Earth’s Layers
6.E.2 Notes
Anatomy of Earth
• Crust
• Mantle
• Outer
Core
• Inner
Core
Crust
•Mostly
made up of rocks and
minerals covered by water,
sand, soil, and ice
•This layer is solid
•Thinnest layer; Makes up less
than 1% of the earth’s mass
Crust
•3-25
miles thick
•It is the least dense layer
•Temperature is the same
as the air because it
meets with our
atmosphere
Crust
•The crust consists of
continental plates and oceanic
plates
•When continental crust (6 to
47 miles thick) meets oceanic
crust (4 miles thick) it forms a
subduction zone (when two
plate tectonics collide)
Questions
• What
is the density of the crust?
• It
is the least dense layer of the earth, makes up less than 1% of
Earth’s mass
• What
does it mean when we say less dense or more dense?
• Density
is mass/ volume. When something is less dense it tends to
float, whereas more dense objects tend to sink
• How
thick is the crust?
• It
is the thinnest layer of the earth, 3-25 miles thick
• Is
the crust solid, liquid, or gas?
• Solid
• What
• Rocks
• What
• The
is the crust made of?
and minerals
is the crust’s temperature?
same temperature as the atmosphere
Lithosphere and
Asthenosphere
Lithosphere/ Asthenosphere
Lithosphere
• Is the crust and uppermost
part of the mantle
• Forms a rigid shell on the
outside of Earth.
• The rocks in the lithosphere
are strong and do not bend
easily
• It is broken into large pieces
called tectonic plates
Asthenosphere
• Is the partially melted
portion of the mantle below
the lithosphere
• It is hotter than the
lithosphere and can bend
more easily.
• The ability of the
asthenosphere to bend is
related to tectonic plate
movement.
Naming tectonic plates
• Tectonic plates are named • Tectonic plates are called:
based on its ability to
– Divergent: two plates move
away from each other
move in relation to
– Convergent: two plates move
another plate.
toward each other
• There are over 30 tectonic
– Transform: two plates slide
plates but scientist have
past each other.
identified 15 large plates.
• We live on the North
American plate which is
made up of:
– Oceanic Crust
– Continental Crust
Convergent Boundaries:
No subduction
Subduction Zone
When tectonic plates move
under another plate
• The plates become
crumpled and deformed.
• The plates do not crumple or
Due to neither plate
deform as they push towards
subducting, blocks of crust
each other. As the mantle near
slide upwards creating tall
the subducted plate melts,
mountains.
magma rises and forms a volcanic
arc on the plate that does not
subduct.
Convergent Subduction Zone
Oceanic and Continental Plates
•
When an
oceanic plate
encounters a
continental
plate, the
oceanic plate
plunges
beneath the
other plate.
Oceanic Plate Tectonics
Continental Tectonic Plates
No Subduction Zone
The effects of subduction zones
Mountain ranges can be
created by subduction
zones.
Subduction zones are at
high risk for earthquakes.
Transform Boundaries:
Creates Earthquakes
Divergent Boundaries:
Forms valleys
What causes tectonic plates to move?
• They move because of
convection, which
happens in the Earth’s
asthenosphere.
• Convection in the mantle
can drag plates over
Earth’s surface.
• The rocks in the mantle
are not hot enough to
bend easily but they can
flow in away similar to
fluids.
Mantle
• Layer
between crust and core
• Thickest
• 1800
layer of the earth
miles thick
• Made
up of dense, hot molten rock (mainly iron and
magnesium)
• Between
•A
convection current takes place in the mantle
• Causes
• It
1112-2192 degrees F
pieces of the crust to move
is mostly solid
Mantle
• The
mantle is split into upper
mantle and lower mantle
• The lithosphere is made up of
the upper mantle and the
crust
• The asthenosphere is below
the lithosphere
Mantle
• The lithosphere
contains ridged
rocks
• The
asthenosphere
contains rocks
that can flow
like a liquid
•
In the mantle we
have two layers of
solid rock with
heated flowing
rock between them
Let’s Review
• The Earth’s crust is divided into 12 major
tectonic plates
• These plates sit on the dense, hot, layer of the
earth known as the lithosphere
• Lithosphere = the crust and upper portion of
the mantle
• The Earth’s plates move about 2 inches per year
(5 centimeters)
• Convective currents within the mantle cause the
plates to move
• As they move, the plates:
– Press against one another (convergent
boundary)
– Pull apart from one another (divergent
boundary)
– Scrape against one another (transform
boundary)
Plate boundaries……
What is convection?
