Geology

Precambrian

March 9, 2013, 9:49 pm
Content Cover Image

Weathered Precambrian pillow lava in the Temagami greenstone belt in the Eastern Canada Shield. CC-attribution

This article on the Precambrian was written by Ben Waggoner; A.G.C.

According to geological constructs, the Precambrian commenced at the outset of the Earth's existence. Comprehending that vastness in time is no easy task. John McPhee, in his book Basin and Range, recounts a nice illustration of what this sort of time means. Stand with your arms held out to each side and let the extent of the earth's history be represented by the distance from the tips of the fingers on your left hand to the tips of the fingers on the right. Now, if someone were to run a file across the fingernail of one's right middle finger, then the time that humans have been on the earth would be erased.

This article is written at a definitional level only. Authors wishing to improve this entry are inivited to expand the present treatment, which additions will be peer reviewed prior to publication of any expansion.

Nearly four thousand million years passed after the Earth's inception before the first animals left their traces. This stretch of time is called the Precambrian. To speak of "the Precambrian" as a single unified time period is misleading, for it makes up roughly seven-eighths of the Earth's history. During the Precambrian, the most important events in biological history took place. Consider that the Earth formed, life arose, the first tectonic plates arose and began to move, eukaryotic cells evolved, the atmosphere became enriched in oxygen -- and just before the end of the Precambrian, complex multicellular organisms, including the first animals, evolved.

 

caption (Source: UCMP)

 

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Citation

(2013). Precambrian. Retrieved from http://www.eoearth.org/view/article/51cbeea97896bb431f6996f0

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