Transcript Earth_s_Interior___Convection_2010

Tuesday January 5th, 2010
Set Up Your Cornell Notes
What is Earth’s Interior Like?
How do we know? (Evidence)
Show What You Know
• Draw a model/picture of what you
think the earth’s interior looks like
• What is the earths interior
composed of? Why? (explain your
answer)
Earth’s Interior
Sharing ideas
Layers of the Earth Diagram

Color code each layer
 Brown-Crust
 Orange-Mantle
 Yellow-Outer
Core
 Red-Inner Core

Label the Upper and Lower Mantle
 Dotted
line halfway between
Earth’s Interior
•
Earth Has 4 layers based on physical
properties
–
–
Crust
Upper Mantle
•
•
–
–
–
Lithosphere
Asthenosphere
Lower Mantle
Outer Core
Inner Core
How do we know what is down there?
• Direct Evidence
– Volcanoes sending lava out from below
– Rock Samples (deepest we have ever drilled is
just a few miles)
• Indirect Evidence
– Measuring Seismic Waves from Earthquakes
QuickTime™ and a
decompressor
are needed to see this picture.
QuickTime™ and a
decompressor
are needed to see this picture.
The Crust
• Two types of crust
– 5-40 km (3-24 mi) thick
– 1. Oceanic Crust
– Thinner
– Basaltic (dense & dark)
– 2. Continental Crust
– Thicker
– Granitic (lighter and
less dense)
The Mantle
• Layer under the crust (Upper and Lower Mantle)
– Upper part of upper mantle: is rocky and attached to the
bottom of the crust. (The Lithosphere)
– Lower part of upper mantle: soft and moves like warm
plastic. (The Asthenosphere)
The Upper Mantle
• Lithosphere
– The crust and the upper most part of the upper
mantle make up the lithosphere.
– The broken lithosphere makes up Earth’s
tectonic plates.
– Hard and rock like (lithos means stone)
– 100km (60 miles) thick
The Upper Mantle
• Asthensophere – Soft, plastic like rock
layer
– Can bend and flow
– Asthenes is Greek for
weak
The Outer Core and Inner Core
Outer Core:
–
–
–
–
–
LIQUID
SPINNING
Made of 90% Fe 10% Ni
Surrounds inner core
Creates Earth’s Magnetic Field
•
•
Ex: compass points North
Inner Core :
– Solid
– Also rotating
– Made of 90% Fe 10% Ni
Earth’s Magnetic Field
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Earth’s Magnetic Field
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Movement in the Mantle
What causes the movement?
• Convection – Heat transfer by the movement of fluids (air,
water, mantle material).
– Due to differences in temperature and density
– Creates a flow called a convection current.
– Heat from the core and the mantle causes the
convection current
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3 types of heat transfer
• Radiation - transfer by electromagnetic waves
• Conduction - transfer by touch
• Convection -
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A model of Convection
More Dense, Cooler
fluid - sinks
Less Dense, Hotter
fluid - rises
A model of Convection
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decompressor
are needed to see this picture.
A model of Convection
QuickTime™ and a
decompressor
are needed to see this picture.
A model of Convection
QuickTime™ and a
decompressor
are needed to see this picture.
A model of Convection
QuickTime™ and a
decompressor
are needed to see this picture.
A model of Convection
QuickTime™ and a
decompressor
are needed to see this picture.
Convection in the Mantle
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Movement in the Mantle
Forces involved
1.
Slab Pull
2.
Basal Drag
3.
Ridge Push
4.
Mantle Resistance
5.
Friction
• Convection: Transfer
of heat by the rising of
warm material and the
sinking of cooler
material