© 2011 pearson education, inc. tarbuck & lutgens earth: an introduction to physical geology,...
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© 2011 Pearson Education, Inc.
Tarbuck & Lutgens
Earth: An Introduction to Physical Geology,
10e
© 2011 Pearson Education, Inc.
Stan Hatfield
Southwestern Illinois College
An Introduction to GeologyEarth, 10e - Chapter 1
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Geology is the science that pursues an understanding of planet Earth.
Physical geology examines Earth materials and seeks to understand the many processes that operate on our planet.
Historical geology seeks an understanding of the origin of Earth and its development through time.
The Science of Geology
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Geology, people, and the environment Many important relationships exist
between people and the natural environment.
Problems and issues addressed by geology include: Natural hazards, resources, world population
growth, and environmental issues
The Science of Geology, Continued
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The magnitude of geologic time Involves vast times—millions or billions of
years An appreciation for the magnitude of
geologic time is important because many processes are very gradual.
Geologic Time
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Some historical notes about geology The nature of Earth has been a focus of study
for centuries. Catastrophism Uniformitarianism—the physical, chemical,
and biologic laws that operate today have operated throughout the geologic past.
The Science of Geology
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Geologists are now able to assign fairly accurate dates to events in Earth history.
Relative dating and the geologic time scale Relative dating means that dates are placed
in their proper sequence or order without knowing their specific age.
Superposition—in a sequence of sedimentary rocks or lava flows, the youngest layer is on top and the oldest layer is on the bottom.
Geologic Time
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Superposition is well illustrated in the rocks of the Grand Canyon
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Relative dating and the geologic time scale Principle of fossil succession—fossil organisms
succeed one another in a definite and determinable order. Therefore, any time period can be recognized by its fossil content.
Geologic Time
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The Geologic Time Scale
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Science assumes the natural world is consistent and predictable.
The goal of science is to discover patterns in nature and use the knowledge to make predictions.
Scientists collect data through observation and measurements.
The Nature of Scientific Inquiry
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How or why things happen are explained using: Hypothesis—a tentative (or untested)
explanation Theory—a well-tested and widely accepted
view that the scientific community agrees best explains certain observable facts
The Nature of Scientific Inquiry, Continued
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Scientific methods involves: Gathering facts through observations Formulation of hypotheses and theories
There is no fixed path that scientists follow that
leads to scientific knowledge.
The Nature of Scientific Inquiry, Continued
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Earth is a planet that is small and self-contained.
Earth’s four spheres are:
1. Hydrosphere
2. Atmosphere
3. Biosphere
4. Geosphere
A View of Earth
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A View of EarthFrom Apollo 17
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Earth is a dynamic planet with many interacting parts or spheres.
Earth system science: Aims to study Earth as a system composed of
numerous interacting parts, or subsystems Employs an interdisciplinary approach to
solve global environmental problems
Earth as a System
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What is a system? Any size group of interacting parts that form
a complex whole Open vs. closed systems
Feedback mechanisms Negative feedback maintains the status quo. Positive feedback enhances or drives
changes.
Earth as a System, Continued
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Cycles in the Earth System Hydrologic cycle Rock cycle
An interface is a common boundary where different parts of a system come in contact and interact.
Earth as a System, Continued
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The Interface between the Hydrologic and Rock Cycles
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The Earth system is powered by the Sun that drives external processes in the following:
Atmosphere Hydrosphere At Earth’s surface
The Earth system is also powered by Earth’s interior.
Earth as a System
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Origin of planet Earth Most researchers believe Earth and other planets
formed at essentially the same time. Nebular hypothesis
Solar system evolved from an enormous rotating cloud called the solar nebula
Composed of hydrogen and helium Nebula began to contract about 5 billion years ago.
Early Evolution of Earth
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Origin of planet Earth Nebular hypothesis
Assumes a flat, disk shape with the protosun (pre-Sun) at the center
Inner planets begin to form from metallic and rocky substances.
Larger outer planets began forming from fragments of ices (H2O, CO2 , and others).
Early Evolution of Earth, Continued
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The Nebular Theory
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Formation of Earth’s layered structure Metals sank to the center. Molten rock rose to produce a primitive
crust. Chemical segregation established the three
basic divisions of Earth’s interior. A primitive atmosphere evolved from gases
in Earth’s interior .
Early Evolution of Earth
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Layers defined by composition: Crust Mantle Core
Layers defined by physical properties: Lithosphere Asthenosphere Mesosphere Inner and outer core
Earth’s Internal Structure
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Earth’s Layered Structure
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Earth’s surface: Continents Oceans
Continents: Mountain belts
Most prominent feature of continents
The stable interior Also called a craton—composed of shields and
stable platforms
The Face of Earth
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Earth’s Mountain Belts, Stable Platforms, and Shields
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Ocean basins: Continental margins
Includes the continental shelf, continental slope, and the continental rise
Deep-ocean basins: Abyssal plains Oceanic trenches Seamounts
The Face of Earth
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Ocean basins: Oceanic ridge system
Most prominent topographic feature on Earth Composed of igneous rock that has been fractured
and uplifted
The Face of Earth, Continued
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Basic rock types:• Igneous rocks
Cooling and solidification of magma (molten rock) Examples include granite and basalt.
• Sedimentary rocks Accumulate in layers at Earth’s surface Sediments are derived from weathering of preexisting
rocks
Rocks and the Rock Cycle
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Granite (an Igneous Rock) in Yosemite National Park, CA
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Basic rock types:• Sedimentary rocks
Examples include sandstone and limestone.
• Metamorphic rocks Formed by “changing” preexisting igneous, sedimentary,
or other metamorphic rocks Driving forces are heat and pressure. Examples include gneiss and marble.
Rocks and the Rock Cycle
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Sandstone (a Sedimentary Rock) in Zion National Park, Utah
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The rock cycle: one of Earth’s subsystems• The loop that involves the processes by which one rock
changes to another. • Illustrates the various processes and paths as Earth
materials change both on the surface and inside the Earth
Rocks and the Rock Cycle
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The Rock Cycle
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End of Chapter 1