Ch.4, Sec.1

1
Ch.4, Sec.1 Inside the Earth
- the Earth is divided into three basic layers
the crust, the mantle the core
- the densest layer is the __________ due to the
immense amount of gravitational pull types of
radioactive elements

• The Crust

• crust the thin and solid outermost layer of the
  Earth above the mantle

- the thinnest layer of the Earth with a width of
3 to 63 miles labeled as continental or oceanic
- mostly made from silicon, oxygen aluminum
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Ch.4, Sec.1 Inside the Earth

• The Mantle

• mantle the layer of rock between the Earths
  crust and core (1,800 miles wide)

- contains most of Earths mass (67) is denser
than the crust

• The Core

• core the central part of the Earth below the
  mantle (2,130 miles wide)

- contains 33 of Earths mass is mostly made
of iron and nickel
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Ch.4, Sec.1 Inside the Earth

• The Physical Structure of the Earth

- the Earth is divided into 5 physical layers
based on physical properties (see pgs. 98 99)

• 1. lithosphere the solid, outer layer of the
  Earth that consists of the crust and the rigid
  upper part of the mantle we call tectonic plates
  (1,800F)

• 2. asthenosphere the plastic layer of the
  mantle on which the tectonic plates move (1,800F)

• 3. mesosphere the strong, lower part of the
  mantle between the asthenosphere the outer core
  (1,800F)

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Ch.4, Sec.1 Inside the Earth

• 4. outer core the liquid layer of the Earth
  below the mantle (6,700F)

• 5. inner core the solid, dense center of the
  Earth, which is 4,000 miles beneath the surface
  (7,800F)

5
The Rock Cycle (pgs.30-31)
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Ch.4, Sec.1 Inside the Earth

• Tectonic Plates

• tectonic plate a block of lithosphere that
  consists of the crust and the rigid, outermost
  part of the mantle

• the Pacific plate is the largest has created a
  large ring of volcanoes around the Pacific Ocean
  called the Ring of Fire

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Ch.4, Sec.1 Inside the Earth

• The Ring of Fire

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Ch.4, Sec.1 Inside the Earth
- tectonic plates completely cover the surface of
the asthenosphere
- plates are normally thicker where continents
are thinner under the oceans

• Mapping the Earths Interior

- seismic waves from earthquakes travel through
the Earth at different speeds (slower through a
liquid faster through a solid)
- seismographs measure the times at which
different seismic waves travel through the
Earths interior
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Ch.4, Sec.1 Inside the Earth
10
Ch.4, Sec.1 Inside the Earth
1. Why do seismic waves travel faster through
solids? __________________________________________
_________
2. Why do seismic waves travel slower through
liquids? _________________________________________
__________
3. Where is the greatest amount of volcanic
earthquake activity? ____________________________
_______________
4. Is the crust more dense under the oceans or
the continents? Why? _____________________________
_________________
5. What two factors cause metamorphic rocks to
form? ____________________________________________
_______