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Plate Tectonics
Evidence for movement and
changes in the geosphere
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There are mountain
ranges, mid-ocean
ridges, divergent
plates, convergent
plates and transform
boundaries.
There is also rift
valleys which means
long large valley
formed where
continent is pulled
apart by forces made
when mantle rises up
beneath the continent.
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Divergent plate
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Transform plate
Flow of matter and energy in Earth
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Thermal Convectionpattern of movement in
fluid caused by heating
from below and cooling
from above. Transfers heat
energy from bottom of
convection cell to the top.
Temperature of Earth
increases with depth and
affects density of materials
The transfer of heat from
Earth’s interior to its
surface drives movements
of Earths crust and mantle.
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Thermal Convection
Sources of Earths internal
heat is the decay of
radioactive elements, original
heat of formation, and the
impact of meteorites in Earths
early history.
Nature of Earth’s Interior
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Made up of four
layers- Inner Core,
Outer Core, Mantle,
and Crust.
Density concerns how
concentrated the mass
in an object or
material is.
Rocks in Earths crust
are less dense than
the rocks in the
underlying mantle.
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Earths layers
Core- the solid innermost part
of the Earth consisting mainly
of iron
Crust- two kinds: oceanic and
continental
Mantle- zone of Earth below
crust and above core
Nature of Earths Interior (cont.)
Layer
Thickness
(km)
Composition
Temp.
(°C)
Density
(g/cm³)
Continental
Crust
30-60
Granite silicate rock
(>60% silica)
20-600
~2.7
Oceanic
Crust
5-8
Basaltic silicate rock
(>50% silica)
20-1300
~3.0
Mantle
2800
Solid Silicate
100-3000
~5
Outer Core
2150
Liquid iron-nickel
30006500
~12
Inner Core
1230
Solid iron-nickel
7000
~12
Plate Tectonics Features
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Oceanic Trenches
There’s also
plate boundaries
and hotspots.
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Continental Accretion
Earthquakes are
evidence of plate
tectonic feature.
Geoscientists Observe Earth
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Eduard Suess was an 1800
geologist
Came up with Contraction
Theory which answered the
question How do mountain
ranges form?
Alfred Wegner was an
1912 German
Proposed the hypothesis
of continental drift
According to him Pangea
broke into separate
continent that moved apart
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Eduard Suess
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Alfred Wegner
Theory of Plate Tectonics
Developed
Tectonics comes from the Greek word
tekton which means builder.
 Plate tectonics refers to the building of the
features on Earths surface due to
deformation caused by plate movements.
 Create mountain ranges, trenches, and rift
valleys at or near plate boundaries.
 Particularly evident around rim of Pacific
Ocean where subduction of oceanic plates
around much of rim results in volcanic
arcs and earthquakes.
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