4.1 EARTH’S FORMATIONDAHS

Mr. Sweet

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OBJECTIVES

Explain how most scientists explain the formation of our solar system.

Describe Earth’s size and shape and the arrangement of its layers.

List three sources of Earth’s internal heat. Describe Earth’s magnetic field.

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NEBULAR HYPOTHESIS

Most widely accepted model for solar system formation

4.6 billion years ago Cloud of gas and dust

rotating in space Shrank due to pull of

gravity, spinning faster Material collected at

center and became hot.

Hydrogen fusion began creating our sun.

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PLANETISMALS

Frictional, electromagnetic, and gravitational forces formed solid particles of ice and rock.

Eventually formed planets and moons.

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OBLATE SPHEROID

A sphere that bulges in the center.

Shape of Earth. Proof

Measuring the weight of object at several places on Earth.

195 Newtons at Poles and 194 Newtons at equator.

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EARTH’S MEASUREMENTS

Total surface area 510 million square

km 55 continental USA’s

149 million square km is above sea level

Ocean covers 361 million square km

29% dry, 71% wet

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ORIGINAL EARTH

Looked like the moon Same material all the

way thru Collisions created

heat Heat melted iron and

nickel Denser material

moved to the center and lighter materials to the surface

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LAYERS OF EARTH

Inner Core Outer Core Mantle

Lithosphere Asthenosphere

Crust

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INNER CORE

Solid iron and nickel

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OUTER CORE

Surrounds the inner core

Composed of liquid iron and nickel

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MANTLE

Thickest of Earth’s layers

Iron, Silicon, and magnesium

Solid High pressure and

temperatures cause it to behave as a liquid.

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CRUST

Thin, rigid layer Lighter rocks

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OTHERS

Lithosphere Crust and uppermost

mantle More rigid material

Asthenosphere Slushlike layer of

mantle Lithosphere floats on

top Cause of plate

tectonics

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EARTH’S HEAT

Meteorite impacts Compression of

Earth’s interior Decay of radioactive

isotopes Slowly losing heat

Differences in rock, crust thickness, and radioactive rock

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TEMPERATURE AT DEPTH

Above 70 feet temperature remains constant year round

Below 70 feet temperature rises 1o Celcius every 40 meters

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MAGNETIC FIELD North Pole is the

positive pole South Pole is the

negative pole Tilted 11O away from

the poles Hypothesized that

the fluid outer core creates the magnetic field Iron moves through

and electric field creating another electric field 16

SECTION REVIEW 4.1

Page 74 Numbers 1, 2, 3, and 4

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