Transcript Earths Layers

Earth’s
Layers
WARM-UP
Exploring Earth’s Interior (Article)
1. How did the author use the following as analogies in
the reading? Pick TWO and briefly explain (use the
article for help if you do not remember)
Ford cars & World Series
Brick traveling 45 minutes
An apple’s skin
Sidewalk in New York city & strand of spaghetti
2. How do we know the different layers exist?
Exploring Earth’s Interior (Article)
What were the THREE main points of this part of the
reading.
Earth’s Layers (Article)
Provide at least TWO facts about each layer of the
Earth.
What is the lithosphere & asthenosphere?
WARM-UP
1. How do you think pressure and
temperature change as you move
closer to the center of the Earth?
Why?
Earth’s layers  Divided 2 different ways:
1. Composition (What it’s made of)
2. Physical Structure (Ex: solid or liquid)
Three layers based
on composition:
1) Crust
2) Mantle
3) Core
Note: Denser material collects
in the core because denser
objects always sink due to
gravity.
A. Makes up 33% of the
Earth’s mass
B. Mostly Fe with some
Ni (the denser
elements)
C. Little to No: O, Si, Al
& Mg
A. Between the core and
crust
B. Contains most of the
Earth’s mass (67%)
C. Mostly Mg & Fe with some
Si, O, & Al (more Mg
than Al, because Mg is
more dense)
D. Temperature = 870oC –
2200oC
E. Composition studied from
volcanic eruptions
•
•
Continental
Crust
Oceanic Crust
Continental Crust
Oceanic crust 
Thin & solid, outer most layer
(5 – 100 km thick)
up to 870oC (increasing with
depth)
Often composed of granite; mostly Si, O, Al,
Ca, Na, K; thick & less dense
Usually composed of basalt; mostly Si, O, Fe, Mg;
thin & more dense
Why does oceanic crust sit lower than continental crust?
- Basalt is more dense than rocks in continental crust.
Five layers based on
physical properties:
1) Lithosphere
2) Asthenosphere
3) Mesosphere
4) Outer core
5) Inner core
1
2
3
5
4
Lithosphere
• 2 parts: rocky crust and rigid,
outermost mantle
• TECTONIC PLATES!!!!
Asthenosphere
• Plastic (flowing) upper
mantle directly beneath the
lithosphere – Due to heat and
pressure
Mesosphere
•
Strong, dense lower layer of
the mantle
Outer Core
•
molten 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 the outer core is
liquid, when the inner core is solid?
The intense pressure at the center of the
Earth squeezes it into a solid!
When earthquakes occur,
seismic waves
(vibrations) are sent out
in all directions, through
the earth.
These vibrations reach
different places at
different times because
of the ways the waves…
BEND and CHANGE SPEED
as they pass through
Earth’s layers.
Journey to the Center of the Earth (Discover June 2007)
The deepest exploration ever: The Kola bore hole (about twice the size of a softball) the
Russians drilled in the 70s and 80s reached a depth of 7.6 miles into the continental crust of
Russia.
They hit temps of 356 degrees F.
But only reached a mere 0.2% of the way to the core.
Most scientists agree the Earth’s core is sold iron and nickel, but some disagree
Some think it could be like a nuclear reactor or even a massive crystal at the center.
The question is will we ever reach the center to find out?
One problem is trying to recreate the conditions of the Earth’s interior (pressure & heat) to test
ways to explore its depths
One geophysicist has an interesting idea –
Open a crack in Earth’s crust with a controlled blast
Then pour in 100,000 tons of liquid iron along with several refrigerator size probes
Gravity should pull the liquid iron and probes down to the core in about one weeks time
The path behind the iron would naturally seal its self up.
The probes would communicate with the surface by seismic waves, sending up info about the cores.
Why not do it? $$$$$