https://zh.wikipedia.org/wiki/%E5%9C%B0%E8%B4%A8%E5%B9%B4%E4%BB%A3
| 年代地層學 岩段（地層） | 地質年代學 時間間隔 | 說明 |
|---|---|---|
| 共有4個，大於5億年 | ||
| 共有14個，數億年 | ||
| 共有22個，數千萬至數億年 | ||
| 共有34個，數千萬年 | ||
| 共有99個，數百萬年 | ||
| 小於期，國際地層委員會（ICS）不使用 | ||
https://en.wikipedia.org/wiki/Geologic_time_scale#Terminology
Divisions of geologic time
- An eon （宙）is the largest geochronologic time unit and is equivalent to a chronostratigraphic eonothem.[12] There are four formally defined eons: the Hadean, Archean, Proterozoic and Phanerozoic.[2]
- An era （代） is the second largest geochronologic time unit and is equivalent to a chronostratigraphic erathem.[7][12] There are ten defined eras: the Eoarchean, Paleoarchean, Mesoarchean, Neoarchean, Paleoproterozoic, Mesoproterozoic, Neoproterozoic, Paleozoic, Mesozoic and Cenozoic, with none from the Hadean eon.[2]
- A period （紀）is equivalent to a chronostratigraphic system.[7][12] There are 22 defined periods, with the current being the Quaternaryperiod.[2] As an exception two subperiods are used for the Carboniferous Period.[7]
- An epoch （世）is the second smallest geochronologic unit. It is equivalent to a chronostratigraphic series.[7][12] There are 37 defined epochs and one informal one. There are also 11 subepochs which are all within the Neogene and Quaternary.[2] The use of subepochs as formal units in international chronostratigraphy was ratified in 2022.[13]
- An age （期）is the smallest hierarchical geochronologic unit and is equivalent to a chronostratigraphic stage.[7][12] There are 96 formal and five informal ages.[2]
- A chron is a non-hierarchical formal geochronology unit of unspecified rank and is equivalent to a chronostratigraphic chronozone.[7] These correlate with magnetostratigraphic, lithostratigraphic, or biostratigraphic units as they are based on previously defined stratigraphic units or geologic features.
如果把地球誕生到現在的大約45億年縮小到1年，則人類（Homo sapiens）存在的時間只有極短的半個小時。
意思是說，森羅萬象的物種的出現（寒武紀大爆發，五億四千萬年前）是意外，人類的發生（中新世 （Miocene）末期，六百萬年前），則當然是，意外的意外，
