Transcript Inside the Earth

Inside the Earth
Evidence
• Geologists can’t observe Earth’s interior directly.
• Must observe indirectly through seismic waves.
• Caused by earthquakes,
seismic waves are
vibrations of matter (kinetic
energy) that travel through
the various mediums of
earth at different rates.
• By measuring recording
seismic waves at multiple
locations on earth, scientist
have been able to infer the
density and composition of
earth’s interior.
Composition
• Crust
• Mantle
• Liquid Outer Core
• Solid Inner Core
The Crust
• Outer layer
• 5-40 km thick
• It is thinnest beneath the
ocean and is thickest below a
mountain.
• 2 types of crust
– Oceanic (very dense,
made of basalt)
– Continental (less dense,
made of granite)
Basalt
Granite
The Mantle
• About 3,000 km thick
• Mantle is soft rock and flows
freely like melted plastic.
• Temperature and Pressure
increase with depth.
• Temperatures range from
870°C to 2,200°C
• Convection currents
Convection video:
http://education.sdsc.edu/optiputer/flash/convection.htm
Liquid Outer Core
• Consists of liquid iron
and Nickel.
• Currents in the liquid spin
to generate the earth’s
magnetic field.
• Can be as hot as 5,000°C
Earth’s Magnetic Field
Solid Inner Core
• An extremely dense ball of solid metal.
• The inner cores and out cores together are just slightly
smaller than the Moon
• So much pressure that the liquid
iron and nickel can not spread
out to form a liquid.
Scientist think the spinning of the inner core is what causes
the currents in the outer core, and thus, Earth’s magnetic
field.
Earth’s Layers
• How are the earth’s
layers similar to an
egg?
• Shell=crust
• Egg white=mantle
• Yolk=core
Upper Layers of the Earth
• Lithosphere - rigid outer layer - including the crust and
uppermost mantle.
• Asthenosphere – rock material that flows slowly
(Ductile - like hot asphalt) - including the lower mantle
Tectonic Plates
• Earth’s crust is broken into about 19 pieces
• These plates move on top of the asthenosphere
• Throw yo hands up for the layers of the
Earth !!!
Earth’s Layers Video