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Layers of the Earth
Notes
Earth’s Layers
• Earth is divided into layers
– 2 different ways
• Composition
– What it’s made of
• Physical properties
– What can be observed/doesn’t change chemical
properties
Earth’s Layers by Composition
• Crust
• Core
• Mantle
Core
Earth’s Layers by Composition
• Crust
– Outermost layer
– Thinnest layer
– Composed mostly of oxygen,
silicon, and aluminum
– Two types
• Oceanic (found under oceans;
more dense)
– Twice as much iron, calcium, and
magnesium which are more dense
minerals
• Continental (found under land;
less dense)
Earth’s Layers by Composition
• Mantle
– Between the crust and
core
– Much thicker than crust
– Composed of more
magnesium and less
aluminum and silicon
than the crust so it is
more dense than the crust
Earth’s Layers by Composition
• Core
– Below the mantle; at the
center of Earth
– Makes up 1/3 of Earth’s mass
– Composed primarily of iron
and nickel
• Almost no oxygen, silicon,
aluminum, or magnesium
– Heats the mantle by
convection
Earth’s Layers by Physical
Properties
•
•
•
•
•
Lithosphere
Asthenosphere
Mesosphere
Outer Core
Inner Core
Earth’s Layers by Physical
Properties
• Lithosphere
– Solid, outermost part
of Earth
• Includes crust and rigid
upper part of mantle
– Divided into pieces
called tectonic (or
lithospheric) plates
Earth’s Layers by Physical
Properties
• Asthenosphere
– Found directly under the
lithosphere
– Tectonic (lithospheric)
plates move on this layer
– Made of solid rock that
flows slowly
Earth’s Layers by Physical
Properties
• Mesosphere
– Found directly under the
asthenosphere
– Lowest part of the
mantle
– Very strong
Earth’s Layers by Physical
Properties
• Outer Core
– Found beneath the
mesosphere
– Liquid layer of Earth’s
core
– Surrounds inner core
– Made of iron and nickel
– Heats the mantle by
convection
Earth’s Layers by Physical
Properties
• Inner Core
– Found beneath the outer
core
– Solid layer of Earth’s
core
• Very dense
– Made of iron and nickel
Earth’s Magnetic Properties
• Earth acts like a giant magnet
• Earth (like any manufactured
magnet) exhibits 2 poles
– North
– South
• Earth’s outer core spins as Earth
rotates
– This creates the magnetic field
Compass
• A compass is composed of a small, lightweight magnet (called a needle)
– Balances on a point
• One pole of the magnet will be
attracted and point toward the Earth’s
North Pole
– This pole on the magnet is called the north
pole of the magnet
• Compasses are used for navigation from
any point on Earth’s surface
– Possible because of Earth’s magnetic field
Layers of Earth Comparisons
PHYSICAL
PROPERTIES
Lithosphere
Asthenosphere
Mesosphere
Outer Core
Inner Core
COMPOSITION
Crust
Mantle
Core
Layers of Earth Comparisons
Lithosphere
Asthenosphere
PHYSICAL
PROPERTIES
Crust
COMPOSITION
Mantle
Mesosphere
Core
Outer Core
Inner Core
Layers of Earth Comparisons