Transcript Earth`s Interior and Plate Tectonics

Earth’s Interior
and Plate
Tectonics
Earth’s Composition:
•Not just solid rock
•Distinct layers
•Each layer has
certain physical
properties
3 Main Layers when
dividing them by
their composition
►Crust
►Mantle
►Core
Crust
►Outermost
layer
►5 – 100 km thick
►Thinnest layer
►High in Silicon and Oxygen
(makes rocks called silicates)
►< 1% of Earth’s mass
Continental Crust
►Average
thickness
of 30 km
►Composition
similar to granite
Oceanic Crust
►Average
thickness
from 5-8 km
►Composition
similar to basalt
Oceanic crust is
more dense
than
Continental
crust
Mantle
►Between
crust and core
►Extremely thick and
66% (2/3) of Earth’s
mass
►Large amounts of
Calcium and Magnesium
The Core
►33%
(1/3) of
Earth’s mass
►2 separate layers
►Mostly Iron and
Nickel
There are 5 layers when we
divide them up by their
physical properties
►Lithosphere
►Asthenosphere
►Mesosphere
►Outer
Core
►Inner Core
Lithosphere
►Made
of the Crust
and Upper Mantle
►Rigid, solid, cool
►About 150 km thick
Lithosphere is
broken into
tectonic
plates
Asthenosphere
►Upper
part of the mantle
►1-5% liquid rock
►Flows like putty, or plastic
(very viscous)
►Lithosphere (tectonic plates)
slide around on the
asthenosphere
Mesosphere
►The
middle layer when
dividing them up into 5 parts
►Same as the mantle
►About 1% liquid
►High viscosity
►Flows very slowly
Outer Core
►Liquid
layer
►Hot, but not as hot as
the inner core
►Solid
Inner Core
and most dense
layer
o
►6,000 Celsius (hotter
than Sun’s surface)
►So why is it solid?
Some plates
contain both
continental and
oceanic crust
How do we know
what the Earth’s
interior looks
like?
Deepest hole drilled:
►12.2
km into the
earth
►Kola Pennisula,
Russia 1984
Seismic Waves
►From
earthquakes
►There are 3 different types
►Travel through earth’s
layers
►Transmission depends on
phase (density) of the layer
But why do
tectonic plates
move?
Convection Currents
The next time you heat
anything like soup or water
in a pan you can watch the
convection currents move
in the liquid. When the
convection currents flow in
the asthenosphere they
also move the crust. The
crust gets a free ride with
these currents, like the
cork in this illustration.
Dynamics of the mantle…