Big Goals for Geologic Time/Stratigraphy

Scale/Magnitude/Hierarchy of Geologic Time

  • Earth is 4.5 billion years old- what does this mean
  • Resolution of geologic time—how accurately do we know time in different parts of the past; Our view of time is telescoped with a finer units closer to the present
  • How do we know/measure geologic time-methods
    • Absolute/Radiometric Dating
    • Relative Dating/stratigraphic principles
      • Cyclostratigraphy
      • Biostratigraphy
      • Magnetostratigraphy
      • Chemostratigraphy
  • Thresholds/benchmarks in geologic history; big natural changes/ what makes the major divisions in the geologic time scale

Earth has a history and is always changing- How do we know?

  • Reading the rock record
  • Proxies
  • Nature of rock record- composite nature of rock record (space for time)

How do geoscientists test theories and draw conclusions: what constitutes robustness?

  • Geoscientific method brings together multiple lines of evidence.
  • Critical evaluation of data.

Rates and processes in the Earth system

  • Gradual change vs abrupt events
  • External vs internal forcing
  • How do measure/know?
  • Cyclicity/cycles
  • Transgression/regression

Evolution of life

  • Relationship to human activity
  • What is evolution? What is evidence? Perception
  • Missing links/incomplete nature of rock record
  • Biotic response to global change

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