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Sci. 4-1
Inside the Earth
Pages 88-94
A. The Earth is divided into 3 layers.
1) Crust- outermost layer, thinnest layer
a) 2 types of crust- continental crust
and oceanic crust
b) Oceanic crust is denser than
continental crust
2) Mantle- between the core and crust,
thickest layer
a) molten rock- magma
b) made of mostly iron and
magnesium
3) Core- center of Earth
a) mostly iron
B. The Earth is divided into 5 main physical
layers
1) Lithosphere- outermost layer, rigid,
broken into tectonic plates
2) asthenosphere- soft layer of mantle. It is
a rock that, like putty, flows
3) Mesosphere- lowest part of the mantle,
strong
4) Outer core- liquid part of core
5) Inner core- solid, dense center of Earth
C. Tectonic Plates- pieces of the
lithosphere that move around on top of the
asthenosphere
1)The plates are different sizes.
2) They are made of both continental and
oceanic crusts.
3) Continental crust does not sink below oceanic
crust because the continental crust is less dense
than oceanic crust. Both crusts are less dense
than the mantle, so they float on top of the
asthenosphere.
D. Knowledge about the structure of the
Earth comes from the study of seismic
waves caused by Earthquakes.
1) Seismic waves are vibrations that
travel through the Earth
2) Seismic waves travel faster through
solid rock than liquid.