Earth Interior review (seismic waves convection density CER)

Let's talk evidence vs reasoning.

Evidence does not explain, evidence just supports (proves) an explanation.

Let's take a look at some models and what is and is not evidence shown in the model.

Multiple Select

What evidence do you see in the picture?

(ONLY select things that you SEE, not things that you KNOW)

• S-waves can travel through the mantle

• S-waves can't travel through liquid

• P-waves can travel through the mantle, the inner core, and the outer core

• P-waves can go through all states of matter

• P-waves bend when they move from the mantle to the inner core

In the picture you see that P waves are shown with red lines and S waves are shown with blue lines.

​

Evidence in a model is only what can be seen and described.

You see the blue lines go through the mantle but not the inner or outer core.

Evidence in a model is only what can be seen and described.

You can see the red lines going through all layers of the Earth.

Evidence in a model is only what can be seen and described.

You can see that the red lines bend when they move between the mantle and the outer core.

Evidence in a model is only what can be seen and described.

What you can't see on here is what state of matter the mantle is, or what state of matter the core is. The image also does not tell you what P and S waves can and can't travel through.


These are things that you know, but are not included in the picture.

Evidence in a model is only what can be seen and described.

Wave Behavior

Waves can reflect
(bounce)

And refract (bend) due to change in speed or
direction as they travel
through different
materials

This means we also learn things about the matter the wave passes through from what the wave does while traveling.

We can learn from where a wave refracts (bends)

We can learn from where a wave reflects (bounces)

If a wave changes its behavior, and we know another wave didn't hit it, that usually means the matter that the wave was traveling through has also changed.

The wave changed because of the change in matter, so the spot the wave changed is the spot the matter changed.

Multiple Select

Since we know that S-waves can only travel through solids, and we know that P-waves travel through all states of matter, what conclusions can this evidence tells us? Select all.

• The mantle is not solid

• S-waves can't travel through liquid

• The outer core is not solid

• The mantle is solid

• The inner core is not solid

Multiple Select

Since we also know that all waves bend when they change what they travel through, what conclusion(s) could we draw from only looking at the P-waves?

• The mantle is the same as the outer core

• The inner core has a different density than the outer core

• The outer core and the mantle are different

• The mantle is solid

• The inner core is not solid

Heat, Density, & Convection

Multiple Choice

Earth, and the rest of the solar system, formed from a giant cloud of gas and dust in space called a __.

• protosun

• nebula

• galaxy

• comet

Multiple Choice

True or false: the sun heats Earth's atmosphere

• True

• False

Multiple Choice

True or false: the sun heats Earth's surface

• True

• False

Multiple Choice

True or false: the sun heats Earth's interior

• True

• False

Multiple Choice

Where does Earth's internal heat come from?

• The Sun

• The pressure in the Earth

• Gravity

• Residual heat from formation and Radioactive decay

Drag and Drop

As you move from the surface of the Earth to the center, pressure​

Placeholder

. This means​

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also​

Placeholder

.

(you may use words more than once)

Drag these tiles and drop them in the correct blank above

increases

density

decreases

volume

weight

stays the same

Multiple Choice

Which Layer of the Earth has the greatest Temperature, Pressure, and Density?

• Inner Core

• Outer Core

• Mantle

• Convection Zone

• Oceanic Crust

Density = mass ÷ volume

Changing mass or volume without changing both will change your density.

Changing the volume without changing the mass will change the density: you have changed how much room the matter has to move around without changing how much matter you have. This changes how tightly packed the matter is.

The same is true for changing the amount of mass without changing the volume: you have changed how much matter you are packing into a set area.

The Penguin Analogy

You can think of it like penguins on an iceberg.

The amount of penguins you have is your mass.
The size of your iceberg is your volume.
How crowded the penguins are is your density.

The Penguin Analogy

You can think of it like penguins on an iceberg.

If the size of the iceberg changes and the amount of penguins doesn't, how crowded the penguins are will change.

If the number of penguins changes and the size of the iceberg doesn't, then how crowded the penguins are has changed.

If how crowded the penguins are changes but the size of the iceberg doesn't, then the number of penguins must have changed.

Multiple Choice

Which diagram shows the LEAST dense object?

• left

• center

• right

Rising and Sinking

If something is less dense than the matter that surrounds it, it will rise or float in that matter.

​Rising

If something is more dense than the matter that surrounds it, it will sink.

Sinking

Temperature changes density

When matter cools off, it becomes more dense than it used to be.

Cooler

If you warm up a piece of matter, it will be less dense than it used to be.

Warmer

​You have to use the same thing when you are comparing density using temperature: warm water and cool water, hotter rock and less hot rock

​When a flock of penguins is outside on a nice, warm day, the flock will spread out.

This means that flock of penguins is less dense. The amount of penguins did not change: how tightly packed the penguins were changed, so the amount of space the flock took up changed.

Warming up

When a flock of penguins is outside on a very very cold day, the flock will huddle together.

This means that the flock of penguins is now more dense. We still didn't change how many penguins we have, only how much space the flock is using.

Cooling off

​The penguins are going to help here too...

