Geologic time scale - Wikipedia
网页There are four formally defined eons: the Hadean, Archean, Proterozoic and Phanerozoic. [2] An era is the second largest geochronologic time unit and is equivalent to a chronostratigraphic erathem.
Eon Definition & Meaning - Merriam-Webster
网页borrowed from Late Latin aeōn "age (in the world's history), evil spirit (in Gnosticism)," borrowed from Greek aiṓn "lifetime, long period of time, age" — more at aye entry 3. First …
Eons | PBS
网页Preview: EONS. Welcome to Eons! Join hosts Michelle Barboza-Ramirez, Kallie Moore, and Blake de Pastino as they take you on a journey through the history of life on Earth.
Geologic Time Scale: A List of Eons, Eras, and Periods - ThoughtCo
网页2020年2月28日 · The geologic time scale is a system used by scientists to describe Earth's history in terms of major geological or paleontological events (such as the formation of a new rock layer or the appearance or demise of certain lifeforms). Geologic time spans are divided into units and subunits, the largest of which are eons.
Geologic time | Periods, Time Scale, & Facts | Britannica
网页2024年9月13日 · The geologic time scale is the “calendar” for events in Earth history. It subdivides all time into named units of abstract time called—in descending order of duration— eons, eras, periods, epochs, and ages.
Geologic Time Scale : Divisions, Periods and Eons - Geology Science
网页2023年12月6日 · The two eons in the Geologic Time Scale are the Precambrian eon and the Phanerozoic eon. The Precambrian eon covers the first four billion years of Earth’s history and is divided into three eras: the Hadean, Archean, and Proterozoic.
Eon | Precambrian, Paleozoic & Mesozoic | Britannica
网页eon, Long span of geologic time. In formal usage, eons are the longest portions of geologic time (era s are the second-longest). 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.
3. Geological time scale - Digital Atlas of Ancient Life
网页Eons. The eon is the broadest category of geological time. Earth's history is characterized by four eons; in order from oldest to youngest, these are the Hadeon, Archean, Proterozoic, and Phanerozoic. Collectively, the Hadean, Archean, and Proterozoic are sometimes informally referred to as the "Precambrian."
Eon - Simple English Wikipedia, the free encyclopedia
网页An eon (or aeon) is a term in Earth science for the longest periods of time. It describes a part of the Earth 's existence lasting hundreds of millions to billions of years. A geologic eon is part of Earth's existence, made up of a number of eras of different lengths.
The 2015 Geologic Time Scale: Eons and Eras - ThoughtCo
网页2020年3月18日 · This table shows the highest-level units of the geologic time scale: eons and eras. Where available, the names link to more detailed descriptions or significant events that occurred during that specific eon or era.
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