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Exploring Geologic Time

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Exploring Geologic Time Geologic Time Scale The geologic time scale a calendar of Earth history Subdivides geologic history into units Originally created ... – PowerPoint PPT presentation

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Title: Exploring Geologic Time


1
Exploring Geologic Time
2
Geologic Time Scale
  • The geologic time scale a calendar of Earth
    history
  • Subdivides geologic history into units
  • Originally created using relative dates
  • Structure of the geologic time scale
  • Eon the greatest expanse of time
  • Era an eon is divided into eras

3
Geologic Time
  • Chapter 8

4
The 4.6 billion years of Earths history can be
divided into 2 major time segments called eons.
  • Precambrian Time
  • Hadean, Archaen, Proterozoic Eons
  • 4600 to 542 mya
  • This boundary continually changes as older soft
    bodied fossils are recognized
  • Phanerozoic Eon
  • 543 mya to present
  • mya means million of years ago

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Each era can be subdivided into periods.
Periods can be subdivided into epochs. Each
time segment is characterized by changes in
landforms (tectonics changes), climate, and in
life forms.
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Precambrian Time Age of Earth Forming
  • 85 of Earths history
  • Intense volcanic activity oceans form meteorite
    bombardment
  • Atmosphere develops
  • Life begins with unicellular organisms
    (blue-green algae and bacteria) and evolves to
    multi-cell organisms like worms
  • Few fossils exist because most did not have hard
    parts

10
The Phanerozoic Eon began when life developed
hard bodies. The Phanerozoic Eon is divided
into time segments called eras.
  • Paleozoic 542 Mya to 251 Mya
  • Mesozoic 251 Mya to 65 Mya
  • Cenozoic 65 Mya to present

11
The Paleozoic Era Age of Ancient Plants and
Animals
  • First supercontinent (Rodinia) with break up and
    finally formation of Pangaea
  • Six periods are marked by significant differences
    in lifeforms
  • Appearance of fish, insects, amphibians, and some
    reptiles

12
The Mesozoic Era Age of Dinosaurs
  • Known as age of reptiles dinosaurs are prominent
    life forms
  • Last part of this period (Cretaceous) witnesses
    large-scale extinction of marine and flying
    reptiles as well as dinosaurs extinction may be
    due to massive asteroid collision with Earth and
    massive volcanic eruptions
  • Pangaea breaks up

13
The Cenozoic Era Age of Mammals and Flowering
Plants
  • Age of mammals and flowering plants
  • Climates cool generating widespread glaciation
  • Humans evolve
  • High level of tectonic activity as plates
    separate and evolve

14
Diagram
  • http//www.bobainsworth.com/fossil/Earths_timeline
    _dw1.swf
  • Geologic Time

15
Geologic Column in Rock Strata
16
Information about rocks of a particular geologic
time can be displayed on a map called a geologic
map.
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