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Exploring Inside Earth

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Geologists have used two main types of evidence to learn about Earth s interior: Direct evidence from rock samples Indirect evidence from seismic waves. – PowerPoint PPT presentation

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Title: Exploring Inside Earth


1
Exploring Inside Earth
  • Geologists have used two main types of evidence
    to learn about Earths interior
  • Direct evidence from rock samples
  • Indirect evidence from seismic waves.

2
Evidence From Rock Samples Rocks from inside
Earth give geologists clues about Earths
structure. Geologists have drilled holes, or
blasted rock to bring up samples and make
inferences about conditions deep inside the
Earth. These rocks provide more information about
the interior.
3
Evidence From Seismic Waves
  • Geologists cannot look inside Earth. Instead,
    they must rely on indirect methods of
    observation, they use seismic waves.
  • When earthquakes occur, they produce seismic
    waves.
  • Geologists record the seismic waves and study how
    they travel through Earth. The speed of seismic
    waves and the paths they take reveal the
    structure of the planet.

4
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6
The three main layers of Earth are the crust, the
mantle, and the core. These layers vary greatly
in size, composition, temperature, and pressure.
  • Temperature
  • After about 20m of depth the temp. of the rock
    begins to gradually rise toward the center of the
    earth.
  • Pressure
  • As you move closer to the center of the earth
    pressure will gradually increase because the
    amount of rock above you increases.

7
Composition Layers of Earth
  • The crust is the layer of rock that forms Earths
    outer skin. The crust is a layer of solid rock
    that includes both dry land and the ocean floor.
  • Oceanic crust consists mostly of rocks such as
    basalt. Continental crust, the crust that forms
    the continents, consists mainly of rocks such as
    granite.

CRUST
8
  • Earths mantle is made up of rock that is very
    hot, but solid.
  • Scientists divide the mantle into layers based on
    the physical characteristics of those layers.
  • The uppermost part of the mantle and the crust
    together form a rigid layer called the
    lithosphere
  • The part of the mantle just beneath the
    lithosphere is less rigid than the rock above.
    This part of the mantle is somewhat softit can
    bend like plastic. This soft layer is called the
    asthenosphere

9
  • The core is made mostly of the metals iron and
    nickel. It consists of two partsa liquid outer
    core and a solid inner core.
  • The outer core is a layer of molten metal that
    surrounds the inner core. Despite enormous
    pressure, the outer core is liquid.
  • The inner core is a dense ball of solid metal. In
    the inner core, extreme pressure squeezes the
    atoms of iron and nickel so much that they cannot
    spread out and become liquid.

10
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11
The Core and Earths Magnetic Field
  • Scientists think that movements in the liquid
    outer core create Earths magnetic field. Because
    Earth has a magnetic field, the planet acts like
    a giant bar magnet.

12
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