Temperature changes density

The molecules in matter do the same thing.

Cold molecules move less, so they are packed more tightly together. The matter those cold molecules are in is more dense.

Warm molecules move more, so they spread out. This makes the matter less dense.

Multiple Choice

Rocks sink because they are

• the same density as the water

• less dense than the water

• more dense than the water

• colder than the water

Convection Currents in Earth

Inside Earth, heat from the core acts like the stove burner

Heat released from Earth's core drives convection currents throughout the mantle and the crust

There are also convection currents in the outer core that cause Earth's magnetic field- the molten iron moving is what creates the field.

Multiple Choice

In convection, a warm fluid ________, because it is ________ dense.

• rises, less

• sinks, more

• sinks, less

• rises, more

Multiple Choice

Why does warm mantle rock rise above cooler mantle rock?

• it is warmer, so it is less dense

• it is less dense, so it is warmer

• it is warmer, so it is more dense

• it rose up, so it is warmer

Multiple Select

At which point(s) is the temperature of the mantle greater?

• A

• B

• C

• D

Multiple Select

At which point(s) is the density of the material greatest?

• A

• B

• C

• D

Open Ended

What causes the convection cell to turn to the left at point B?

Multiple Choice

What happens to the temperature and density of the material between points B and C?

• The temperature drops, so the density decreases

• The temperature drops, so the density increases

• The temperature rises, so the density increases

• The temperature rises, so the density decreases

Multiple Choice

What causes the convection cell to turn up at point A?

• The temperature drops, so the density decreases

• The temperature drops, so the density increases

• The temperature rises, so the density increases

• The temperature rises, so the density decreases

Multiple Choice

Convection in the mantle is possible because the rock can cool off when it reaches the ________. If the rock cooled at the ________ it would not be able to go anywhere.

• bottom, core

• core, surface

• surface, core

• density, sinks

Convection is why plate tectonics happens. Convection drags the plates.

​Sea floor spreading

The process that continually adds new material to the ocean ​floor while pushing older rocks away from the ridge

This is a divergent boundary between two pieces of oceanic crust.

​What is Sea-Floor Spreading

• By the 1960s, geologists had begun to learn more about mid-ocean ridges

• Mid-ocean ridges add new material to the ocean floor

• Sea Floor Spreading: the process by which new material is added to the ocean floor by mid-ocean ridges​

  • A mid-ocean ridge forms in the oceanic crust

  • Molten material rises up, cools, and hardens

  • Over time, the strips of rock move outward from the ridge

Grade 8 Ohio | Lesion 5.4

Multiple Choice

In seafloor spreading, molten material rises from the mantle and erupts

• along the edges of all the continents.

• along mid-ocean ridges

• in deep-ocean trenches

• at the north and south poles

Multiple Choice

Sea-floor spreading makes

• new oceanic crust

• oceanic trenches

• magma

• new volcanoes

​Evidence for Sea-Floor Spreading: Magnetic Strips

• As molten material cools and hardens, magnetic material in it aligns with the direction of Earth's poles​ at times of eruption

  • Poles can reverse direction, so the magnetic stripes can indicate when molten material erupted

• Magnetic stripes are mirror images on either side of the ridge

​What Happens at Deep-Ocean Trenches?

• The ocean floor does not continue to get wider without stopping

  • Eventually, the ocean floor plunges into underwater canyons

• ​Deep-ocean trenches: deep underwater canyons where the oceanic crust bends downwards

  • The sinking into the mantle of crust takes tens of millions of years​

Grade 8 Ohio | Lesion 5.4

​The Process of Subduction

• Subduction: The process by which the ocean floor sinks beneath a deep ocean trench back into the mantle

• As new material on the ocean floor is created and cooled, it's density changes

  • Initially has a low density when hot, and the density increases as it cools

• While new material cools, it can collide with continental crust

  • Older crust is then pushed down towards the mantle​

Grade 8 Ohio | Lesion 5.4

Multiple Choice

Old oceanic crust is more dense than new oceanic crust because it is

• Hotter

• Cooler

• Taller

• Shorter

Multiple Choice

In seafloor spreading, where is the youngest rock found?

• along the edges of all the continents.

• along mid-ocean ridges

• in deep-ocean trenches

• at the north and south poles

Multiple Select

In seafloor spreading, where is the oldest rock found? Pick two.

• along the edges of all the continents.

• along mid-ocean ridges

• in deep-ocean trenches

• at the north and south poles

Multiple Select

EXIT TICKET: What evidence do you see in the picture?

(ONLY select things that you SEE, not things that you KNOW)

• S-waves can travel through the mantle

• S-waves can't travel through liquid

• P-waves can travel through the mantle, the inner core, and the outer core

• P-waves can go through all states of matter

• P-waves bend when they move from the mantle to the inner core

Open Ended

EXIT TICKET: Please explain the steps of how a convection current happens in the Earth's mantle. Please include the ideas of temperature, density, and sources of Earth's heat in your answer. You may use your entire notebook.

Temperature: 2 points

Density: 2 points

Sources of Earth's heat: 1 pt each, up to 2

Complete explanation of convection in the mantle: 2 points