Unit 1, Section 3 1

 What are the layers of the Earth?  How do Earth’s internal forces change its surface? 2

1. What is inside the Earth? Cannot dig a hole to the center of the Earth There are extreme conditions in Earth’s interior 3

1. Cannot observe Earth’s interior directly 2. Seismic Waves – results of Earthquakes 3. Geologist study how the waves travel through the Earth 4. Speed of seismic waves and paths they take reveal how the planet is put together 5. Inside the Earth's Interior Inside the Earth's Interior 4

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1. Earth’s interior is made up of layers 2. Each layer surrounds the layers beneath it (like an onion) Q – What kind of indirect evidence do geologist use to study the structure of the Earth? A) Seismic Waves 7

0 M 20 M Several Km Cool Every 40 m = 1°C Increase Rapid Increase in Temperature Increases more slowly, but steadily 8

1. The deeper you go, the greater the pressure Pressure – the force pushing on a surface or area 2. Because of the weight of the rock above, the pressure inside the Earth increases as you go deeper 9

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Crust – a layer of rock that forms Earth’s outer layer 1. Includes rocks, mountains, soil, water that covers the surface of the Earth 2. Relatively thin 3. Includes both dry land and ocean floor 4. Thinnest beneath the ocean 5. Thickest under high mountains 6. Ranges from 5 to 40 km thick 12

Ocean Crust – crust beneath the ocean floor and consist mostly of dense rock like basalt Continental Crust – crust that forms continents and consist mostly of less dense rocks like granite 13

BasaltGranite 14

1. A layer of hot rock, similar to the Crust Lithosphere – uppermost part of the mantle and the crust together form a rigid layer that averages 100 km thick 2. Temperature and pressure increases with depth 3. Making under the lithosphere less rigid than rock above (somewhat like plastic) 15

Asthenosphere – ‘asthenes’ means weak 1. Material is soft and can flow slowly 2. Lithosphere floats on top of the asthenosphere 3. Mantle is 300 km thick Q – How does the material of the asthenosphere differ from materials of the lithosphere? 16

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1. Consist of two parts 1. Liquid Outer Core 2. Solid Inner Core 18

1. The core makes up one-third (1/3) of the Earth’s mass but only 15% of its volume 2. The core is just slightly smaller than the moon 19

Outer Core – a layer of molten metal that surrounds the inner core 1. In spite of enormous pressure, the outer core behaves like a thick liquid Inner Core – A dense ball of solid metal 1. Extreme pressure squeezes the atoms of iron and nickel so much that they cannot spread out and become liquid 20