Description
Crust
Mantle
Liquid Outer Core
Solid Inner Core
Depth (km)
0-40
40-2890
2890-5150
5150-6370
% of Earths Mass
0.4
67.1
30.8
1.7
Density
2800kg/m3
Geology Dictionary
definition.
The thin outermost solid
layer of the earth.
Represents less than
1% of the earth’s
volume, and varies in
thickness from approx
5km beneath the ocean
to 60km beneath
mountain chains.
Zone lying between the
earth’s crust and core,
approx 2300km thick.
The central zone or unit of the Earth. The core is
separated into inner and outer core units. The inner
core is a solid with a radius of about 1220km and
the outer core, which does not permit the passage
of shear waves, is liquid.
Characteristic
Moho discontinuity
(40km)- separates low
density silicates (rich in
Al+K) from high density
silicates (rich in Mg+Fe)
Chemical components
Enriched in incompatible
elements (K/Rb) as well
as lithophile elements,
but a few elements
predominate, especially
in silicate minerals,
while some ore metals
are rare (Cu/Sn).
Because the crust was
formed from material
extruded from the
mantle, it is to be
expected that the mantle
Does not permit the
passage of shear
waves.
The mantle is probably
similar in composition to
garnet, peridotite and it
represents about 84% of
the earth’s volume and
68% of its mass.
Reflects seismic waves
Composed of Fe, with a lighter element, probably
Sulphur, and accounts for 16% of the earth’s
volume and 32% of its mass.
is depleted in crustal
components.
Chemical constituents
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Divisions
Lithosphere- strong,
rocky outer shell of the
solid Earth that
comprises the crust and
uppermost mantle to an
average depth of about
100km forms the
tectonic plates.
O2 – 42%
Ca – 2.4%
Mg – 4%
Si – 28%
Al – 8%
Fe – 6%
Other – 6%
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O2 – 44%
Ca – 2.5%
Mg – 22.8%
Si – 21%
Al – 2.4%
Fe – 6.3%
Asthenosphere- weak,
ductile layer of mantle
beneath the lithosphere
that deforms to
accommodate the
horizontal and vertical
motions of the plate.
Deep mantle- mantle
beneath the
asthenosphere,
extending from about
400km deep to the coremantle boundary (about
2900km deep)
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O2 – 5%
S2 – 5%
Fe – 85%
Ni – 5%
 Fe – 95%
 Ni – 5%