Download Chapter 2 Earth`s Interior

CHAPTER 2
EARTH’S INTERIOR
Sylvia Marquez
VOCABULARY
• Seismic waves-waves formed
during an earthquake
• Granite-a rock usually is a light
color and has coarse grains
• Outer core-is a layer of molten
metal surrounding the inner core
• Pressure-force pressing on an
area
P=F =force
A=area
•Mantle-layer of solid rock, it is
under the crust
• Inner core-is a dense ball of solid
metal
• Crust-the layer of rock that forms
Earth’s outer skin
• Lithosphere-the crust and
uppermost mantle
• Basalt-a dark, fine-grained rock
• Asthenosphere-part of the
mantle just beneath the
lithosphere, less rigid than the
rock above. Over thousands of
years this part of the mantle can
bend like a metal spoon
HOW DO GEOLOGISTS LEARN ABOUT
EARTH’S INTERIOR?
• Processes that affect Earth’s surface are often
a result of what’s going on inside Earth. But
what’s inside Earth? Geologists use two main
types of evidence to learn about Earth’s
interior: direct evidence from rock samples
and indirect evidence from seismic waves.
EVIDENCE FROM ROCK SAMPLES
• Geologists have drilled holes as deep as 12.3
kilometers into Earth. The drills bring up samples
of rock that give them clues about Earth’s
structure and conditions deep inside Earth,
where the rocks formed. In addition, volcanoes
sometimes blast rock to the surface from depths
of more than 100 km. These rocks provide
information about Earth’s interior.
• Also, in laboratories, geologists have recreated conditions inside Earth to see
how rock behaves. They use laser beams
on pieces of rock while squeezing the
rock with great force, to find out how
elastic rocks are. They do this to show
how rocks behave under great pressure.
EVIDENCE FROM SEISMIC WAVES
• Geologists also use an indirect method. When
earthquakes occur, they produce seismic waves.
Geologists record the waves and study how they
travel through Earth. The speed of seismic waves
and the paths they take give geologists clues about
the structure of the planet. The paths of these
waves reveal areas inside Earth where the makeup
or form of material changes. To better understand
how this works, let’s see a video.
Let’s watch this video to learn
more about seismic waves
HTTPS://WWW.YOUTUBE.COM/WATCH?V=AY6SG7GPALO
ASSESS
• Other than rock. What do you think you can find below the
surface of Earth?
• How did geologists gather information from the interior of our
planet?
• What direct evidence of Earth’s interior do geologists use?
• What limitation do geologists have when studying Earth’s
interior?
• How did the behavior of the waves “show” the location of
different layers on Earth’s interior?
FEATURES OF EARTH’S CRUST,
MANTLE, AND CORE
• The layers that make up Earth vary in thickness,
composition (the elements that make them up), and
pressure (the amount of force pressing on them).
• Scientists know that Earth’s interior is made up by
three main layers, and each one covers the layers
beneath it, like the layers of an onion.
The three main layers are:
 Crust-a layer of solid rock
that includes both dry land
and the ocean floor
 Mantle-is made out of rock
that is very hot, but solid.
 Core- made mostly of the
metals iron and nickel, but it
also has oxygen, sulfur, and
silicon
• Each layer has its own characteristics, some of
them apply throughout all of Earth. For example,
the deeper inside Earth, the greater the mass of
the rock that is pressing down from above.
• Pressure results from a force pressing on an area
because of the weight of the rock above,
pressure inside Earth increases its depth. The
deeper down inside Earth, the greater the
pressure.
• The mass of rock that presses down from above
affects the temperature inside Earth. The
temperature inside earth increases as depth
increases.
• Beneath Earth’s surface, the surrounding rock is
cool, but a 20 meters down, the rock starts to get
warmer.
• For every 40 meters of depth from that point, the
temperature typically rises 1 Celsius degree
CRUST
• The layer of soil where you step on is called crust
• The crust is a layer of solid rock that includes both dry
land and the ocean floor
• The main elements in the crust are oxygen and silicon
• It’s thinner than the layer that lies beneath it
• In most places, the crust is between 5 and 40 km, thick
• It is thickest under high mountains-where it can be as
thick as 80 km.-and thinnest beneath the ocean
• The crust beneath the ocean is called oceanic crust
• Its overall composition is much like basalt, with small
amounts of ocean sediment on top
• The crust that forms continents is called continental
crust, it contains many types of rocks
• Unlike oceanic crust, its composition varies greatly, but
it is mostly formed by granite
• What percent of the crust is iron?
