explore the structural layers of Earth

In this presentation you will:

Earth Model

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Introduction

The Earth is somewhat like an onion, in that it is made from lots of different layers.

The different layers are composed of different materials. This gives the Earth some of its characteristics.

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Composition of the Earth

The crust is the outer layer of the Earth, made from solid rock. It is much thinner than the lower layers of the Earth.

Each of the layers has different characteristics.

Crust

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Composition of the Earth

The crust has two main parts:

Continental crust – this forms the continents. Its thickness varies from 20 km to 80 km.

Oceanic crust – the thin crust under the oceans. It is around 10 km thick.

Oceaniccrust

Continental crust

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Composition of the Earth

The mantle is underneath the crust. It is made of rock but, due to intense heat, it behaves like an extremely thick liquid!

The mantle moves very slowly. So slowly in fact that its motion would only be noticeable over hundreds of years.

Mantle

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Composition of the Earth

The mantle has two parts:

Upper mantle – the more solid portion. At the top, the temperature is around 1,000 °C.

Lower mantle – the less solid portion. At the bottom, the temperature is around 3,700 °C.

Upper mantle

Lower mantle

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Composition of the Earth

Below the mantle is the outer core. It is mostly made of iron but, because of the extremely high temperatures, the iron has melted and become liquid.

A solid inner core is suspended in the outer core. Although the temperatures at the core are around 4,300 °C, the pressure is so great that the iron stays solid.

Outer core

Inner core

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Depths

The crust ranges from 10 km to 80 km thick.

The upper mantle is about 670 km thick.

The lower mantle is about 2,130 km thick.

The outer core is about 2,250 km thick.

The inner core is about 2,440 km in diameter.

The thickest parts of the crust are the mountain ranges, while the thinnest are the ocean floors.

Inner core

Outer core

Lower mantle

Upper mantle

Crust

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Structure Regions

The upper mantle and the top section of the lower mantle make up the semi-liquid asthenosphere.

The top of the upper mantle and the crust form the lithosphere – the solid outer layers of the Earth.

LithosphereAsthenosphere

Question 1

Which of the following mostly consists of liquid iron?

A) Crust

B) Mantle

C) Outer core

D) Inner core

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Question 1

Which of the following mostly consists of liquid iron?

A) Crust

B) Mantle

C) Outer core

D) Inner core

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Question 2

“The lithosphere is made up of the crust and part of the lower mantle”.

Is this statement true or false?

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False

Question 2

“The lithosphere is made up of the crust and part of the lower mantle”.

Is this statement true or false?

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Inner coreOuter core

MantleCrust

Drill

12 km

(max)

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Modeling the Planet!

We cannot dig down to the center of the Earth to find out exactly how it’s made. So, models have to be used to represent this information.

Models can be made in a variety of ways:

drawing

mathematically

physical

computer generated

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Predictions

Models can be used to predict future events. This is accomplished by using information from previous events and by applying mathematical probability of events happening again.

This is what is happening when you watch a weather forecast!

A weather model has been used to predict what will happen in the coming hours, days or weeks.

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Predictions

A detailed model of the Earth can be built using scientifically recorded data.

This model can then be used to predict, for example, how the Earth’s magnetic field will change over the coming years.

USGS

Kristian Birkeland's electrical terella (Field-aligned currents)

Examples of geological events are earthquakes and the eruption of volcanoes.

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Predictions

By looking at models of the Earth’s crust, scientists are working towards being able to predict when and where geological events may occur.

USGS

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Visualization

Sometimes it is difficult to understand the scale of a concept. Building a 3D model or drawing a model can make it easier to understand.

For example, a 3D model of Earth’s structure the same size as a soccer ball would require the crust layer to be less than 0.5 mm thick!

0.5 mm thick

Question 3

Why might scientists want to model the structure of the Earth?

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A) To predict future events that relate to movement in the Earth’s crust

B) To make it easier to explain what is going on under the surface

C) To better understand why geological events occur

D) All of the above

Question 3

Why might scientists want to model the structure of the Earth?

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A) To predict future events that relate to movement in the Earth’s crust

B) To make it easier to explain what is going on under the surface

C) To better understand why geological events occur

D) All of the above

In this presentation you have seen:

End

Summary

the structure of the Earth including, inner and outer core, mantle and crust

the layers making the asthenosphere

the layers making the lithosphere

advantages and disadvantages of modeling the natural world