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Earth

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Earth s Interior p. 124-131 Chapter 5.1 Exploring inside the Earth Since we cannot travel deep inside the Earth scientist use evidence to learn about the Earth ... – PowerPoint PPT presentation

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Title: Earth


1
Earths Interior
  • p. 124-131
  • Chapter 5.1

2
Exploring inside the Earth
  • Since we cannot travel deep inside the Earth
    scientist use evidence to learn about the Earth
    interior
  • 1. Direct evidence from rock samples
  • Deepest mine 3.8 kilometers or 6.1 miles
  • Deepest hole dug 12 km or 19 miles
  • 2. Indirect evidence from seismic waves
  • Earthquake waves speed and path

3
2 main layers inside Earth
  • 1. Crust
  • 2. Mantle
  • Core
  • All vary greatly in temperature, size,
    composition, and texture

4
Temperature
  • Temperature- at 20 meters down you begin to feel
    warmth.
  • After that every 40 meters down you go the
    temperature increase 1 C.
  • The heat is from the formation of planet and
    radioactive materials in the Earth.

5
Pressure
  • Increasing Depth Increasing Pressure

6
Crust
  • Outermost layer
  • Includes dry land and the ocean floor
  • It is thickest under high mountains(up to 70 km)
    and thinnest under the ocean(5 km)
  • The average is 40 km thick
  • Crust under ocean is called oceanic crust (mostly
    basaltic rock-heavier)
  • Land crust is called continental crust (mostly
    granitic rock-lighter)

7
Mantle
  • At about 40 km down you cross a boundary into the
    mantle. It is divided into 3 very hot layers
    which together are about 3000 km thick.
  • Lithosphere
  • Asthenosphere
  • Lower mantle

8
Lithosphere
  • Uppermost layer
  • Lithosphere is crust and uppermost mantle
    together.
  • Lithos means stone in Greek and averages
    about 100 km thick.
  • Very rigid

9
Asthenosphere
  • Less rigid
  • Like road tar in the sun it is soft, plastic-like
    and very bendable.
  • Asthenes in Greek means weak
  • Still Solid

10
The Lower Mantle
  • Beneath the asthenosphere, the mantle is solid.
  • Goes all the way to the core.

11
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12
The CORE
  • Made of iron and nickel
  • 2 parts
  • Liquid outer core
  • Solid inner core-squeezed so tightly the atoms
    cannot spread apart to be liquids
  • May also contain oxygen, silicon, and sulfur
  • Together about 3486 km thick

13
Magnetic Field
  • Movement in the liquid outer core forms the
    magnetic field for the Earth.
  • This produces a protective shield around the
    Earth and the whole planet acts as a bar magnet.
  • This means we have a north and south pole.
  • Over the course of history, the poles will
    actually switch

14
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15
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16
Convection and the Mantle
  • p. 132-135
  • 5.2

17
Heat
  • Heat is energy in motion. This means the warmer
    the object the faster the particles are moving or
    the more energy they have.
  • Heat always is transferred from warm to cool.
  • When you open the door in the winter, are you
    letting the cold air in or the warm air out?

18
Types of Heat Transfer
  • Three types of heat transfer
  • Radiation, convection, conduction

19
Radiation
  • Transfer of energy through space with no direct
    contact between the heat source and the object.
  • Examples energy from the sun, flame, fire

20
Conduction
  • Heat transfer between objects in direct contact
    with one another. They must be touching.
  • Example touching a hot stove, cooking on the
    stove, etc.

21
Convection
  • Heat transfer by a movement of fluids (liquid or
    gas)
  • Differences in temp and density can cause
    convection.
  • When something is heated the particles move fast
    and require MORE space, so they spread out. This
    cause the density to decrease.
  • Cooler objects are closer and more dense.

22
Convection currents
  • Is the flow that transfers heat in a fluid
  • Heat rises and cool sinks.
  • This continues as long as heat is added.
  • Also occurs in air
  • Have you ever looked at the pavement on a hot
    summer day?

23
Convection Currents in Earth
  • Heat from the core and the mantle causes
    convection currents in the mantle.

24
Drifting Continents
  • 5.3
  • p. 136-140

25
Continental Drift
  • Early in the 1800s when the first complete maps
    on the Earths surface were being made showing
    all the continents, something was noticed. The
    edges of the continents looked as if they could
    fit together like puzzle pieces.

26
  • Alfred Wegener thought that was no coincidence,
    and wrote the theory that all the continents were
    once joined together and had drifted apart. He
    called this theory the continental drift theory.
  • He believed that 300 million years ago all the
    continents were together and they began to move
    horizontally apart. He called the large landmass
    containing all the continents Pangaea, which
    means All Land.

27
Evidence to back up the theory
  • Wegener gathered evidence to support his theory.
  • He used land features, fossils, and climate
    change.
  • In 1915, he published The Origin of Continents
    and oceans.

28
Land Feature Evidence
  • Mountain ranges lined up on different continents
    South America and Africa.
  • Coal fields in Europe and North America lined up.

29
Fossil Evidence
  • Glossopteris is a fern fossil that has been found
    on several continents africa, South america,
    Australia, Asia(India) and Antartica. Based on
    climate now Some of these ferns could not have
    grown there, also plants could not have traveled
    across oceans.
  • Other fossils of fresh water reptiles had been
    found across oceans and they could not have swum
    those great distances.

30
Climate evidence
  • Climate changes as a continent moves but the
    fossils there remain.
  • Tropical plant fossils have been found in the
    Arctic Circle.
  • Glacier evidence was found in South Africa where
    it is very warm now.

31
Wegeners theory rejected
  • Though some believed him when he was alive, most
    accepted his theory after more evidence was
    discovered after his death in 1930.
  • It was not widely accepted because he lacked
    evidence as to HOW the continents moved.

32
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