Download Earths Layered Structure

Earth’s Layered Structure
The story so far…… Evidence of Earth’s Layers and their composition
PHENOMENON:
What did you observe?
What evidence do you have?
OBJECTS:
Define the system.
What objects are interacting?
Rocks of Earth’s crust vary in density: granite is
less dense, then basalt, peridotite and iron
Density of Earth’s
Rocks Lab
Molten lava erupts from volcanoes.
Mohorovic found that EQ wave velocities
change at about 50 km.
Magma video clip
EQ P waves are reflected, bent, velocity
decreases and S-waves are stopped.
Earthquake P and
S waves
Earth has a north and south magnetic pole.
Compass,
Temperature, density and velocity changes at
certain depths: (100 km, 1000 km, 3000 km,
5000 km)
Ave. density of the crustal rocks ; granite, basalt,
peridotite is 3.0 g/cc. Yet the average density of
the entire Earth is 5.4 g/cc
Meteorites formed from the same materials at
the same time as the terrestrial planets. Some
of them are rocky and some are metallic
EQ waves were found to reflect, bounce off
“something” solid in the center
MOTION:
Describe the motion that in the model that explains your observations
EARTH’S CRUST is made of rocky material got
“sorted” by density when Earth was a young
molten planet. More dense iron sank to center
and less dense basalt and granite are on top.
Magma suggests that there is liquid, MANTLE of
molten rock under the solid, rocky crust
There is a boundary between the solid crust and
the liquid (magma) mantle layer.
magnets
Earth has an OUTER CORE composed of liquid
IRON that is flowing creates a magnetic field.
Rock Lab data
The Earth’s INNER CORE must be very dense
metal (iron 7.9 g/cc and nickel 8.9 g/cc) to
average out to 5.4 g/cc
Meteorite
samples
The inner core is SOLID iron and nickel
The Earth’s Interior (pg. 72)
Mantle:
Outer core:
Lithosphere
Continental Crust
Ocean Crust
Inner core:
Earth’s layer are
Determined by
these properties:
1.
2.
3.
Top Earth elements:
1.
2.
3.
4.
5.
Asthenosphere
So….Earth’s 4 layers were determined by
physical properties….
1. Temperatures and pressures
(both increase and change with greater depth)
2. Physical properties
(density, chemicals and elements)
3. Mechanical behavior
(how the material moves or doesn’t move: solid or liquid)
Earth’s Main Layers
•
•
•
•
Lithosphere/crust
Mantle
Outer Core
Inner Core
Outer core
Inner core
Crust / Lithosphere (pg. 72)
•
•
•
•
•
“litho-” stone, “-sphere” circle
Contains the crust and upper mantle
Relatively cool
Rigid, brittle, shell
Depth
– Ave. 100 km or 60 miles
Continental Crust
• Cold, brittle, fractures (earthquakes)
• Averages 35-40 km (25 miles ) thick
– Can exceed 70 km (40 mi) in mountains!
• Rock types:
– Upper crust is mostly light, silicate rocks such
as granite rock
– Up to 4 billion years old!
– 2.7 g/ml density
Oceanic Crust
• 7 km (5 miles ) THIN
• Composed of dark, igneous rock
– Basalt (black, ocean basin)
– 180 million years young
(or less)
3.0 g/ml density
•
•
•
•
upper mantle
100 km to 660 km
Soft, solid/liquid,
weak in structure,
constantly moving
Asthenosphere
(asthenos- weak)
Interaction between lithosphere and asthenosphere
• But the lithosphere sits “floats” on top of the
asthenosphere.
– Lithosphere (land) gets moved
(like a person being moved on an escalator)
Mantle
• The region that lies between the crust and
the outer core
• Thickest of the Earth’s layers
• Over 70% of Earth’s volume
• Down to 2900 km (1800 miles)
• Mostly solid, but…
– High temps. and pressure cause it
to behave in a plastic (putty) manner.
(like thick, hot asphalt)
Volcanic MAGMA comes from the
mantle
Outer Core
•
•
•
•
•
molten (liquid) IRON and nickel (alloy)
MOVES / FLOWS like a liquid
about 10% sulfur (S)
Density: 11 g/cm3
Convective flow of the liquid magnetic iron
causes the Earth’s magnetic field
Inner Core
•
•
•
•
Radius 1216 km (754 miles) size of our moon
Mostly IRON (Fe)
Spins?
Extremely high temperature (+3700°C or 6700°F)
• Yet it doesn’t melt, it’s Solid!
• Immense pressure of the overlying layers
prevent the iron from melting.
– Average density of 14 g/cm3
Earth’s Layers
Solid
Liquid
Pressure Temp.
(check)
(check)
Most-least
Crust
X
Mantle
X
Outer
Core
Inner
Core
X
Most-least
4
4
X
3
3
X
2
2
most
most
Earth’s Layers Review
Name that layer!
1.________: Solid iron and nickel most dense;
highest temperature due to intense pressure
2. ________: Liquid iron and nickel, flows to
produce Earth’s magnetic field
3._________: Most 70% (thickest layer)Compounds rich in iron, silicon, magnesium,
olivene, peridotite; molten magma originates here
4.________: Rigid layer of lighter rocks
5. ________________: Crust and uppermost mantle
6. ________________: Lithosphere floats on a thin,
slush-like layer of the mantle (UPPER MANTLE).
Lava lamp
Answers
Inner Core
1.________:
Solid iron and nickel most dense; highest
temperature due to intense pressure
Outer Core
2. ________:
Liquid iron and nickel, flows to produce
Earth’s magnetic field
Mantle
3._________:
Most 70% (thickest layer)-Compounds
rich in iron, silicon, magnesium, olivene, peridotite;
molten magma originates here
Crust
4.________:
Rigid layer of lighter rocks
Lithosphere
5. ________________:
Crust and uppermost mantle
Asthenosphere
6. ________________:
Lithosphere floats on a thin, slushlike layer of the mantle (UPPER MANTLE). Lava lamp