Nathan A. Noble

Precambrain FactsThe Precambrian is divided into three time

periods.The Hadean, Archean and the ProterozoicThe Precambrian makes up 7/8 of the Earth’s

historyLast 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 FactsThe 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 factsArchean 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

CyanobacteriaThrough photosynthetic activity,

cyanobacteria fundamentally altered the Archean atmosphere through the production of a valuable waste product--free oxygen.

Proterozoic

Proterozoic factsOxygen 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 highlightTowards 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.

PrecambrianThe 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 citedFirst to pictures of Hadean Earthhttp://www.vredefortstructure.org/

engtimeline04.htmPicture of oxygenhttp://blog.wired.com/photos/uncategorized/

2007/10/09/oxygen_logo.jpgPicture of cellhttp://blog.wired.com/photos/uncategorized/

2007/10/09/oxygen_logo.jpghttp://www.ucmp.berkeley.edu/bacteria/bacterialh

.htmlhttp://www.ucmp.berkeley.edu/precambrian/prote

rozoic.htmlhttp://facstaff.gpc.edu/~pgore/geology/geo102/

precamb.htm