Download Layers of the Earth

Layers of the Earth
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.
Continental Crust
Oceanic Crust
•
•
Thin & solid, outer
most layer
(5 – 100 km thick)
up to 870oC
(increasing with
depth)
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 (heavier) 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
Why the Earth is so hot
Five layers based on
physical properties:
1)
2)
3)
4)
5)
Lithosphere
Asthenosphere
Mesosphere
Outer core
Inner core
1
2
3
5
4
Lithosphere
litho = “rock”
• 2 parts: rocky crust and rigid,
outermost mantle
• TECTONIC PLATES!!!!
Asthenosphere
astheno = “weak”
• Plastic (flowing) upper mantle
directly beneath the lithosphere –
Due to heat and pressure
Mesosphere
meso = “middle”
• Strong, dense lower layer of the
mantle
Outer Core
Surrounds Inner Core
•
molten Fe & Ni – produces
Earth’s magnetic field
•
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!
•
•
•
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 The thicker continental crust displaces
ice displacing water.
more of the asthenosphere than does
oceanic crust.
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 the internal
layers.