Transcript Volcanoes and Igneous Activity Earth

Earth Science, 6e
Edward J. Tarbuck &
Frederick K. Lutgens
Earth's “Spheres"
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
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
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)
The hydrologic cycle
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
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
Growth of world population
People and the environment
Environmental problems
• Human-induced and accentuated
•
•
•
•
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
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 continued
• About 5 billion years ago the nebula began to
contract
• Assumes a flat, disk shape with the protosun (preSun) 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
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
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
End of Introduction