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The Layers of the Earth
The Layers of the Earth
The Earth is composed of four different layers:
• The crust, mantle, outer core and inner core.
layers of earth
The Crust
• Earth’s thinnest layer
• Made up of silicon, oxygen and magnesium
The Crust
The crust is composed of two different rock types:
-Continental crust: thicker, less dense, older, made
of granite
-Oceanic crust: thinner, more dense, younger and
made of basalt
Tectonic Plates
• The crust is broken up into “plates” that move
around on top of the mantle
The Mantle
•
•
•
•
The thickest layer of the Earth.
Made up of silicon, magnesium and iron
Lithosphere: the crust and top of the mantle
Asthenosphere: below the lithosphere, the upper
mantle
–Made up of plastic-like rock that flows and
causes plates to move
• is the mantle liquid? (start at 3:24)
The Mantle
• Mesosphere: the lower part of the mantle
• Makes up most of the mantle and is molten rock
Earth’s Layers
• Sci Show Earth's not so juicy center
The Outer Core
• Made up of liquid nickel
and iron
• Convection currents in the
outer core create the
Earth’s magnetic field
The Inner Core
• Made of solid iron
• Remains in a solid state
because it is under extreme
pressure
Inner Core
• The Earth’s core is so hot because the:
• heat of formation and
• radioactive decay
Why is the core so hot?
Heat of Formation
• Heat of formation: the formation of earth created
intense heat.
• Some of that heat is still inside Earth’s core
• Accounts for 50% of earth’s internal heat
Radioactive Decay
• Radioactive Decay: as radioactive elements in
rocks decay they give off energy in the form of
heat (ex. uranium and thorium)
• Accounts for 50% of earth’s internal heat
Layer
Lithosphere
Asthenosphere
Mesosphere
Outer
Core
Inner Core
Thickness
5-60 miles
430 miles
1800 miles
1400 miles
760 miles
Made
out of
Rock: Granite
and Basalt
Rock:
Silicate
materials
Rock:
Silicate
materials
Metal:
iron and
nickel
Metal: Iron
State of
matter
Solid
Plastic-like
Molten
(liquid)
Molten
(liquid)
Solid
Unique
• Thinnest
layer
• 2 types
Lithospheric
plates move
on top of this
layer
Convection
currents
cause the
plates to
move
Creates
Earth’s
magnetic
field
Under the
highest
pressure
Properties
Kola Superdeep Borehole: Russia
• Deepest hole ever dug: scientific expedition
• 12,262 meters (7.6 miles)
• The temperature at this depth was 180°C (356°F), at which point the rock
became more like a plastic than a solid, stopping further drilling
• how deep have we drilled?
Argyle Diamond Mine: Australia
• Largest hand dug hole in the world
• Largest volume of diamonds produced
– 600 meters (1,970 ft)
Chuquicamata: Chile
Udachnaya: Russia
Mirny Diamond Mine: Russia
Bingham Canyon Mine: Utah
Sinkhole: Guatemala
Great Blue Hole: Belize
Darvaza:Turkmenistan
• The door to hell
How do we know all of this?
• Scientists use seismic waves to analyze Earth’s
layers
• Shadow zones: places on earth where no seismic
waves reach
• S-wave: a type of earthquake wave that cannot travel
through the liquid outer core
Mantle Convection
• Convection: the transfer of heat through the
movement of a fluid
• Hot magma rises and cooler magma sinks
• The rising and sinking magma creates a convection
current
• Convection currents cause tectonic plates to move