The Science of
PHYSICAL GEOLOGY
“If your mind is empty, it is always ready for anything; it
is open to everything.” Zen Proverb
The Science of Geology
• Geology is the science that pursues
an understanding of planet Earth
• Physical Geology – Examines the
materials composing Earth and seeks
to understand the many processes
that operate beneath and upon its
surface.
• Historical Geology – Seeks an
understanding of the origin of Earth
and its development through time.
Why Study Geology?
• Humans and the
natural environment
are interrelated.
– Natural Hazards
– Resources – Energy,
Water, Agriculture, etc.
– Environmental Issues
• Understanding past geologic
events will help us predict
future geologic events.
Humans ask questions to
understand the natural environment
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How did the Universe and our Solar System form?
How did the Earth form? How do rocks form?
What is Plate Tectonics?
Why do earthquakes and volcanic eruptions occur?
What governs the location of mountain ranges?
Where do we get energy resources from?
How are gemstones formed?
Where do we get drinking water from?
What factors provide for the best agricultural areas?
What caused the ice ages? What causes global
warming?
Curiosity Leads to Exploration
The Answers are Written in
the Rocks
Rocks and Fossils are
important tools for geologists
that tell a story of what Earth
like in the past.
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Life Forms (flora and fauna)
Plate Tectonics
Mountain Building
Volcanic Eruptions
Age Dating
Paleoclimate
Extinctions
Global Sea Level
Rise and Fall
Ice Ages
How do geologists read the story
recorded in the rock and fossil record?
Science operates through the
use of the Scientific Method
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“A poverty of ideas is a more serious deficiency than
faulty reasoning” Robert Magnan
Observe
Raise Question
Form Hypothesis
Test Hypothesis
Gather Data
Modify Hypothesis
Retest Hypothesis
Limits of Science
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Questions (hypotheses) must be testable.
Results must be repeatable.
No moral or aesthetic judgments.
Can only test the natural, physical world.
Scientific discoveries may be controversial…
especially when they are first made.
What is a Hypothesis?
What is a Theory?
What is a Hypothesis?
• Hypothesis – A tentative (or
untested) explanation.
• A hypothesis that survives
repeated testing and challenges,
and is supported by a large body
of evidence, may be elevated to
the status of a Theory.
What is a Theory?
• Theory – A well-tested and widelyaccepted explanation of natural
phenomenon that the scientific
community agrees best explains
certain observable facts.
Examples of Theories:
Theory of Relativity
Plate Tectonics Theory
Evolutionary Theory
Atomic Theory
Cell Theory
What is a Theory?
• It is important to understand that the term “theory” has very
different meanings to scientists and to the general public.
• To a scientist,
– A theory is not just a wild idea, a guess, or a belief.
– It is based on objective facts.
– Theories have survived close examination, and can be accepted
with confidence.
– A theory represents knowledge that has very high probability of
being correct.
– A theory remains open to tests and revision….that can make
theories stronger/weaker.
• Whereas, in common language,
– “Theory” implies a lack of knowledge or a guess, conjecture,
opinion, speculation. In this usage, a theory is not necessarily
based on facts.
What is Scientific Law?
• Paradigm – A theory may become a
paradigm (a predominant worldview in
the realm of human thought) or
• Scientific Law after further testing and
acceptance.
• Example: Law of Gravity
Peer-Reviewed Journals –
Primary Literature
Science
Magazines
Secondary Literature
Summary of Scientific Method
1. Make observations:
• The shape of Earth’s continents appear to fit
together like pieces of a jigsaw puzzle.
2. Identify a question or problem:
• At some time in the past, were the continents
joined together forming one large land mass?
3. Develop working hypothesis (idea to explain
the observations):
• During Earth's history, the continents were joined
together into one giant supercontinent (called
Pangaea meaning "All Lands" in Greek).
Summary of Scientific Method
4. Determine ways to test the hypothesis by
experimenting and either accept, reject, or modify
the hypothesis:
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Develop tests that support or disprove that the continents
were once joined.
Develop tests that support or disprove that the continents
have moved (and may still be in motion).
The simplest explanation is typically the best.
What is some of the information we can use to do this?
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Fit of Continents
Rock Types
Rock Structures
Fossils
Paleoclimate Data
Apparent Wandering of the Earth's Polar Regions
Geodetic evidence that continents are moving at a
measurable rate
Summary of Scientific Method
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Collect Data
Analyze Data:
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Interpret Data:
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Try to piece continents back together based on data
collected
Are there trends or correlations?
Support or refute hypothesis and develop new
hypothesis, if appropriate.
9. Repeat Steps 4 thru 10.
10. Only after repeated testing of the hypothesis, in
which it gains considerable experimental or
observational support, is it accepted and a theory
is established.
11. A theory ultimately may become a paradigm or
scientific law.