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Earth’s Interior Notes
The Four Layers
• Crust
• Mantle
• Outer Core
• Inner Core
• Based on
different
densities
Layer Composition Thickness State of matter
Crust Continental – Granite
Oceanic – Basalt
(lowest density)
Continental- 25 miles
Oceanic – 3-5 miles
(Thinnest Layer)
Solid rocks
Mantle Magma (liquid metals
with chunks of rocks)
Largest Layer
1,800 miles
solid rocks &
Liquid
Outer Core Nickel & Iron 1,400 miles Liquid
Inner Core Mostly Iron
(highest density)
760 miles Solid
The Crust
The Earth's Crust is
like the skin of an
apple.
Continental crusts are
thicker than oceanic
crusts
The Mantle
The Mantle is the largest
layer of the Earth.
The movement of the middle mantle (asthenosphere) is the reason that the crustal plates of the Earth move.
The Outer Core
The core of the Earth
is like a ball of very
hot metals. The
outer core is so
hot that the metals in
it are all in the liquid
state.
The Inner Core
The inner core of
the Earth has
temperatures and
pressures so great
that the metals are
squeezed together
and are not able to
move, so its solid.
Composed of iron
and nickel.
The Lithosphere
• Crust and upper mantle
• Rigid, brittle rock
• Moves together in plate tectonics
The Asthenosphere
• layer of middle mantle where
convection happens.
•Semi-rigid.
•Lithosphere Plates move due the
convection in the Asthenoshpere.
The Lithospheric Plates
The crust of the Earth is broken into many pieces called
plates. The plates "float" on the asthenosphere.
•Source of Earth’s interior heat started with the kinetic
energy of the collisions of metal, rock and ice fragments
converted into heat energy as the fragments impacted
with the growing Earth.
•As the Earth become compact, the gravitational energy
was converted into heat.
•The third source of heat is the decay of radioactive
elements that change to more stable forms, releasing heat
in the process. Radioactivity is one of the main sources of
heat inside the Earth.
Convection Currents
The middle mantle "flows"
because of convection
currents. Convection
currents are caused by the
very hot material at the
deepest part of the mantle
rising, then cooling and
sinking again --repeating
this cycle over and over.
Convection• Occurs because of difference of
temperatures of the materials.
• Occurs because heated material becomes
Less dense and rises
• While materials cooling down become more
dense and sink.
**** Will
See this again in
Oceans and
Atmosphere
Moho Boundary
• Separates the crust from the upper mantle.
Moho, or Mohorovičić
discontinuity, boundary
between the Earth’s crust
and its mantle. The Moho
lies at a depth of about 22
mi (35 km) below
continents and about 4.5 mi
(7 km) beneath the oceanic
crust. Modern instruments
have determined that the
velocity of seismic waves
increases rapidly at this
boundary. The Moho was
named for Andrija
Mohorovičić.
Seismic Waves• waves of energy that travel through
the Earth, and are a result of an
earthquake, explosion, or a volcano.
• We know about the layers of the
Earth because of theses waves.
2 types of waves:
1. P-wave - primary
wave, can travel
through liquids
and solids
2. S-wave - secondary
wave, Can only travel
through liquids
Main regions of Earth’s
interior:
1. Inner Core
2. Outer Core
3. Mantle
4. Crust
5. Magnetosphere
MAGNETOSPHERE
Region around Earth that
is influenced by Earth’s
magnetic field
- Rapid Rotation
- Metal (electrical conductor)
• magnetic field generation requires:
- Liquid Core
Will a compass lead you directly
to the geographic North Pole???
Magnetic Variation
A compass does not point directly to
the north pole but to the magnetic
north pole. This difference is called
magnetic variation.
Van Allen Belts
Two regions surrounding Earth
that capture high-energy
charged particles
**Particles originate in solar wind and
flares
a) outer belt - contains mostly
lighter electrons
b) inner belt contains
heavier protons
Charged particles then
collide with air molecules,
get excited, then…
Produce spectacular light show
called Auroras “Northern
Lights”
“Northern Lights”