Geologic Time

地质时期

　

(1) English Version

(2) Chinese Version

　

(1)


Geologic Time
 
 
Eon
 		 Era Period Epoch (and sub-epoch*) ~million yrs ago
Phanerozoic Cenozoic Quaternary Holocene 0.01**
Pleistocene 1.6
Tertiary Neogene Pliocene Late/Early 3.4/5.3
Miocene Late/Middle/Early 11.2/16.6/23.7
Paleogene Oligocene Late/Early 30/36.6
Eocene Late/Middle/Early 43.6/52/57.8
Paleocene Late/Early 63.6/66.4
Mesozoic Cretaceous Late/Early 97.5/144
Jurassic Late/Middle/Early 163/187/208
Triassic Late/Middle/Early 230/240/245
Paleozoic Permain Late/Early 258/286
Carboniferous Late(Pennsylvanian)/Early(Mississippian) 320/360
Devonian Late/Middle/Early 374/387/408
Silurian Late/Early 421/438
Ordovician Late/Middle/Early 458/478/505
Cambrain Late/Middle/Early 523/540/570
Prephanerozoic Proterozoic Late/Middle/Early (Note: Precambrain time) 900/1600/2500
Archean Late/Middle/Early (Note: Precambrain time) 3000/3400/3960
Hadean 　 　 3900-4500
Geologic time, the extensive interval of time occupied by the Earth's geologic history. It extends from about 3.9 billion years ago (corresponding to the age of the oldest known rocks) to the present day. It is, in effect, that segment of Earth history that is represented by and recorded in rock strata.
The geologic time scale is the "calendar" for events in Earth history. It subdivides all time since the end of the Earth's formative period as a planet (nearly 4 billion years ago) into named units of abstract time: the latter, in descending order of duration, are eons, eras, periods, and epochs. The enumeration of these geologic time units is based on stratigraphy which is the correlation and classification of rock strata. The fossil forms that occur in these rocks provide the chief means of establishing a geologic time scale. Because living things have undergone evolutionary changes over geologic time, particular kinds of organisms are characteristic of particular parts of the geologic record. By correlating the strata in which certain types of fossils are found, the geologic history of various regions (and of the Earth as a whole) can be reconstructed. The relative geologic time scale developed from the fossil record has been numerically quantified by means of absolute dates obtained with radiometric dating methods.

* : For Tertiary time only       ** : i.e., the last 10,000 years

Note: ~ = approximately,  yrs = years   //   Ref: <Encyclopaedia Britannica> (1994)

Note: Prephanerozoic & Hadean are added portion copied from Ref: <Microcosmos> (by L. Margulis & D. Sagan)

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(2)


地质时期
 
 
宙
 		 代 纪 世(及亚世*) ~距今(百万年)
显生宙 新生代 第四纪 全新 0.01**
更新 1.6
第三纪 新第三纪 上新 晚/早 3.4/5.3
中新 晚/中/早 11.2/16.6/23.7
老第三纪 渐新 晚/早 30/36.6
始新 晚/中/早 43.6/52/57.8
古新 晚/早 63.6/66.4
中生代 白垩纪 晚/早 97.5/144
侏罗纪 晚/中/早 163/187/208
三叠纪 晚/中/早 230/240/245
古生代 二叠纪 晚/早 258/286
石炭纪 晚(宾夕法尼亚)/早(密西西比) 320/360
泥盆纪 晚/中/早 374/387/408
志留纪 晚/早 421/438
奥陶纪 晚/中/早 458/478/505
寒武纪 晚/中/早 523/540/570
隐生宙 元古宙 晚/中/早 (注：前寒武纪时期) 900/1600/2500
太古宙 晚/中/早 (注：前寒武纪时期) 3000/3400/3960
超古宙 　 　 3900-4500
地质时期，为地球的地质历史所占据的漫长的时间范围， 从大约39亿年前(相当于已知最老岩石的年龄)延续到今天，实际上就是由地层所代表并记录在地层中的那一段地球的历史。
地质年表就是关于地球历史上重大事件的“历书”。 该表把地球形成行星的阶段结束(将近40亿年前)以来的全部时间，划分为定了名的抽象时间的单位： 按延续时间递减的顺序，依次是宙、代、纪、世。 对这些地质时间单元的排序，依据的是地层学，这就是对地层的对比和划分。出现在这些地层中的生物化石为建立一张地质年表提供了主要手段。 因为活的生物在地质时间范围内经历过演变进化，所以特定的生物种类是地质记录的特定部分所特有的。 通过对存在某些化石种类的地层的对比，就能把各个不同区域(以及整个地球)的地质历史恢复原貌。根据化石记录拟定的相对地质年表，已经用放射性年龄测定法所取得的绝对年代，进行了数值定量。

*: 只用于第三纪       **: 即最近 10,000 年

注: ~ = 近似     //    参考: <不列颠百科全书>(1999)

注：隐生宙及超古宙是增添部份。参考：<演化之舞> (by Lynn Margulis & Dorion Sagan)

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