- the succession of eras, periods, and epochs as considered in historical geology.[1860-65]
* * *Interval of time occupied by the Earth's geologic history, extending from с 3.9 billion years ago (corresponding to the age of the oldest known rocks) to the present day. It is, in effect, the part of the Earth's history that is recorded in rock strata. The geologic time scale is classified in nested intervals distinguished by characteristic geologic and biologic features. From longest to shortest duration, the intervals are eon, era, period, and epoch.
* * *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. See also geochronology.
* * *
Look at other dictionaries:
geologic time — or geological time n. the time period (c. 4.55 billion years) representing the earth s geologic history: see the geologic time chart in the Reference Supplement … English World dictionary
geologic time — noun Date: 1861 the long period of time occupied by the earth s geologic history … New Collegiate Dictionary
geologic time — noun the time of the physical formation and development of the earth (especially prior to human history) • Syn: ↑geological time • Hypernyms: ↑time • Hyponyms: ↑eon, ↑aeon, ↑period, ↑ … Useful english dictionary
geologic time — The total time involved since formation of the earth to the present time … Geography glossary
geologic time — ge′olog′ic time′ n. gel the succession of eras, periods, and epochs as considered in historical geology • Etymology: 1860–65 … From formal English to slang
Geologic time scale — This clock representation shows some of the major units of geological time and definitive events of Earth history. The Hadean eon represents the time before fossil record of life on Earth; its upper boundary is now regarded as 4.0 Ga. Other… … Wikipedia
geologic time scale — geologinio laiko skalė statusas T sritis Standartizacija ir metrologija apibrėžtis Sąlyginė chronologinė geologinių įvykių seka, vartojama kaip tam tikro geologinio periodo matas. atitikmenys: angl. geologic time scale rus. шкала геологического… … Penkiakalbis aiškinamasis metrologijos terminų žodynas
geologic time scale — see http://www.geosociety.org/science/timescale/timescl.htm … Geography glossary
New Zealand geologic time scale — While also using the international Geologic time scale, many nations especially those with isolated and therefore non standard prehistories use their own system of dividing geologic time into epochs and faunal stages. In New Zealand, these epochs … Wikipedia
Time from NPL — Map showing the location of the Anthorn VLF transmitter within Cumbria … Wikipedia