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Understanding time permits assigning an age to…
The Geologic Time Scale
Planet Earth is over 4.5 billion years old - that's a loooong time! Just as we currently divide time up by years, months, and days, Geologists divide up those 4.5 billion years into segments. The start/end point for each is usually based upon the appearance or dissappearance of a species.
Eons are the longest division of geologic time. There are four: Hadean, Archean, Proterozoic, and Phanerozoic
Eons are subdivided into Eras.
Eras are divided into shorter units called periods, and periods are divided into epochs. The times for eons and eras are the same worldwide, but periods and epochs can be different. As we get closer to the present time, the more information we have and regional differences are more apparent.
So, Where Are We Today?
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|CSULA Department of Geosciences and the Environment|
|Pasadena City College Department of Geology|
|© Sonjia Leyva 2018|