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Earth as a System:
Earth: A Unique Planet
2.1 and 2.2
Page 27
Unique facts
Only planet with liquid water on the
surface
Atmosphere has a large percentage of
oxygen
Only planet to support life
Earth basics
Third planet from the sun
4.6 billion years old
Mostly made of rock
71% covered with liquid water
Earth from Space
A blue sphere with
white clouds
It is an oblate
spheroid
Spinning made the
polar regions flatten
and have an
equatorial bulge
Relatively smooth
Earth’s Interior
Seismic waves
have shown that
Earth’s interior is
layered
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Layers of the Earth
Earlier you learned about crust,
mantle, and core
Here are some new terms
Look over only
Old Terms
Crust
Mantle
Core
Outer
Inner
New Terms
Lithosphere
Crust and upper solid
mantle
Asthenosphere
Flows with plasticity
Mesosphere
Strong lower part of the
mantle
Core
Outer
Inner
Compositional &Structural Zones
The Earth’s interior can be divided into
compositional and structural zones.
Compositional—What they are made of
Structural—how they behave
Compositional zones are
Crust
Mantle
Core
Structural Zones
Lithosphere
Asthenosphere
Mesosphere
Outer Core
Inner Core
Compositional layers
Crust
thin, solid,
uppermost zone of
Earth.
The crust varies
from thin on the
ocean floor
to thick at the
mountain
ranges
The crust is 10km thick under the
oceans
Made of basalt
Continental crust is between 20-60 km
thick
Made of granitic rocks that are less dense
than basalt
Crust Thickness
The crust is the uppermost
part of the lithosphere
Earth's Internal Layers
Andrija Mohorovičić studied
seismograms and discovered waves pick
up speed at a certain depth
Earth is layered
Drew a map of the upper boundary of
Earth's mantle, Mohorovičić
discontinuity
Cool geologists call it the
The Mantle
3000 kilometers thick
2/3 of Earth’s mass
Hot iron-rich silicate rocks
Core
The center of the Earth
Made of iron and nickel
Structural Zones
Lithosphere
Narrow layer
Includes the Crust
and Upper Mantle
The Upper Mantle is
cool and brittle
The lithosphere is
very narrow and is
rigid and brittle.
It floats on the
asthenosphere.
The lithosphere is
less dense
Asthenosphere
Below the lithosphere is a less rigid
layer called the asthenosphere
It is made of hot, iron-rich silicate rocks
Because of the intense heat and
pressure it behaves with plasticity
It is a solid that flows like a liquid
Thermal convection
currents occur here
Convection currents:
hot less dense material rises, cools, and
begins to fall again.
Mesosphere
The strong lower
part of the mantle
Literally –the middle
sphere
Lies between the
asthenosphere and
outer core
The core is still the core.
The core has two
parts:
the inner and
outer cores
Outer core: liquid
iron and nickel
Inner core: Solid
iron, nickel, &
sulfur
Magnetic Field
When a magnetic
material rotates with
another magnetic
material an electric
current is generated
This current
generates an electric
field
The Earth's inner core spins
within the liquid outer core
producing a magnetic field
Magnetosphere
Earth’s Gravity
Gravity is the force of
attraction that exists
between all matter in
the universe
Newton described his
Universal Law of
Gravitation
The force of attraction
between any two
objects depend on
both their mass and
the distance
between them
Weight and Mass
Weight is the measure of the strength of
the pull on an object (a measure of
gravitational force)
Mass is the amount of matter in an object
There is a difference
Mass stays the same, weight varies
depending on where you are
An object’s weight
depends on its mass
and its distance from
the center of the
Earth
According to the law of
gravitation, the force of
gravity decreases as
the distance from the
Earth’s center
increases