Chronostratigraphy and Geologic Time

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Chronostratigraphy and Geologic Time
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Terms

• Chronostratigraphy stratigraphic units defined
  and delineated on the basis of time
• Geologic time units based on time, relative or
  absolute.
• Conceptual units rather than actual rock units
• Look at Figure 15.1

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Geologic Time units

• Stratotypes unit based on actual rock sections,
  units independent of reference rock sections
• Isochronous units rock units formed during the
  same span of time, bounded by synchronous
  surfaces, each point has the same age

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Time units and Time Rock units
Table 15.1
Eon Eonothem
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Time units

• Eons
• Phanerozoic Evident life
• Proterozoic Early Life
• Archean Archaic
• Hadean Fire, Hades

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Time units 2

• Eras of Phanerozoic Eon
• Cenozoic Modern Life
• Mesozoic Middle Life
• Paleozoic Ancient Life

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Smaller Time units

• Periods
• Epochs
• Ages

Table 15.2 in your textbook, know
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Cambrian Silurian controversy

• Adam Sedgwick Cambrian
• Cambria Wales
• Rodrick Impey Murchison Silurian
• Silures Celtic tribe
• Charles Lapworth
• Ordovices Celtic tribe
• Sedgewick and Murchison - Devonian
• Devon England

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Absolute Ages

• Radiochronology
• Parent Isotope
• Daughter Isotope
• Half-life

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Correlation by Stable Isotope events

• Oxygen isotopes
• Oxygen-isotope stratigraphy (Figure 15.10)
• Carbon isotopes
• Sulfur isotopes

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So how do we use these dates?
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Time and Place Words

• Time
• Late
• Early
• Middle
• Medial
• During
• Sometimes
• Sequence
• Before
• After
• Young
• Old
• Pre-
• Post
• When
• Often
• occasionally

• Place
• Upper
• Lower
• Central
• Middle
• In
• Someplace
• Succession
• Below
• Above
• High
• Low
• Sub-
• Super-
• Where
• Abundant
• locally