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Section 1-1
Earth’s Interior
S
Objectives
S F.1.1.1. Explain how Geologists
learn about Earth’s interior
structure.
S F.1.1.2. Identify characteristics of
Earth’s crust, mantle and core.
Exploring Inside Earth
S Geologists use two types of
evidence to study Earth’s interior:
direct evidence from rock samples
and indirect evidence from seismic
waves. Objective F.1.1.1.
Rock Samples-How Are These
Different?
What Are Some Things We Can
Learn From Rocks?
S Earth’s chemical composition.
S The interrelated processes that take place on Earth.
S Some structure and density.
S Volcanic eruptions, mountain building, weathering, erosion
and even earthquakes all involve rocks and minerals.
S Some minerals are quite valuable.
Sampling A Volcano
Evidence From Seismic Waves
S After an earthquake,
seismic waves travel
through Earth and
reveal information
about the internal
structure of the
planet.
Earth’s Layers
S The three
main layers of
Earth are the
crust, mantle
and the core.
Objective F.1.1.2.
Earth’s Layers
Pressure And Temperature
S As you descend deeper into the Earth,
what happens to pressure and
temperature?
S They both increase to thousands of
degrees and millions of tons of pressure.
Different Densities
S
Differences in density will cause
things to separate into layers.
S
Where does the “lighter” stuff
go?
S
It floats on top.
S
Where does the heavier stuff go?
S
It sinks to the bottom.
Earth’s Crust
S The crust is a layer of
solid rock that covers
the entire planet and
includes land and
ocean floor.
Objective F.1.1.3.
S Think of ocean floor
as land that is just
covered by water.
Earth’s Crust
S Earth’s crust is divided into two categories:
Oceanic and Continental.
S Oceanic Crust is made of Basalts that are dark
and fine texture.
S Continental Crust is made of Granite which is
often lighter in color and has a coarser texture.
Basalts/Oceanic Crust
Granite/Continental Crust
Where Else Have We Seen
Basaltic Lava Flows
Earth’s Mantle
S Earth’s mantle is made up of rock that
is very hot but still solid. Geologists
divide the mantle into layers based on
physical characteristics. Overall, the
mantle is around 1,800 miles thick.
Objective F.1.1.3.
Earth’s Mantle/Lithosphere
S The lithosphere is
the uppermost rigid
layer of the mantle
that includes the
top of the mantle
and the crust. It’s
about 60 miles
thick.
The Lithosphere
S Lithos is Greek for
Rock. So the
lithosphere is the
“rock” sphere of the
planet.
S It is made of the crust
and the uppermost,
solid part of the
mantle.
Earth’s Mantle/Asthenosphere
S The asthenosphere is
the next layer down.
It’s much hotter and
while it can slowly
flow and bend it is
still considered a
solid. Pressure keeps
it in solid form.
The Asthenosphere
S Just below the
lithosphere is the
asthenosphere. It is a
layer of solid rock that is
very hot, flows very
slowly and carries the
tectonic plates along
with it.
Earth’s Lower Mantle
S The lower mantle extends all the
way down to core.
S Do you know what causes the Earth
to “layer” itself ?
S Different Densities
Earth’s Core
S Earth’s core is made of the elements
iron, nickel and cobalt.
S Why did these elements sink to the center
of Earth?
S Because they are the most dense!
Earth’s Outer and Inner Core
How Are They The Same?
How Are They Different?
S Made of the
S The outer core
same metals:
Iron and Nickel.
is liquid.
S The inner core
is solid
Earth’s Core
S What squeezes the
inner core so much
that it becomes a
solid.
S Pressure from:
S Gravity
Earth’s Magnetic Field
S Geologists believe Earth’s
magnetic field is caused by
the movement of liquid in
Earth’s outer core.
S One thing we know for
certain is that the magnetic
field is essential for life on
Earth. It protects the planet
from the hostile environment
of space.
Earth’s Magnetic Field
Section 1-1 Assessment
S 1a. Why is it difficult to determine Earth’s inner structure?
S Because Earth is thousands of miles in diameter and we can
only drill a few miles deep into the crust. Therefore we must use
indirect methods to learn about Earth’s interior.
S 1b. How are seismic waves used to provide evidence about
Earth’s interior?
S Different types of seismic waves travel through different layers
of Earth at different speeds and when the waves are recorded
after an earthquake they carry information with them.
Section 1-1 Assessment
S 2a. List Earth’s three main layers.
S Crust-Mantle-Core
S 2b. What is the difference between the lithosphere and the
asthenosphere and where is each layer located?
S The lithosphere is the top layer and it is rigid. The
asthenosphere is below the lithosphere and it’s hotter and
under more pressure so it’s more plastic.
Section 1-1 Assessment
S 2c. Classify these layers.
S Lithosphere
S Solid
S Asthenoshpere
S Solid but can flow slowly
Section 1-1 Assessment
S Lower Mantle
S Solid but can flow slowly
S Outer Core
S Liquid
S Inner Core
S Solid