• http://www.youtube.com/watch?v=WEDUtS0I
Mws
Convection currents in the earth
• http://www.youtube.com/watch?v=jkKlGXG4lG
8
•
Alfred Wegener was a meteorologist that
believed that at one period of time the
continents were all connected.
•
People didn’t believe him because he
didn’t have enough evidence to support
his theory of the continents were moving
because people couldn’t feel it.
•
He believed over time the continents split
into separate pieces and shifted around
the world.
•
His theory was called the “Continental
Drift” .
•
He wasn’t the first to announce this
theory; however, he was the first to have
evidence:
•
Plants and animals
Continental
Drift
Pangea
Effects of Tectonic Plate Boundaries
• Major geological events occur at these
plate boundaries:
–Earthquakes
–Volcanic Eruptions
–Mountain Building
New mountain ranges are being formed where:
– two continental plates press against one
another
– An oceanic plate and a continental plate
press against one another
Thin oceanic plates spread outward at areas
known as mid-ocean rift zones.
Scientists who study how wave energy
travels through the different layers of
the Earth are called Seismologists.
Remember….
• Waves have characteristics such as:
• the number of waves that pass a given point in 1
second
• Frequency (speed of the wave)
• the height from the rest position to the bottom
of the trough or from the rest position to the
top of the crest
• Amplitude
• Distance from crest to crest or trough to trough
• Wavelength
Transverse waves…..
Earthquake: Seismic Waves
Write in notebook….
• During an earthquake, energy is released into
the Earth as:
• -Primary waves (compression waves)
• -Secondary waves (shear waves)
• -Surface waves
Write in notebook
•
Primary (P) waves travel
through both solid rock
(granite mountains) and
liquid regions (volcanic
magma or water of the
oceans) on the Earth
•
These waves are like
sound waves
(compression waves)
•
Travel the fastest
Write in notebook
•
Secondary (S) waves
only travel through
rock
•
Move twice as slow
as P waves
•
Moves at right angles
to the direction of
travel (transverse
waves)
Write in notebook
Surface wave
• Motion is felt along the ground and Earth’s
surface.
• Appear like waves or ripples of water that
travel across a lake
Types of earthquake waves
• Types Of Earthquake Waves
Questions
•
What are two parts of the mantle?
•
Upper mantle and lower mantle
•
What is the lithosphere?
•
Rocky outer parts of the planet. Makes up the upper mantle and the crust
•
How thick is the mantle?
•
It is the thickest layer of the earth, 1800 miles thick
•
Is the crust solid, liquid, or gas?
•
Mostly solid
•
What is the asthenosphere made of?
•
Rocks that can flow like a liquid
•
What is the crust’s temperature?
•
1112-2192 degrees F
Outer Core
• Made
up of liquid iron and nickel, or
molten metal
• 7232
degrees F
• 1400
miles thick
• Causes
• It
pieces of the crust to move
is liquid
• More
• Less
dense than crust and mantle
dense than inner core
Inner Core
• Made
up of solid iron and nickel
• Densest layer
• 9032 degrees F, just as hot as
the sun!
• It’s not liquid. The pressure
causes the iron and nickel to
solidify
Inner Core
• The
pressure comes from the
weight of the entire world
• Where
• This
the magnetic field lies
protects us from deadly
solar winds from the sun
Inner Core
Questions
•
Which part of the core is solid and which part is liquid?
•
Outer core is liquid, inner core is solid
•
What are the inner core and outer core made of?
•
Nickel and iron
•
What is the outer core’s temperature?
•
7232 degrees F
•
What is the inner core’s temperature?
•
9032 degrees F