Chapter 1Inside the EarthPlate Tectonics

Bell Ringer 1.1

Geologist have used what 2 main types of evidence to learn about Earth’s interior:

Page F6- F7

1. direct evidence from rock samples

2. indirect evidence from seismic waves

Check for understanding

The layers of the earth vary in what 4 ways?

Page F9

1. Size

2. Composition

3. Temperature

4. Pressure

Check for understanding Crust

The crust is a layer of solid rock that includes both dry land and the ocean floor.

1. The oceanic crust consists of what type of rock?

• basalt

2. The continents consists mainly of which type of rock?

• granite

Check for Understanding

MantleThe mantle is made of rock that is very hot. It is divided into three layers based on their physical characteristics. What are the 3 layers of the mantle?

1. Lithosphere (also includes the crust)

2. Asthenosphere (softer, can bend like plastic)

3. The Lower Mantle (solid, extends to the core)

Check for Understanding Core

The core is made mostly of the two metals iron and nickel. What are the two parts of the core?

1. Outer Core (molten metal)

2. Inner Core (solid metal)

Core and the magnetic field

• Outer core moves around the inner core creating a magnetic field.

• https://www.youtube.com/watch?v=WCeSP8bqY1w 3 minutes

• https://www.youtube.com/watch?v=jr7HNZg0ljU peach demonstration from The Core https://www.youtube.com/watch?v=LVkocdkcmAc

Bell Ringer 1.2

What are the four layers of the earth and what are they made of?

Page F10 & notes

1. Crust solid rock

2. Mantle molten rock

3. Outer Core molten metal

4. Inner Core solid metal

Check for UnderstandingHeat Transfer

• What are the three types of heat transfer?

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1. Radiation

2. Conduction

3. Convection

Key Points

• Sunlight is radiation that warms the Earth.

• Radiation = no touching

• Another form of heat transfer by radiation would be the heat you feel from a fireplace.

Key Points

• Conduction is responsible for some of the heat transfer inside the Earth.

• Conduction = touching

• The heated particles of a substance transfer heat through contact with other particles in the substance.

Check for understanding

• Heat is transferred by the movement of currents within a fluid.

• Convection = movement

• Convection is caused by what 2 differences within a fluid?

1. temperature

2. Density (the amount of mass in a volume)

Key point

• When a liquid or gas is heated, it becomes less dense. The particles move faster and spread apart.

• When a liquid or gas is cooled, it becomes more dense. The particles move more slowly and settle together more closely.

• * Convection is caused by differences of temperature and density within a fluid.

Key point

• Gravity also plays a role in creating convection currents.

• Gravity pulls everything toward the Earth’s center. Denser material is pulled harder, forcing less dense material upward. (F=mg)

Check for Understanding

• Without heat what will happen to a convection current?

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• It would stop.

Check for Understanding

• What causes convection currents inside the Earth?

F17

• Heat from the core and the mantle itself causes convection currents in the mantle.

Convection currents in the outer core cause Earth’s magnetic field.

Bell ringer

• Where inside the earth would you find convection currents?

1. Asthenosphere (mantle)

2. Outer core

Drifting Continents

• https://www.youtube.com/watch?v=p0dWF_3PYh4 45 seconds

• https://www.youtube.com/watch?v=ryrXAGY1dmE 1 minute

Mantle convection cells and continental drift

Check for Understanding

Wegener’s hypothesis was that all continents were_____?

Once joined in a single landmass and have since drifted apart. (Pangaea was the supercontinent)

The idea that continents slowly moved over Earth’s surface is known as continental drift.

Check for Understanding

• What evidence did Wegener use to support his ideas about continental drift?

1. Land features (mountain ranges lining up)

2. Fossils (found in places now separate by oceans)

3. Evidence of climate change (fossils of tropical plants found in the Arctic Ocean)

Check for Understanding

• According to Wegener where and how do mountains form?

• At plate boundaries

• The folding of continents push up huge mountains.

• https://www.youtube.com/watch?v=HuSHOQ6gv5Y Himalayas Forming 2 min.

• https://www.youtube.com/watch?v=dXDYoCqwSbM types of boundaries

• Why was Wegener’s hypothesis rejected?

• Wegener could not provide a satisfactory explanation for the force that pushes or pulls the continents.

• Wegener continued to collect evidence on continental drift and update his book He died in 1930 on an expedition to explore Greenland’s continental glacier.

Summary/ Retell

• https://www.youtube.com/watch?v=_5q8hzF9VVE Continental Drift 12 mins

• Terms to know: Continental Drift, Pangea, Fossil

• https://www.youtube.com/watch?v=oOi542f5p0Y watch first 3 minutes. No narration, visual summary.

Bell Ringer

Earth’s Continent

s have moved

?

Shape of Continen

ts?

Earth’s Continent

s have moved

Fossil evidence

Shape of Continen

ts Climate evidence

Mid Ocean Ridges

• Mid-Ocean Ridge: An undersea mountain chain where new ocean floor is produced.

• Figure 15 shows both Deep ocean trenches and Mid Ocean ridges. Sonar was used to map the mid-ocean ridges during WWII.

• What is unusual about Iceland?

• Iceland is a portion of the mid-ocean ridge that rose above sea level. https://www.youtube.com/watch?v=sgDM6m0lUGY (1:23)

Sea Floor Spreading

F25• Harry Hess linked ocean floor ridge system to

continental drift. Maybe Wegener was right! Continents do move. https://www.youtube.com/watch?v=GyMLlLxbfa4 (4 minutes)

• Continually adds new material to the ocean floor.

• Begins at mid-ocean ridge, which forms a crack in the ocean crust. Molten material erupts through the valley, hardens to form the rock of the ocean floor.

Picture Understanding

• Youngest ocean crust is at the mid ocean ridge.

• Oldest ocean crust is at the edges, farthest from the ridge.

Draw this in your notes.

Check for Understanding

• Why is the sea floor spreading?

• Convection currents in the mantle

• How did Harry Hess’ theory about sea floor spreading help prove Wegener’s continental drift theory?

• Ocean floors move like a conveyor belt, carrying the continents along with them.

Check for Understanding

What evidence supports the theory of sea-floor spreading?

1. Molten material (along ridges)

2. Magnetic strips

3. Drilling Samples (age of rocks)

Exit Ticket

• Put these events in order to create a cause/effect chain.

Heat from the core

and mantle

Convection currents

in the mantle

Sea Floor Spreading

Continental Drift

Exit Ticket

• Put these events in order to create a cause/effect chain.

Heat from the core

and mantle

Convection currents

in the mantle

Sea Floor Spreading

Continental Drift