Journal

Imagine that you were asked to create a model of Earth today

• What would your model show?

2. 1 Earth: A Unique Planet

Zones of Earth

• Crust• Mantle• Core

Characteristics of the 3 major zones of Earth

1. Crust – Thin outermost zone– 1% of Earth’s mass– Continental & Oceanic crust

2. Mantle – Zone of rock– 2/3 of Earth’s mass– 2 different regions: lithosphere (solid upper region) &

asthenosphere (plastic - flows)– PLASTICITY= ability of a solid to flow

3. Core– Center of Earth– Composed of Iron– Solid Inner core, Liquid Outer Core

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are needed to see this picture.

Pause: Observation of Plasticity

Review: Zones of Earth

How did scientists learn about the layers of Earth?

• Seismic Waves• Reconstruction of changes in Earth’s surface

and magnetic field

Seismic Waves

• Vibrations that travel through Earth

• What causes seismic waves?– Earthquakes– Explosions– Volcanoes– Landslides

Two Types of Seismic Waves

• P Waves– Primary waves– Travel through solids, liquids, and gasses

• S Waves– Secondary Waves– Travel only through solids

Speed and direction of seismic waves reveals thecomposition of Earth’s Interior

• Moho: Boundary between crust and mantle• Shadow Zones: Areas where waves are not

detected or only P waves are observed. – Caused by materials that have different rigidities– Waves bend and change direction

Because seismic waves bend and change direction, looking at how the waves travel from one side of the world to the other, scientists are able to deduce the properties of Earth’s Interior!!!

(Math is useful!!!)

The Earth as a Magnet

• Earth has 2 magnetic poles• Magnetosphere: region of

space that is affected by Earth’s magnetic field

• Source of magnetic field- possibly the iron core of Earth

Next time: We will discuss the changes in the magnetic poles of earth as another clue about Earth’s interior and the processes that drive change on Earth

Gravity

The force of attraction that exists between ALL matter in the universe!

Journal Are you composed of matter?Do you exhibit a gravitational pull on objects

around you????

Law of Gravitation

• The force of attraction between any two objects depends upon their masses and the distance between them.

• JournalHow does the moon’s gravitational pull

influence Earth?

THE END

• Start our Model of Earth !!!!