• Which element makes up 2.6 percent of the crust?
• In total, how much of Earth’s crust is made up of oxygen
and silicon?
• What is temperature?
• What general statement can you make about the
change in temperature through Earth’s interior?
• What general statement can you make about the
change in pressure inside Earth?
• Why does temperature increase the deeper you go?
• Which type of crust is thicker?
• Is it possible for solid rock to flow?
ASSESS: CREATE A TABLE COMPARING THE TWO
TYPES OF CRUST BY FILLING THE INFORMATION
REQUIRED
Oceanic Crust
• Typical rock:_________
• Relative grain size:_________
• Color:_________
• Thickness:_________
• Forms:________
Continental Crust
• Typical rock:__________
• Relative grain size:__________
• Color:________
• Thickness:__________
• Forms:_________
MANTLE
About 40 km. beneath dry land, the rock in
Earth’s interior changes. The rock contains
more magnesium and iron than rock above it.
The rock below the boundary is the solid
material of the mantle, a layer of hot rock. The
mantle is made of rock that is very hot, but it’s
still solid. Scientists divide the mantle into layers
based on the physical characteristics of each
layer. Overall, the mantle is nearly 3,000 km.
thick.
LAYERS OF THE MANTLE
Lithosphere
Asthenosphere
Mesosphere
*Below the crust
*Below the lithosphere
*Beneath the
asthenosphere
*Brittle rock, like the
crust
*Uppermost layer
*Strong, hard, rigid
*Averages about 100
km. thick
*Hotter and under
increasing pressure
*Less rigid than rocks above
*Over thousands of years this
part can bend like a metal
spoon
*If you kicked it, it will stub
your toe
*Softer than the lithosphere
*It’s hot but more rigid
because of high
pressure
*It includes a region called
the transition zone, which
lies beneath the
asthenosphere
*It includes the lower
mantle, which extends
down to Earth’s core
MANTLE
CORE
Below the mantle lies Earth’s
core. It is made mostly of the
metals iron and nickel. It
consists of two parts-a liquid
outer core and a solid inner
core. The outer core is 2,258
km. thick. The inner core is a
solid ball. Its radius is 1,222 km.
The total radius of the core is
3,480 km. The core occupies
the center of the planet.
Outer Core
• A layer of molten metal
surrounding the inner core
• Despite enormous pressure,
it’s liquid
• It’s made of iron and nickel,
but it also contains oxygen,
sulfur, and silicon
Inner Core
• A dense ball of solid metal
• Extreme pressure squeezes
the atoms of iron and nickel
so much that they cannot
spread out to become liquid
• It’s made of iron and nickel,
but it also contains oxygen,
sulfur, and silicon
THE CORE AND EARTH’S MAGNETIC FIELD
• Scientists think that movement s in the liquid
outer core create Earth’s magnetic field.
• Because Earth’s magnetic field, the planet
acts like a giant bar magnet .
• Earth’s magnetic field affects the whole planet
EARTH’S MAGNETIC FIELD
• If you place a magnet on a piece of paper and sprinkle iron
filings on the paper, the iron filings will line up with the bar’s
magnetic field
• If you could surround Earth with iron filings, they would form a
similar pattern
• Let’s see: https://www.youtube.com/watch?v=j8XNHlV6Qxg
• When you use a compass, the compass
needle aligns with the lines force in Earth’s
magnetic field
• These lines meet at Earth’s magnetic
poles
• The needle points to Earth’s magnetic
north pole which is not the same location
as Earth’s geographic North Pole
MORE ABOUT MAGNETISM
• https://youtu.be/MQUH5ZXZNak
VIDEO: LAYERS OF THE EARTH
• https://www.youtube.com/watch?v=N9ncfAsmiSg
QUESTIONS
• Why is the asthenosphere different from the
lithosphere?
• How does the inner core differ from the outer core?
• Why do you think geologists consider the inner core
and the outer core as part of the same layer?
• How does the thickness of continental crust and
oceanic crust compare?
• Which of earth’s layer is the thickest?
• Which is the thinnest?
VENN DIAGRAM
Inner Core
Both
Outer Core
SUMMARIZE
Thickness/Radius
Composition
Solid/Liquid
Crust
5-80 km.
Granite/basalt
solid
Mantle
2,811-2,886 km.
Hot rock
solid
Outer Core
2,258 km.
Iron/nickel
liquid
Inner Core
1,222 km.
Iron/nickel
solid
TOTAL
6,371 km.