Roger Freedman • Robert Geller • William Kaufmann III
Universe
Tenth Edition
Chapter 9
The Living Earth
By reading this chapter, you will learn
9-1 What powers the motions
of the Earth’s atmosphere,
oceans, and land surfaces
9-2 How scientists have
deduced the layered
structure of our planet’s
interior
9-3 The evidence that the
continents are being
continuously moved and
reshaped
9-4 How life on Earth is protected
from subatomic particles
emitted by the Sun
9-5 How the evolution of life has
transformed the Earth’s
atmosphere
9-6 What causes the patterns of
weather in our atmosphere
9-7 How human civilization is
causing dramatic and adverse
changes to our planetary
habitat
9-1: Earth’s atmosphere, oceans and surface
are extraordinarily active
Earth’s Dynamic Oceans
Earth’s Dynamic Atmosphere
Earth’s Dynamic
Old and Young Rocks in the Grand Canyon
Old and Young Rocks in the Grand Canyon
Convection in the Kitchen
Convection in the Kitchen
The Greenhouse Effect
The Greenhouse Effect
Chemical Differentiation and Earth’s Internal Structure
Seismic Waves
9-2: Studies of earthquakes reveals Earth’s
layered interior structure
Earth’s Internal Structure and the Paths of Seismic Waves
Temperature and Melting Point of Rock Inside Earth
Fitting the Continents Together
The Breakup of the Supercontinent Pangaea
The Breakup of the Supercontinent Pangaea
The Breakup of the Supercontinent Pangaea
The Breakup of the Supercontinent Pangaea
9-3: Plate movement produces earthquakes, mountain
ranges and volcanoes that shape Earth’s surface
The Mid-Atlantic Ridge
The Mechanism of plate tectonics
The Separation of Two Plates
The Separation of Two Plates
The Collision of Two Plates
Igneous, Sedimentary and Metamorphic
Rocks
9-3: Earth’s magnetic field produces a
magnetosphere and reverses direction
Earth’s Magnetosphere
The Aurora
The Aurora
The Aurora
Simulation of Earth’s Magnetic Dynamo
Magnetic Stripes on the Ocean Seafloor
9-5: Earth’s atmosphere has changed
substantially over our planet’s history
The Increase in Atmospheric Oxygen
9-6: Like Earth’s interior, our atmosphere
has a layered structure
Temperature Profile of Earth’s Atmosphere
Circulation Patterns in Earth’s Atmosphere
9-7: A burgeoning human population is
profoundly altering Earth’s biosphere.
Earth’s Biosphere
Comparing Earth’s Atmosphere and Interior
The Human Population
The Deforestation of Amazonia
The Antarctic Ozone Hole
Atmospheric Carbon Dioxide is Increasing
Atmospheric CO2 and Changes in Global Temperature
Atmospheric CO2 and Changes in Global Temperature
Global Warming
A Melting Antarctic Ice Shelf
Key Ideas
• The Earth’s Energy Sources: All activity in the Earth’s atmosphere,
oceans, and surface is powered by three sources of energy.
• Solar energy is the energy source for the atmosphere. In the greenhouse
effect, some of this energy is trapped by infrared absorbing gases in the
atmosphere, raising the Earth’s surface temperature.
• Tidal forces from the Moon and Sun help to power the motion of the
oceans.
• The internal heat of the Earth is the energy source for geologic activity.
Key Ideas
• The Earth’s Interior: Studies of seismic waves (vibrations
produced by earthquakes) show that the Earth has a small,
solid inner core surrounded by a liquid outer core. The outer
core is surrounded by the dense mantle, which in turn is
surrounded by the thin low-density crust.
• Seismologists deduce the Earth’s interior structure by
studying how longitudinal P waves and transverse S waves
travel through the Earth’s interior.
• The Earth’s inner and outer cores are composed of almost
pure iron with some nickel mixed in. The mantle is composed
of iron rich minerals.
• Both temperature and pressure steadily increase with depth
inside the Earth.
Key Ideas
• Plate Tectonics: The Earth’s crust and a small part of its upper
mantle form a rigid layer called the lithosphere. The lithosphere is
divided into huge plates that move about over the plastic layer
called the asthenosphere in the upper mantle.
• Plate tectonics, or movement of the plates, is driven by convection
within the asthenosphere. Molten material wells up at oceanic
rifts, producing seafloor spreading, and is returned to the
asthenosphere in subduction zones. As one end of a plate is
subducted back into the asthenosphere, it helps to pull the rest of
the plate along.
Key Ideas
• Plate tectonics is responsible for most of the major features of
the Earth’s surface, including mountain ranges, volcanoes, and
the shapes of the continents and oceans.
• Plate tectonics is involved in the formation of the three major
categories of rocks: igneous rocks (cooled from molten
material), sedimentary rocks (formed by sediments in water),
and metamorphic rocks (altered by extreme heat and
pressure).
Key Ideas
•
The Earth’s Magnetic Field and Magnetosphere: Electric currents in the liquid outer
core generate a magnetic field. This magnetic field produces a magnetosphere that
surrounds Earth.
•
A bow-shaped shock wave, where the supersonic solar wind is abruptly slowed to
subsonic speeds, marks the outer boundary of the magnetosphere.
•
Most of the particles of the solar wind are deflected around the Earth by the
magnetosphere.
•
Some charged particles from the solar wind are trapped in two huge, doughnutshaped rings called the Van Allen belts. An excess of these particles can initiate an
auroral display.
•
Earth’s magnetic field flips regularly, but with an average of about 300,000 years
between reversals. These field flips are preserved in magnetizes rock on the ocean
seafloor.
Key Ideas
• The Earth’s Atmosphere: The Earth’s atmosphere differs
from those of the other terrestrial planets in its chemical
composition, circulation pattern, and temperature profile.
• The Earth’s atmosphere evolved from being mostly water
vapor to being rich in carbon dioxide. A strong greenhouse
effect kept the Earth warm enough for water to remain liquid
and to permit the evolution of life.
Key Ideas
• The appearance of photosynthetic living organisms led to our
present atmospheric composition, about four-fifths nitrogen and
one-fifth oxygen.
• The Earth’s atmosphere is divided into layers called the
troposphere, stratosphere, mesosphere, and thermosphere.
Ozone molecules in the stratosphere absorb ultraviolet light.
• Because of the Earth’s rapid rotation, the circulation in its
atmosphere is complex, with three circulation cells in each
hemisphere.
Key Ideas
• The Biosphere: Human activity is changing the Earth’s
biosphere, on which all living organisms depend.
• Industrial chemicals released into the atmosphere have
damaged the ozone layer in the stratosphere.
• Deforestation and the burning of fossil fuels are increasing
the greenhouse effect in our atmosphere and causing a
global warming of the planet.