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Chapter 3
Section 1 The Geosphere
The Earth as a System
• Earth is divided into four parts:
• The Geosphere
• The Atmosphere
• The Hydrosphere
• The Biosphere
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Chapter 3
Section 1 The Geosphere
Discovering Earth’s Interior
• Measure changes in the speed and direction of
seismic waves through different mediums.
• Earth is made up of different layers
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Chapter 3
Section 1 The Geosphere
The Structure of the Earth
• Compositional Layers
– Crust
– Mantle
– Core
• Physical Layers:
– Lithosphere - solid, outer layer of crust and upper
mantle (tectonic plates).
– Asthenosphere – “plastic” layer of mantle (flows
allowing tectonic plates to move).
– Mesosphere - lower mantle.
– outer core - liquid layer
– Inner core - center of the Earth, dense, solid, made
of iron and nickel.
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Chapter 3
Section 1 The Geosphere
Earth’s Layers
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Chapter 3
Section 1 The Geosphere
Plate Tectonics
• The continents are located on tectonic plates
• The major plates are
– Pacific
– North American
– South American
– African
– Eurasian
– Antarctic
• Tectonic plates may separate/collide/slip past one
another causing mountains, earthquakes, and
volcanoes.
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Chapter 3
Section 1 The Geosphere
Earthquakes
• Fault- break in the Earth’s crust
• When rocks under stress break along a fault,
earthquakes are set off.
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Chapter 3
Section 1 The Geosphere
Earthquakes
• Magnitude-energy released by an earthquake.
– smallest magnitude felt is 2.0
– largest magnitude recorded is 9.5
– Magnitudes >7.0 cause widespread damage.
• An increase of 1 whole number releases 31.7x more
energy.
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Chapter 3
Section 1 The Geosphere
Earthquake Hazard
• Scientists can determine where earthquakes are
likely to occur, not when.
• An area’s earthquake-hazard level is determined by
past/present seismic activity.
• Earthquake-resistant buildings are flexible so that
they can sway with the ground motion.
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Chapter 3
Section 1 The Geosphere
Volcanoes
• Volcanoes are often located near colliding/separating
tectonic plate boundaries.
• Most active volcanoes are on Pacific Plate
boundaries.
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Chapter 3
Section 1 The Geosphere
Local Effect of Volcanic Eruptions
• ash, dust, and gases can flow up to 200 km/hr and
sear everything in their path.
• volcanic ash can mix with water and produce
mudflows.
• ash can cause buildings to collapse, bury crops,
damage car engines, and cause breathing difficulties.
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Chapter 3
Section 1 The Geosphere
Global Effects of Volcanic Eruptions
• In large eruptions, clouds of ash and gases spread
across the planet reducing the amount of sunlight
that reaches the Earth’s surface.
• This can cause a drop in global temperature for
several years.
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Chapter 3
Section 1 The Geosphere
Erosion
• Erosion – Earth’s materials are transported from one
place to another by wind, water, ice or gravity.
• Erosion wears downs rocks and makes them
smoother over time. Older mountains are therefore
smoother than younger ones.
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Chapter 3
Section 2 The Atmosphere
The Atmosphere
• Gases can be added and removed from the
atmosphere through living organisms.
• Volcanic eruptions add gases to the atmosphere,
while vehicles both add and remove gases.
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Chapter 3
Section 2 The Atmosphere
Composition of the Atmosphere
• Nitrogen is 78% of the atmosphere (produced by
volcanoes and decaying organisms).
• Oxygen is 21% of the atmosphere (produced by
plants).
• Other gases include argon, carbon dioxide, methane,
and water vapor.
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Chapter 3
Section 2 The Atmosphere
Air Pressure
• Earth’s atmosphere is pulled toward Earth’s surface
by gravity, therefore, the atmosphere is denser near
the Earth’s surface.
• Air becomes less dense with elevation, so breathing
at higher elevations is more difficult.
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Chapter 3
Section 2 The Atmosphere
Layers of the Atmosphere
• Four layers based on temperature changes above
Earth’s surface.
• Troposphere
• Stratosphere
• Mesosphere
• Thermosphere
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Chapter 3
Section 2 The Atmosphere
The Troposphere
• troposphere
– lowest layer
– temperature decreases as
altitude increases.
– weather conditions occur
– densest layer
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Chapter 3
Section 2 The Atmosphere
The Stratosphere
• Stratosphere
– above the troposphere
– Temperature rises as altitude
increases because ozone in the
stratosphere absorbs the sun’s
UV energy and warms the air.
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Chapter 3
Section 2 The Atmosphere
The Mesosphere
• above the stratosphere
• coldest layer (temperatures as
low as –135ºF)
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Chapter 3
Section 2 The Atmosphere
The Thermosphere
• farthest from Earth’s surface
• nitrogen and oxygen absorb solar radiation resulting in
temps above 3,632 ºF
• air is so thin that air particles rarely collide, so little heat is
transferred, and would therefore not feel hot.
