Geologic Time Scale Quiz

Geologic Time Scale

• Definition: A system of chronological dating that relates geological strata to time.

• Major Divisions:

  • Eons: The largest time intervals, encompassing significant geological and biological events.
    • Hadean (4.6 - 4 billion years ago)
    • Archean (4 - 2.5 billion years ago)
    • Proterozoic (2.5 billion - 541 million years ago)
    • Phanerozoic (541 million years ago - Present)

• Eras within the Phanerozoic Eon:

  1. Paleozoic (541 - 252 million years ago)

     • Includes the Cambrian Explosion of life.
     • Major periods: Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian.

  2. Mesozoic (252 - 66 million years ago)

     • Age of reptiles, especially dinosaurs.
     • Major periods: Triassic, Jurassic, Cretaceous.

  3. Cenozoic (66 million years ago - Present)

     • Age of mammals and birds.
     • Major periods: Paleogene, Neogene, Quaternary.

• Periods and Events:

  • Each period of the geologic time scale is characterized by specific events, life forms, and environmental changes.
  • Notable mass extinction events:
    • Permian-Triassic Extinction (about 252 million years ago)
    • Cretaceous-Paleogene Extinction (about 66 million years ago)

• Relative Dating vs. Absolute Dating:

  • Relative Dating: Determines the order of past events without determining the actual age (e.g., layering of rocks).
  • Absolute Dating: Provides actual numerical dates using radiometric techniques (e.g., carbon dating).

• Importance:

  • Helps understand Earth's history, evolutionary biology, and the timing of geological events.
  • Aids in the exploration of natural resources and planning for geological hazards.

• Geologic Time Scale Visualization:

  • Often represented as a timeline, highlighting the major divisions and significant events, which provides a visual context for understanding Earth's historical timeline.

Geologic Time Scale

• Definition: A system of chronological dating relating geological strata to time.
• Major Divisions:
  • Eons: Largest time intervals, encompassing significant geological and biological events.
  • Hadean: (4.6 - 4 billion years ago)
  • Archean: (4 - 2.5 billion years ago)
  • Proterozoic: (2.5 billion - 541 million years ago)
  • Phanerozoic: (541 million years ago - Present)

Eras within the Phanerozoic Eon

• Paleozoic (541 - 252 million years ago)
  • Includes the Cambrian Explosion of life.
  • Major periods: Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian
• Mesozoic (252 - 66 million years ago)
  • Age of reptiles, especially dinosaurs.
  • Major periods: Triassic, Jurassic, Cretaceous
• Cenozoic (66 million years ago - Present)
  • Age of mammals and birds.
  • Major periods: Paleogene, Neogene, Quaternary.

Periods and Events

• Each period of the geologic time scale is characterized by specific events, life forms, and environmental changes.
• Notable mass extinction events:
  • Permian-Triassic Extinction (about 252 million years ago)
  • Cretaceous-Paleogene Extinction (about 66 million years ago)

Relative Dating vs. Absolute Dating

• Relative Dating: Determines the order of past events without determining the actual age (e.g., layering of rocks).
• Absolute Dating: Provides actual numerical dates using radiometric techniques (e.g., carbon dating).

Importance

• Helps understand Earth's history, evolutionary biology, and the timing of geological events.
• Aids in the exploration of natural resources and planning for geological hazards.

Geologic Time Scale Visualization

• Often represented as a timeline, highlighting the major divisions and significant events, providing a visual context for understanding Earth's historical timeline.