Transcript PowerPoint - Science A 2 Z

Nathan A. Noble
Precambrain Facts
 The Precambrian is divided into three time periods.
 The Hadean, Archean and the Proterozoic
 The Precambrian makes up 7/8 of the Earth’s 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.
Hadean
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.
Hadean Highlights: The Moon
Archean
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.
Archean Highlights
Cyanobacteria
 Through photosynthetic activity, cyanobacteria
fundamentally altered the Archean atmosphere
through the production of a valuable waste product-free oxygen.
Proterozoic
Proterozoic facts
 Oxygen starts to build up and take up residence in the
Earth’s 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.
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.
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.
Works cited
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First to pictures of Hadean Earth
http://www.vredefortstructure.org/engtimeline04.htm
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.html
http://www.ucmp.berkeley.edu/precambrian/proterozoic.h
tml
http://facstaff.gpc.edu/~pgore/geology/geo102/precamb.ht
m