Download Chapter 1 Introducing Earth

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What is inside the Earth?
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In nature there are many examples of things
that work together.
◦ Organisms depend on the environment for food,
water, shelter, and space.
◦ The Earth itself both its living and nonliving parts
make up what is known as a system.
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System
◦ A group of parts that work together as a whole.
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The Earth involves a constant flow of matter
through different parts.
◦ Such as the water cycle or carbon/oxygen cycle.
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Rock also goes through cycles.
◦ Magma gathers beneath the Earth and when it
reaches the surface as lava hardens into rock.
◦ Over time this may erode into smaller pieces.
◦ The sediments may later on be compressed and
become a whole new rock.
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How do systems work?
◦ All systems require Energy.
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Energy
◦ The ability to do work.
◦ Work can be thought of as anything physical or
involving change.
◦ The Earth has two main sources of energy that drive
it.
 Heat from the sun, and heat flowing out of the Earth as
it cools.
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The Earth System contains land, air, water,
and life all of which make up their own
“sphere”.
◦ All of these spheres receive energy from the sun.
◦ One of the most important parts of the system is
humans.
◦ Humans greatly effect air, water, land, and life.
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Atmosphere
◦ The relatively thin envelope of gases that forms
Earth’s outermost layer.
◦ Contains all the gases we and other living things
breathe, as well as all facets of the weather.
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Geosphere
◦ The rocks, metals, and minerals that make up the
Earth.
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Hydrosphere
◦ Contains all of Earth’s water.
◦ This includes all freshwater and saltwater sources.
◦ As well as all ice and water vapor.
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Biosphere
◦ The parts of Earth that contain living things.
◦ This can overlap a bit with the other spheres.
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Feedback in a System
◦ Changes in one part of the Earth or in one sphere
may effect others.
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Pg. 6-7
◦ Figure 2
◦ Assess Your Understanding

What are the different spheres which the
Earth is divided into?
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The land is constantly being created and
destroyed by competing forces.
◦ Recall that the Earth’s plates are moving in the
process called plate tectonics.
◦ This is forcing some rock to push upwards.
◦ At the same time erosion is always wearing down
the features of the Earth.
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Constructive Forces
◦ Forces that construct or build up mountains.
◦ Volcanoes build up Earth’s surface by spewing lava,
which hardens into new layers of rock.
◦ Earthquakes can cause mountains to rise.
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Destructive Forces
◦ Forces which wear down, or destroy land masses.
◦ Ice, rain, wind, and changing temperatures all work
to wear down all land features.
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Pg. 9
◦ Assess Your Understanding

What’s the difference between a constructive
and destructive force?

Processes effecting Earth’s surface are often
the result of things going on in the interior.
◦ Geologists aren’t able to go deep within the Earth
yet, but they have begun to answer questions about
what’s inside.
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Evidence from Rock Samples
◦ Geologists have drilled holes as deep as 12.3 km
(7.6 miles) into the Earth.
◦ The rocks they have brought back show the make
up and the structure of the Earth beneath the
surface.
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Evidence from Rock Samples (cont.)
◦ Volcanoes and lava also provide some samples from
100 km or deeper (62 miles)!
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Evidence from Seismic Waves
◦ Earthquakes produce seismic waves.
◦ Geologists use seismographs to record these waves
and how they travel through the Earth.
◦ The waves’ speed and path helps scientists to
determine what the Earth is made of.
 This has shown us that there is more than rock down
there.
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There are three main layers to the Earth:
◦ The Crust
◦ The Mantle
◦ The Core
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The deeper in the Earth we go the greater the
pressure gets.
◦ Pressure is caused by a force pressing on an area.
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The deeper in the Earth we go the greater the
temperature gets.
◦ This is caused, much like pressure, by the mass of
rock above.
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The Crust
◦ The layer of rock that forms the Earth’s outer skin.
◦ It includes both dry land and the ocean floor.
◦ The crust is a relatively thin layer, only reaching a
thickness of 40 km at its thickest (25 miles).
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Continental Crust
◦ The crust that makes up the continents and land,
it’s composition varies greatly.
◦ Much of it is made of granite, a rock that is light in
color and coarse in texture.
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Oceanic Crust
◦ The crust that makes up the ocean floor, it’s
composition is fairly constant.
◦ Much of it is made of basalt, a rock that is dark in
color and fine in texture.
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Pg. 12
◦ Figure 2
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Pg. 13
◦ The Earth’s Crust
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What is the topmost layer of the Earth called?
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The Mantle
◦ A layer of hot rock about 40 kilometers below the
surface which contains a lot of iron and
magnesium.
◦ Rock here is still solid, but it is very hot.
◦ There are three layers to the mantle:
 Lithosphere
 Asthenosphere
 Mesosphere
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The Lithosphere
◦ The uppermost part of the mantle.
◦ Like the crust this layer is made of strong, hard,
and rigid rock.
◦ It averages about 100 km (62 miles) thick.
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The Asthenosphere
◦ The second layer of the mantle.
◦ This layer is softer than the lithosphere, but still
solid.
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The Mesosphere
◦ The deepest layer of the mantle.
◦ This layer is hotter and more rigid because of the
intense pressure.

The Core
◦ The layer below the mantle is Earth’s core.
◦ The core is made up of mostly the metals iron and
nickel.
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Outer Core
◦ A layer of molten metal surrounding the inner core.
◦ This layer is entirely liquid.
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Inner Core
◦ A dense ball of solid metal at the very center of the
Earth.
◦ This layer is harder and packed more tightly than
any other layer of the Earth.
◦ This is caused by the extreme pressure on the core.

The Earth has a magnetic field that which
causes it to act like a giant magnet.
◦ Scientists believe that the liquid outer core is
responsible for creating this.
◦ If metal objects were to surround the Earth they
would be pulled in much in the same way that a
magnet pulls metal to it.
 The Earth is after all a very large magnet.
 This is also why a compass always points north. It is
drawn to Earth’s north pole.
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Pg. 16-17
◦ Earth’s Interior.
◦ Assess Your Understanding.

How is the inner core different from the outer
core?
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
Heat is constantly being transferred inside
the Earth and all around its surface.
Heat always moves from a warmer object to a
cooler object.
◦ As an object is heated the particles that made up
the object move faster.
◦ The faster the particles move, the more energy they
have.
◦ This process is called heat transfer.
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Radiation
◦ The transfer of energy that is carried in rays of
light.
◦ This is done constantly by the Sun.
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Conduction
◦ Heat transfer between materials that are touching.
◦ Such as between food and most ovens.
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Convention
◦ Heat transferred by the movement of a fluid.
◦ Warm air causes balloons and birds to be able to
fly.
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Density
◦ The measure of how much mass there is in a given
volume of some substance.
◦ Mass is the amount of matter in an object.
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A constant flow occurs in which substance at
the bottom heats up and rises as cooler
substance is pulled down to be heated and
then it cycles again.
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Convection Current
◦ The flow that transfers heat within a fluid.
◦ If heat was not present the current would eventually
stop.
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Heat from the core and mantle cause
convection currents in the mantle.
◦ The solid rock that is the mantle melts a bit and can
move much like gum or putty that stretches but
does not break.
◦ Over time the layers fold over one another causing
the current to cycle.
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Pg. 19
◦ Figure 1
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Pg. 21
◦ Assess Your Understanding