Download Layers of Earth Notes

“Window” to the
Earth’s Interior
1. Excerpts from
the Bryson
article
2. Respond to the
prompts
WARM UP…
Use the pieces you have from
your envelope to construct a
square. Work by yourself and
keep your eyes on your own
square!
NOW…
Use the pieces you have from your
envelope AND the extra piece I have
given you to construct a square.
Work by yourself and keep your eyes
on your own square!
Which looks
like Early
Earth during
it’s formation?
A
B
?How did Early Earth Form?
•Homogeneous collection of small solid
particles
• Heat Generated by “friction” causing the
interior to become
•Dense material moved to the center; less
dense to the edges
•Materials that hit the Earth caused it to grow
•As Earth began to COOL Radioactive elements moved
out and heat was released
Geologic history began when solid rock
formed.
over 3.8 billion years ago.
No rocks from that time exist today.
Why?
Earth’s layers Divided 2 different ways:
1. Based on composition
2. Based on physical properties
•Three layers based on composition
•Crust - Outermost layer - solid
•Mantle - Below crust -liquid
•Core - Center layer - solid/liquid
•Layers vary in types of rock, density,
temperature, state of matter, and thickness
1. Excerpts from
the Bryson
article
2. Respond to the
prompts
Densest layers are in the core
because denser objects always
sink due to gravity, while less
dense objects float to the
surface.
Continental Crust
Oceanic
Crust
Continental
crust
Often
composed
of granite
mostly Al,
Si, O, Ca,
Na, K
thick (32
km)
Oceanic
crust
Usually
composed
of basalt
mostly Si,
O, Fe, Mg
thin (8 km)
Why does oceanic crust sit lower than continental crust?
- Basalt is more dense than rocks in continental crust.
A. Between
the core and
crust
B. Most of the
Earth’s mass is
in the mantle
(thickness =
2900 km or
1800 miles)
C. Made of Si,
O, Fe & Mg Contains more
Mg, which is
denser than Al
in the crust
D.
Temperature =
870oC –
2200oC
(1600oF –
4000oF)
The top layers of the mantle are hot enough to be
plastic or semi-liquid, which allows it to… FLOW
(10,000 times slower than the hour hand on a clock!)
There are places in
the ocean where
the mantle
pushes through
to form new rock
along the ocean
floor.
As a result, the ocean
floor has a similar
composition to the
mantle.
Makes up
1/3 of the
Earth’s
mass
Made
mainly of
iron and
nickel (the
denser
elements)
Almost no
silicon,
oxygen,
and
aluminum
Outer Core
•Molten (liquid) Fe & Ni – produces Earth’s magnetic field
•Surrounds Inner Core
•Temperature = 2200-5000C
•Less pressure than inner core
Inner Core
•Solid Fe & Ni
•Temperature = 5000oC
•Extreme pressure
Why do you think part of the
core is liquid, when the
inner core is solid?
The intense pressure at the center of
the Earth squeezes it into a solid!
DISCOVERING EARTH’S
LAYERS
Oldham 1906
Mohorovičić 1909
Lehmann 1936
1. Observe the diagram of the Earth
2. Follow the directions and add the
layers with regards to physical and
structural composition
3. Label according to the directions
Five layers based
on physical
properties:
1) Lithosphere
2)Asthenosphere
3)Mesosphere
4)Outer core
5) Inner core
Lithosphere •
•
2 parts: rocky crust and rigid,
outermost mantle
Litho- = “rock”
Asthenosphere  •
•
Mesosphere •
•
Plastic (flowing) upper mantle
directly beneath the lithosphere
Astheno- = “weak”
Dense, hard lower layers of the
mantle
Meso- = “middle”
•
•
•
Pieces of the lithosphere that
move around, floating on top of
the denser asthenosphere
Each plate fits together with the
plates around it.
There are 10 or so major plates,
but around 50 or more total,
including all of the smaller ones.
The South American plate is a single plate
containing both continental and oceanic
crust. It is surrounded by several other
oceanic plates.
1) Both oceanic and continental plates
float on top of the asthenosphere, like ice
cubes floating in water, because of
their… Lower density
2) Just like ice cubes, the
plates can move
around and often
bump into each other.
3) Some of the plate sits
below the level of the
asthenosphere, just
like ice displacing
water.
The thicker continental
crust displaces more of
the asthenosphere than
does oceanic crust.
During earthquakes,
seismic waves
(vibrations) are sent in
all directions, through
the earth.
They reach different places
at different times
because of the ways
the waves…
BEND and CHANGE SPEED
as they pass through
the internal layers.
1. How are the five layers divided?
2. Name the five layers and describe a
characteristic of each.
3. How do we know the physical state of
the layers if we have never traveled to
them?
Crust
Upper Mantle
Lower Mantle
Inner Core
Outer Core
1. How are the 3 layers divided?
2. Where are less dense materials located?
3. Do the layers follow the laws of density?
Do before you leave:
Write a mnemonic device or a sentence to
remember the composition of each layer?