The precambrian

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The precambrian

• Nathan A. Noble

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Precambrain Facts

• The Precambrian is divided into three time
  periods.
• The Hadean, Archean and the Proterozoic
• The Precambrian makes up 7/8 of the Earths
  history
• Last April, a 5th grader pointed out to the
  Smithsonian Natural History Museum that their
  Tower of Time was incorrect by referring to the
  Precambrian as an Era when it really is a
  supereon. The Smithsonian corrected the 27 year
  old mistake.

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Hadean
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Hadean Facts

• The Hadean gets its name from the mythological
  underground of Hades.
• This is the period during which the Earth's crust
  was formed. 
• This crust melted and reformed numerous times,
  because it was continuously broken up by gigantic
  magma currents that erupted from the depths of
  the planet, tore the thin crust, and then cooled
  off on the surface before sinking again into the
  heart of the Earth.

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Hadean Highlights The Moon
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(No Transcript)
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Archean
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Archean facts

• Archean Earth differed greatly from our modern
  Earth not only in tectonic activity but also with
  respect to the atmosphere.
• The Archean is known as the "Age of Prokaryotes",
  the first documented forms of life.
• Prokaryotes are simple, single-celled organisms
  that lack a nucleus, mitochondria and organized
  cell function.
• Prokaryotes have a distinct advantage over other
  life forms in that they reproduce asexually,
  which sounds boring but is quite effective.

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Archean Highlights
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Cyanobacteria

• Through photosynthetic activity, cyanobacteria
  fundamentally altered the Archean atmosphere
  through the production of a valuable waste
  product--free oxygen.

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Proterozoic
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Proterozoic facts

• Oxygen starts to build up and take up residence
  in the Earths atmosphere.
• Bacteria that are exposed to the now oxygen
  saturated atmosphere are dying off. However, the
  bacteria that survive on the edges of O2 zone,
  are evolving into aerobic bacteria.
• Single cell organisms called eukaryotes evolved
  from aerobic bacteria. These new organism use O2
  as a new and powerful source of energy.

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Porterozoic highlight

• Towards the very end of the porterozoic, some
  multicelluar organism called trilobites came to
  be.
• Trilobites are very well-known, and possibly the
  second-most famous fossil group, after the
  dinosaurs they are already highly diverse and
  geographically dispersed.
• Because of their diversity and an easily
  fossilized exoskeleton, more of these fossils
  have been found than any other Porterozoic
  organisms.

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Precambrian

• The Hadean was a time when the Earth was just
  starting to form.
• Archean saw the first life forms that could trap
  energy from the sun and they could also reproduce
  themselves.
• The Proterozoic produced the first multicelluar
  organism that could be easily fossilized.

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Works cited

• First to pictures of Hadean Earth
• http//www.vredefortstructure.org/engtimeline04.ht
  m
• Picture of oxygen
• http//blog.wired.com/photos/uncategorized/2007/10
  /09/oxygen_logo.jpg
• Picture of cell
• http//blog.wired.com/photos/uncategorized/2007/10
  /09/oxygen_logo.jpg
• http//www.ucmp.berkeley.edu/bacteria/bacterialh.h
  tml
• http//www.ucmp.berkeley.edu/precambrian/proterozo
  ic.html
• http//facstaff.gpc.edu/pgore/geology/geo102/prec
  amb.htm