Chapter 1 Introduction to Earth History

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Chapter 1Introduction to Earth History

• Geology the study of the Earth
• Two major branches
• Physical geology Earth materials and processes
• Historical geology origin changes of Earth
  life through time

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• A side note
• We say geology is the study of the Earth
• Geologic knowledge is also applied to the study
  of the surfaces of other planets, moons,
  asteroids

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A meteorite found on the Antarctic Ice Cap. (Is
that a facial profile on the left side? A real
space man?)
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• Why study historical geology
• Knowing what happened on the Earth in the past
  can help us predict the future
• Explains the why and where of key mineral
  deposits (metals, oil gas, coal, etc)
• Looking at the evidence regarding past climate
  helps to evaluate possible current changes
• As humans, were just downright curious

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• Geology is a science, and as such, employs the
  scientific method
• A systematic way to find
• Answers to questions
• Solutions to problems
• Evidence to prove or disprove ideas beliefs

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Usually start with several hypotheses
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• Another side note
• Scientist theory is something having a high
  probability of being correct
• Layman theory implies a lack of knowledge, or
  a mere guess

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• Scientific investigation does not end with a
  theory
• Further tests are formulated and run, as
  technology and science advances
• If the theory survives much testing, becomes a
  scientific law
• e.g., law of gravitational attraction

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• Three major themes in Earth history
• Deep time
• Plate tectonics
• Evolution of life

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• Deep time
• How old is the Earth?
• Several lines of evidence, to be covered soon
• Relative age
• Absolute age

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• Plate tectonics
• A fairly recent development in Earth science (it
  was a hotly debated hypothesis when I was an
  undergrad)
• Now held as a theory, explains many observations
  that previously seemed unrelated
• Again, more details forthcoming

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The quick and dirty view of plate tectonics
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• Evolution of life
• Actually, has more to do with biology
• But, changes in life recorded in the fossil
  (rock) record
• These changes important in deciphering the
  various ages in geologic history
• The changes correspond with changes on the
  Earths surface
• Have even been suggestions that life itself has
  helped form the present face of the Earth

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A fossil