory to explain continental drift.

People call the Plate Tectonics Theory the ___________________________________ because it can explain so many things:

how earthquakes happen and why they appear in certain regions how volcanoes are made and why they appear in certain regions how valleys are made and why they appear in certain regions how mountains are made and why they appear in certain regions rock layers why different continents have the same fossil paleoglaciation records on different continents

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Plate Tectonics Theory

1. There are huge slabs of rock called tectonic plates around the world that float on top of partly molten rock (magma in the mantle).

2. Continents are on top of different tectonic plates.3. The tectonic plates move on partly molten rock by _____________________, where old

rock is pushed by new rock.

Chapter 1212.2

Convergent and Transform BoundariesP. 523-526

Vocabulary & Conceptsconverging boundary subduction slab pull trenchfracture fault shield volcano transform boundary

Converging Boundaries/Plates ( → ← ) A converging boundary occurs where two tectonic plates move __________ each other and ___________. What happens depends on whether the plates involved are continental or oceanic.

Continental → ← Continental Convergence

When two continental plate collide: continental plates have similar ______________ the two plates push against each other

Can result in ______________ and _________________ eg. Himalayas are the world’s youngest and

tallest mountain range, and is still growing taller today

Oceanic → ← Oceanic Convergence

When two oceanic plates collide, the ________ more ________ plate will sink under the __________ less dense plate.

the area where the “sinking” occurs is called a _________________________

the subducting plate is pulled down by gravity in a process called ___________

at the subduction zone, there is a deep depression called a ___________o eg. Mariana’s Trench

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Can result in: earthquakes and volcanoes

Oceanic → ← Continental Convergence

Oceanic plates (made of ____________) are heavier and more dense than continental plates the oceanic plate will subduct under the continental plate

Transform Boundaries/Plates (↑↓) A transform boundary occurs where two tectonic plates ________________________ against each other.

usually found near ________________ can be found on land too (San Andreas Fault in California)

Only sliding, no colliding no mountains are formed no composite volcanoes are formed results in breaks or _____________ in rock called ___________

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Can result in: earthquakes, mountains

ranges, and volcanoes

Chapter 1212.2

EarthquakesP. 526-534

Vocabulary & Conceptsearthquake focus epicenter shallow focusintermediate focus deep focus seismic wave primary (P) wavesecondary (S) wave surface (L) wave seismograph seismometerRichter scale perpendicular friction

What is an Earthquake?

Earthquake: shaking of the ground as a result of a ____________________________ in Earth’s crust often occurs as a result of _________ between moving tectonic plates that builds-up ____________ about 80% of earthquakes occur in a ring bordering the ________________________ the Juan de Fuca convergent plate boundary West of Vancouver Island has many earthquakes

Focus: _____________ where the pressure is finally released as an earthquake

Epicenter: the point on the ____________ ____________ _________ the focus

Earthquakes occur at various depths, depending on the plates involved. earthquakes at the surface usually cause more damage

Seismic Waves

Seismic wave: _______________ energy released by earthquakes can tell us the ___________ of an earthquake (where an earthquake happened) can tell us the ____________ of an earthquake

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Classification of EarthquakesClassification Depth of FocusShallow Focus 0 to 70 kmIntermediate Focus 70 to 300 kmDeep Greater than 300 km

Types of Seismic Waves

Seismic Wave Description Ground Motion

Where: ______________________ (body)

Travel through: _________, _____________, and _________Speed: ______________ (~6km/s) When to arrive: _______Direction: ________ direction as the wave’s motion

Analogy: spring

Where: ______________________ (body)

Travel through: _________Speed: _____________ (~3.5km/s) When to arrive: ______ Direction: _________________________ the wave’s motion

Analogy: Rope

Where: _______________________

Travel through: ________Speed: ___________When to arrive: ______________ Direction: _________________________ the wave’s motionCause more _____________________________ than P-waves.

Analogy: Ocean wave

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Measuring Earthquakes

Seismometer: a machine that measures and records seismic wave energy

Seismograph: a graph that shows _______________ of seismic waves how __________ an earthquake lasted an earthquake’s ________________ (strength)

The Richter ScaleThe magnitude (size) of an earthquake is the size of the line on the seismograph

The magnitude is measured by the Richter Scale an increase of ____ in magnitude = _______

stronger

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