Precambrian Era2 by shuifanglj

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									        Arche
        an

                Protero
Hadea           zoic
n
Includes Earth’s
  history from
  creation up to 590
  million years ago.
 Makes up 7/8 of the
  Earth’s history
 The Precambrian
  starts with the
  solidifying of the
  Earths crust and
  ends with the first
  life forms.
 Represents about 87% of
  the Earth’s history.
 Broken down into 3
  periods
   Haden: 4.5 – 3.8 BYA
   Archean: 3.8 – 2.5
    BYA
   Proterozoic: 2.5 - .5
    BYA
   4500 to 3800 million years ago
   Volcanic activity
   Meteor impacts
   Unaware of life that existed during this
    time
 The Hadean or “Hades like”
  period was from 4.5 to 3.8
  billion years ago.
 Between the ages of the
  oldest extraterrestrial rocks
  and the oldest of our own.
2500 to 3800 million years ago
 Earth cooled down
 Life began in the ocean
   Blue-green algae floating in the
    ocean
 Islands from the volcanoes are
  the only land surfaces
 Age of the oldest rocks on Earth
 From 3.8 to 2.5
  Bya.
 The surface had
  cooled and water
  vapor condensed
  forming a global
  ocean.
 Active volcanism
  formed island
  chains.
 Earth’s crust during
  Archean time was much
  thinner and hotter, and
  more unstable.
 Earth may have still been
  cooling off.
 Then atmosphere is steamy
  and hot.
 Evidence in Lake Superior
  area and Scandinavia of
  violent volcanism.
 This means the Earth was
  still forming its harder,
  more stable crust.
 All life during this Era was
  aquatic.
 Life began as bacteria,
  photosynthetic, blue
  green algae.
 Top: a Stromatolite.
 Middle: underwater
  depiction of late
  Precambrian.
 Bottom: photosynthetic
  bacteria.
First life: Single-celled prokaryotic organisms with no DNA
      Earliest fossils


                                              Blue-green algae




Phylum of bacteria that obtain their energy
through photosynthesis.
 These photosynthetic
 bacteria were
 unicellular, but would
 often grow together in
 great strings and
 “mats” that would float
 about in the oceans
 and began to
 colonize rock
 formations.
During the Archean, and through out the Proterozoic: photo
synthetic bacteria known as Cyanobacteria began
colonizing the oceans.
Attached, lithified sedimentary growth
Structures. Mats of algae overlaying each
other to form layered fossils.




                                            Formed by the trapping,
                                            binding, and cementation
                                            of sedimentary grains by
                                            microorganisms, especially
                                            Cyanobacteria.
 These layered
 fossils show
 generations of
 bacteria preserved
 within the rock.
 Stromatolites grow in
  arches, but mostly in
  layered formations, and
  domes.
 Shallow water pools are
  vital to the formation of
  Stromatolites.
 These living fossils still
  exist today growing in
  Australia, Yellowstone
  and few other places.
 Hamlin Pool, Australia.
 In Yellowstone National
 Parks octopus spring
 layered Stromatolites
 formed by multiple
 bacteria are growing.
 In Yellowstone the
 stratified layers of different
 bacteria begin to show
 cylindrical and dome
 shaped replication of
 Stromatolites.
      Banded Iron
  Archaean (2.87 bya)              Stromatolites
      South Pass,               Archaean (2.58 bya)
       Wyoming              Lower Whalen Group, Wyoming




  Brecciated Banded Iron      Hadrophycus Immanus stromatolites
   Archaean (2.73 bya)        Archaean (2.58 bya)
Jackson County, Wisconsin     Medicine Bow Range, Wyoming
 542 to 2500 million years ago
 The Proterozoic Period took
  place between 2.5 Bya to 570
  Mya.
 During this period island chains
  grouped together and expanded
  from volcanic activity and plate
  tectonics.
 Cores or shields, which are
  shallow igneous formations from
  the Precambrian are
  incorporated in every present
  day continent.
 They all come from the original
  super continent.
       The early continents can be dated by determining
        the age of the oldest continental rocks that have
        not been reheated or chemically altered.
       Atmosphere was mostly nitrogen with little water
        vapor and carbon dioxide
       Two super continents
         Land masses formed by collisions of many islands
          made by volcanoes.
         Very cold, with huge bluish glacial ice sheets
 Microscopic organisms
 Most organisms lived in the water.
 The were soft bodies.
 No hard parts for fossilization.
 Over time, primitive
  cells evolved into
  multi-cellular life.
 By the end of the
  Precambrian there
  were life forms called
  Metazoans. They all
  had soft bodies.
   Jellyfish,
   flat worms,
   annelid worms, etc.
              *By the end of the
              Precambrian there
              were life forms
  Worms
              called Metazoans.


            Seapens




Jellyfish
 The cores that formed the super
 continent became the bases
 upon which our current
 continents are formed. There is
 a core or “shield” present within
 each.
                         The metamorphic rocks exposed
Many Igneous rocks are
                         Along this route consist of
Precambrian Granites.
                         Precambrian schist and gneiss

								
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