Birth of the Universe by yurtgc548


									   Adjusting Your Sense of Time

Time scales of everyday life:
  When is my next class? (hours)
  Where's the party this weekend? (days)
  What will I do when I graduate? (years)
Historians and Archeologists:
  What happened 100s to 1000s of years
      Adjusting Your Sense of Time
Time Scales of a Geologist:
  Age of the Earth – 4,500,000,000 years
    • Bear’s start on their 0 yard line
  Cambrian “explosion” of life – 500,000,000 years
    • Devin Hester returns kickoff to Packer’s 11.4
      yard line
      Adjusting Your Sense of Time
Time Scales of a Geologist:
  Dinosaurs go extinct – 65,000,000 years
     • Kyle Orton scrambles to 1.4 yard line
  Steve Van der Hoven's age – 45 years
     • Pass interference advances ball to 0.0001
       yard line
   Adjusting Your Sense of Time
Most geologic process occur too
 slowly to directly observe.

                                  Fig. 1.4
   Principle of Uniformitarianism

We observe how geologic processes
 operate today, and use this to
 explain how features formed in the
Processes must conform to natural
Allows us to make interpretations of
 events that were not observed.
   Principle of Uniformitarianism

 Modern ripple    Ancient ripple marks
marks on a beach.  formed on a beach?

          Fig. 1.8   Fig. 1.8
  Uniformitarianism to Predict the Future

Using past volcanic       Predicting areas
eruptions to predict   vulnerable to volcanic
   future ones.              hazards.
 Can Uniformitarianism be applied
        to other planets?
Evidence for water on Mars:
Layers implying deposition by running
    Uniformitarianism on Mars?

Evidence for water on Mars:
Jarosite – a mineral that forms in wet,
  acidic soils on Earth.
Do you think it is reasonable to apply
 the Principle of Uniformitarianism to
 the study of Mars?
  Introduction of Plate Tectonics

An old idea, but only widely accepted
 since the 1960s.
A unifying theory, explains almost all
 geologic processes.

       Fig. 1.10
  Introduction of Plate Tectonics
Plate Tectonics explains:
Why/where earthquakes and volcanoes
Patterns of mountain ranges.

    Fig. 12.7
         Plate Tectonics Basics

Outer layer of Earth is rigid and broken
  into pieces (plates).
Internal heating causes
                                      Fig. 1.15
inner layers to circulate.
Circulation causes plates
to move around.
       Plate Tectonics Basics

Tectonic cycle – new crust created,
 older crust recycled.
Plate Tectonics Basics

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