Transcript The Geosphere

Our Dynamic Earth
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Our Earth is made
up of rock, air,
water and living
organisms.
Rock = Geosphere
Air = Atmosphere
Water = Hydrosphere
Living organisms =
Biosphere
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Earth is composed of rock – both solid and
molten – as well as various metallic
elements.
This solid part of the Earth, as well as the
soil and loose rock on the exterior, makes
up the geosphere.
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The Earth’s geosphere is divided into three
chemical sections:
The crust, composed almost entirely of light
elements, like silicon.
The mantle, which is 68% of the Earth’s
mass.
The core, the innermost layer; it is
composed of very dense elements, such as
nickel and iron.
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The crust makes up
less than 1% of the
Earth’s mass.
There are two types
of crust:
◦ Continental crust,
and oceanic crust.
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Continental crust is
about 30-35 km
thick.
It is also made up
of lightweight and
low density
materials.
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Oceanic crust is
much thinner – it’s
only about 5 km
thick!
It is also made up
of heavier and
denser materials.
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The mantle is about 2900 km thick.
It is made up of dense materials, which are
rich in iron.
The mantle is semifluid; the molten rock
flows very slowly, which lets the solid plates
move on top.
◦ Much like cereal flows on top of syrup!
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The outer core is
composed of dense
liquid metallic
elements.
Mainly nickel and
iron.
Outer Core
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The inner core is
composed of solid
nickel and iron.
This is due to the
immense pressure
found at the center
of the Earth.
Inner Core
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The Earth’s solid elements (soil, earth and
rock) are collectively called the __________.
The geosphere has three chemical layers.
List them.
___________ crust is about 5 km thick, and
is made of relatively dense materials.
Why is the inner core solid?
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The Earth can also be divided into five
layers, based on its physical properties.
They are:
◦ Lithosphere – rigid and solid earth
◦ Asthenosphere – plastic; made of molten rock
◦ Mesosphere – Lower mantle, transitions to the
liquid outer core
◦ Outer Core – made of dense, molten iron and
nickel
◦ Inner Core – made of solid iron and nickel
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The lithosphere is
cool, solid and
rigid.
It is divided into
many smaller
pieces called
tectonic plates.
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The asthenosphere
is semi-fluid,
molten rock.
This allows the
tectonic plates to
move on top.
This motion is
essential to our
Earth‘s appearance.
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As discussed
earlier, our crust is
divided into smaller
tectonic plates.
These plates glide
on the surface of
the upper mantle.
The movement of
these plates can
have far-reaching
effects on us.
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A great deal of Earth’s tectonic activity
takes place at the boundaries of the
tectonic plates.
◦ Tectonic activity deals with activity that affects
Earth’s surface.
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Enormous forces are at work whenever the
tectonic plates collide, pull apart, or slip
beside each other.
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When the plates
collide with each
other, earth is
pressed upward
and folds.
This leads to the
creation of
mountain ranges.
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When plates slide past each other, faults –
breaks in the Earth’s crust – sometimes
appear.
The intense forces involved when this
happens cause earthquakes.
Most earthquakes are so minor that we
can’t feel them.
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The magnitude of an earthquake is the
energy that is released.
We use the Richter scale or the more
modern moment magnitude scale (MMS) to
measure this energy.
The lowest magnitude that can be detected
is about 2.0. The greatest magnitude that
has ever been recorded is 9.5.
Earthquakes that cause widespread damage
typically have a magnitude of 7.0 and up.
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Earthquakes can cause damage in various
ways:
◦ Pressure (P) and shear (S) waves cause vibrational
motion. P-waves cause up-and-down motion,
and S-waves cause side-to-side motion.
 S-waves are much more dangerous.
◦ Earthquakes can cause tsunamis, or large tidal
waves, if the originate in ocean areas.
◦ Earthquakes can liquify sandy areas, causing
buildings and other structures to sink into the
ground.
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What layer of the Earth contains the tectonic
plates? (2 possible answers)
Why can Earth’s tectonic plates move?
Most tectonic activity occurs along Earth’s
_____________________.
Mountain ranges are formed when tectonic
plates _________________.
Is it possible to never notice an earthquake?
Describe one way than an earthquake can
cause damage.
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Volcanoes are, in
essence, large vents
for molten rock to
rise to the surface.
We call this molten
rock magma while
it is underground,
and lava once it is
above ground.
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Volcanic vents often
form when plates
move apart from
each other.
This can happen on
the surface or
underwater.
Some vents appear
due to weak points
in the crust, called
hot spots.
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Volcanic eruptions
occur when magma
is trapped
underground, and
the pressure builds
up to critical levels.
Some volcanoes do
NOT erupt, as
magma is not
trapped, and can
flow freely.
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Volcanic eruptions can have devastating
effects on the Earth’s surface.
◦ Ash, dust and rock can bury building, crops and
organisms.
◦ Ash can mix with water to form dangerous
mudflows.
◦ Ash and dust can disrupt engines and breathing.
◦ Ash and sulfurous gases can reach the upper
atmosphere. Here, they block sunlight, which
reduces the average global surface temperature.
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Weathering is the process of breaking rock
down into smaller pieces.
Erosion is the process of moving the broken
rock and loose dirt elsewhere.
There are many forces that cause
weathering and erosion:
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Wind
Water and mudflows
Plant life
Human activity
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Volcanoes are primarily ___________________.
What are hot spots?
Why do some volcanoes NOT erupt?
Describe one way that a volcano can cause
damage.
List one means of weathering and erosion
on Earth.