In geology, how long is an eon?
An eon (or aeon) is a long span of geologic time. Informally, eon often refers to a span of one billion years. In formal usage, eons are the longest portions of geologic time (eras are the second-longest, followed by period, epoch and age). Three eons are recognized: the Phanerozoic Eon (dating from the present back to the beginning of the Cambrian Period), the Proterozoic Eon, and the Archean Eon. Many argue that the Hadean time (4.6 to 4 billion years ago) is not a geological period (eon) as such. No rocks on the Earth are this old, except for meteorites. During Hadean time, the Solar System was forming, probably within a large cloud of gas and dust around the sun, called an accretion disc.
More Info:
en.wikipedia.org
What are your thoughts on this subject?
17 Comments
Marcel Tabor
kathybenson, 0.5 biilion is correct
ukmcfry
I always thought an eon was just a long period of time and not an actual length of time.
kathybenson
Its 0.5 billion so 500 million years so you wrte wrong. Sorry
skclary
Used 50/50 and the other choice was 100 years which, I knew was only a century!
Joanne Serin
Mary Clinton, it IS a billion. At least, mine said that was it.
Mary Clinton
Majority Vote got it wrong! I thought it was a Billion years!! I listened to M Vote!!
Mother of Dogs
I read somewhere that an eon was 0.5 billion years. Was so confused!
timwhitestevens
I found the explanation, very informative and interesting.
Mic Fenst
Ah, the word "informally" answers my question.
Roger Edwards
Bad question! Phanerozoic is 600 million years. An eon is not a set number of years by any definition!
Chris Brown
Etymology. From Ancient Greek αἰών (aiṓn, “age”).
John W Shreve
So I guess George Washington really wasn't president eons ago?
Doris Dallaire
I never knew just what an eon was other than a very long period of time. I learned something.
Howard Groopman
Using that definition, the Earth supposedly will die in about 5 eons, according to scientists.
Camille Curran
Great explanation. Learned something new!