Relative Dating Powerpoint

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Trilobite
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James Hutton- The first Geologist!
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Time and Geology
Sir Charles Lyell
Image source www.mnsu.edu/emuseum
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The Key to the Past

• Relative Time- this rock is older than that
• Principles Used to Determine Relative Age
• Unconformities
• Correlation
• The Standard Geologic Time Scale
• Index Fossils
• Absolute Time- this rock is 28 million years
  old
• Principles of radioactive decay
• Instruments
• The age of the Earth

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Important Figures in Geologic Time

• James Hutton (1726-1797) Native of Edinburgh,
  Scotland. Father of modern Geology. Published
  Theory of the Earth in 1785 in which he
  outlined that geological features and ancient
  rocks could be explained by present-day physical
  and chemical processes.
• Charles Lyell (1797-1875) Rebelled against
  prevailing thought, which was rooted in Biblical
  interpretation and Catastrophism. His main
  contribution was the development of
  Uniformitarianism (Actualism). The present is
  the key to the past
• Modern view holds that processes that operate
  today have shaped the Earth through Geological
  Time, but rates may not have always remained
  constant.

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Important Relative Age Dating Principles

• Original Horizontality all beds originally
  deposited in water formed close to horizontal

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Superposition within a sequence of undisturbed
sedimentary or volcanic rocks, layers become
younger, upward
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Lateral Continuity original sedimentary layers
extend laterally until it thins out at edges
rocks that are otherwise similar, but are now
separated by a valley or other erosional feature,
can be assumed to be originally continuous.
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Cross-cutting Relationships disruptions in any
rock sequence occurred after the youngest
established event in the undisturbed sequence Ie.
A rock or fault is younger than any rock (or
fault) through which it cuts
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Trip Through Time
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Sedimentary Deposition
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Intrusion
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Tilting Erosion
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Subsidence and New Marine Deposition
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Missing Formation
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Dike Event
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Erosion and Exposure
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Subsidence Deposition
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Fluvial Deposition
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Complex Subsurface Geology
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Contact Relations
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