Earth Science,
12e
Introduction to
Earth Science
Chapter 1
Earth Science
Encompasses all sciences that seek to
understand
• Earth
• Earth’s neighbors in space
Earth Science includes
• Geology – literally the “study of Earth”
• Oceanography – a study of the ocean
Earth Science
Earth Science includes
• Meteorology – the study of the atmosphere
and the processes that produce weather
• Astronomy – the study of the universe
People and the environment
Environment
• Surrounds and influences organisms
• Physical environment encompasses water,
air, soil, and rock
• Term “environmental” is usually reserved
for those aspects that focus on the
relationships between people and the
natural environment
People and the environment
Resources
• An important focus of the Earth sciences
• Includes water, soil, minerals, and energy
• Two broad categories
• Renewable – can be replenished (examples
include plants and energy from water and wind)
• Nonrenewable – metals (examples include
metals and fuels)
People and the environment
Population
• Population of the planet is growing rapidly
• Rate of mineral and energy usage has
climbed more rapidly than the overall
growth of population
Environmental problems
• Local, regional, and global
People and the environment
Environmental problems
• Human-induced and accentuated
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•
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Urban air pollution
Acid rain
Ozone depletion
Global warming
• Natural hazards
• Earthquakes
• Landslides
People and the environment
Environmental problems
• Natural hazards continued
• Floods
• Hurricanes
• World population pressures
Scientific inquiry
Science assumes the natural world is
• Consistent
• Predictable
Goal of science
• To discover patterns in nature
• To use the knowledge to predict
Scientific inquiry
An idea can become a
• Hypothesis (tentative or untested
explanation)
• Theory (tested and confirmed hypothesis)
• Paradigm (a theory that explains a large
number of interrelated aspects of the
natural world)
Scientific method
• Gather facts through observation
• Formulate hypotheses and theories
Scientific inquiry
Scientific knowledge is gained through
• Following systematic steps
•
•
•
•
Collecting facts
Developing a hypothesis
Conduct experiments
Reexamine the hypothesis and accept, modify,
or reject
• Theories that withstand examination
• Totally unexpected occurrences
Early evolution of Earth
Origin of Earth
• Most researchers believe that Earth and the
other planets formed at essentially the same
time
• Nebular hypothesis
• Solar system evolved from an enormous rotating
cloud called the solar nebula
• Nebula was composed mostly of hydrogen and
helium
Early evolution of Earth
Origin of Earth
• Nebular hypothesis (cont’d)
• About 5 billion years ago the nebula began to
contract
• Assumes a flat, disk shape with the protosun
(pre-Sun) at the center
• Inner planets begin to form from metallic and
rocky clumps
• Larger outer planets began forming from
fragments with a high percentage of ices
The Nebular hypothesis
Figure 1.8
Early evolution of Earth
Formation of Earth’s layered structure
• As Earth formed, the decay of radioactive
elements and heat from high-velocity
impacts caused the temperature to
increase
• Iron and nickel began to melt and sink toward
the center
• Lighter rocky components floated outward,
toward the surface
• Gaseous material escaped from Earth’s
interior to produce the primitive
atmosphere
Earth’s “Spheres”
Hydrosphere
• Ocean – the most prominent feature of the
hydrosphere
• Nearly 71% of Earth’s surface
• About 97% of Earth’s water
• Also includes fresh water found in streams,
lakes, and glaciers, as well as that found
underground
Earth’s “Spheres”
Atmosphere
• Thin, tenuous blanket of air
• One-half lies below 5.6 kilometers (3.5
miles)
Biosphere
• Includes all life
• Concentrated near the surface in a zone
that extends from the ocean floor upward
for several kilometers into the atmosphere
Earth’s “Spheres”
Solid Earth
• Based on compositional differences, it
consists of the crust, mantle, and core
• Divisions of the outer portion are based on
how materials behave
• Lithosphere - rigid outer layer
• Divisions of Earth’s surface – continents and
ocean basins
Earth’s layered structure
Figure 1.13
Earth system science
Earth is a dynamic body with many
separate but highly interacting parts or
spheres
Earth system science studies Earth as a
system composed of numerous parts, or
subsystems
System – any size group of interacting
parts that form a complex whole
Earth system science
System
• Closed systems are self-contained (e.g.,
an automobile cooling system)
• Open systems – both energy and matter
flow into and out of the system (e.g., a river
system)
Earth system science
Feedback mechanisms
• Negative-feedback mechanisms resist
change and stabilize the system
• Positive-feedback mechanisms enhance
the system
Earth as a system
• Consists of a nearly endless array of
subsystems (e.g., hydrologic cycle, rock
cycle)
Earth system cycles
Figure 1.21
Earth system science
Earth as a system
• Sources of energy
• Sun – drives external processes such as
weather, ocean circulation, and erosional
processes
• Earth’s interior – drives internal processes
including volcanoes, earthquakes, and
mountain building
• Humans are part of the Earth system