• X rays and gamma rays absorbed by nitrogen and
oxygen cause atoms to become electrically charged ions.
– lower thermosphere is called the ionosphere.
– Ions can radiate energy as light, which glow as the
Aurora Borealis near the poles.
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Chapter 3
Section 2 The Atmosphere
Energy Transfer in the Atmosphere
• Radiation – energy transferred as waves (sunlight)
• Conduction - transfer energy as heat through contact
• Convection - movement of matter due to differences in
density caused by temperature variations
– warm air rising and cool air sinking
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Chapter 3
Section 2 The Atmosphere
The Greenhouse Effect
• The greenhouse effect - warming of the lower
atmosphere that occurs when greenhouse gases
absorb, trap, and reradiate infrared radiation.
• Without the greenhouse effect, the Earth would be
too cold for life to exist.
• The most abundant greenhouse gases are water
vapor, carbon dioxide, methane, and nitrous oxide.
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Chapter 3
Section 3 The Hydrosphere and
Biosphere
The Hydrosphere
• The hydrosphere includes all of the water on Earth
– oceans, lakes, rivers, wetlands, polar ice caps,
groundwater, and clouds.
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Chapter 3
Section 3 The Hydrosphere and
Biosphere
The Water Cycle
• water cycle - continuous movement of water
– Evaporation –liquid to gas
– Condensation –gas to liquid
• Water vapor on dust particles form clouds.
– Precipitation - rain, snow, sleet, and hail
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Chapter 3
Section 3 The Hydrosphere and
Biosphere
Earth’s Ocean
• The largest ocean is the Pacific
• Deepest point, the Challenger Deep, in the Mariana
Trench.
– 11,033 m which is deeper than Mount Everest is tall
• Surface currents move clockwise north of the equator.
• Surface currents move counter-clockwise south of the
equator.
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Chapter 3
Section 3 The Hydrosphere and
Biosphere
Earth’s Oceans
• The 2nd largest ocean is the Atlantic
– half the size of the Pacific
– divided into a north and south half based on the
surface current flow
• The Indian Ocean is the 3rd largest ocean
• The smallest ocean is the Artic
– Mostly covered by floating ice
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Chapter 3
Section 3 The Hydrosphere and
Biosphere
Ocean Water
• Salinity is the amount of salt in a liquid.
– Salinity is low in places high precipitation or where
fresh water flows in to the sea.
– Salinity is high where water evaporates rapidly
and leaves the salt behind.
• Most salt in the ocean is NaCl.
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Chapter 3
Section 3 The Hydrosphere and
Biosphere
Temperature Zones
• The surface zone is warmed by the sun, while the
deep zone is just above freezing.
• Surface waters are mixed by waves/currents.
• In the middle is the thermocline, where the
temperature falls rapidly.
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Chapter 3
Section 3 The Hydrosphere and
Biosphere
A Global Temperature Regulator
• The ocean absorbs and releases heat slower than land,
so the temperature of the atmosphere changes slowly.
• Without the ocean, temperatures would be too extreme
for life to exist on Earth.
• Currents that circulate warm water bring moderate
climates to land.
– EX: the British Isles are warmed by the waters of the
Gulf Stream.
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Chapter 3
Section 3 The Hydrosphere and
Biosphere
Ocean Currents
• Surface currents: Wind driven movement of water
near the surface.
• Deep currents - movements of water that flow slowly
along the ocean floor.
– form when cold, dense water from the poles sinks
below warm, less dense water and flows toward the
equator.
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Chapter 3
Section 3 The Hydrosphere and
Biosphere
Fresh Water and River Systems
• Fresh water – most is locked in icecaps and glaciers,
the rest is in lakes, rivers, wetlands, the soil and
atmosphere.
• river system - network of streams that drains an area
of land.
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Chapter 3
Section 3 The Hydrosphere and
Biosphere
Ground water
• Aquifer: A rock layer that stores groundwater.
• Rain and melting snow sink into the ground, run off
the land and collect as groundwater.
• 1% of all the water on Earth, yet fulfills the need for
drinking water, and supplies agricultural and
industrial need.
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Chapter 3
Section 3 The Hydrosphere and
Biosphere
The Biosphere
• biosphere -part of Earth where life exists (11 km into
the ocean and 9 km into the atmosphere).
• When an organism dies, its nutrients become
available for other organisms.
• Plants need sunlight to produce their food, and form
the basis of the food chain.
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Chapter 3
Section 3 The Hydrosphere and
Biosphere
Energy Flow in the Biosphere
• Closed systems: Earth cannot exchange matter
outside of its boundaries.
• Open systems: Earth can exchange energy outside
of its boundaries.
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