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These units are arranged in a hierarchy: eon, era, period, epoch, subepoch, age, and subage. [14] Geochronology is the scientific branch of geology that aims to determine the age of rocks, fossils, and sediments either through absolute (e.g., radiometric dating) or relative means (e.g., stratigraphic position, paleomagnetism, stable isotope ...
On the geologic time scale, the Holocene epoch starts at the end of the last glacial period of the current ice age (c. 10,000 BC) and continues to the present. The beginning of the Mesolithic is usually considered to correspond to the beginning of the Holocene epoch.
An epoch in astronomy is a reference time used for consistency in calculation of positions and orbits. A common astronomical epoch is J2000, which is noon on January 1, 2000, Terrestrial Time. An epoch in Geochronology is a time period, typically in the order of tens of millions of years. The current epoch is the Holocene.
c. 23.04 Ma – Neogene Period and Miocene epoch begin; c. 22 Ma – First hyenas. c. 20 Ma – Giraffes and giant anteaters evolve. c. 18–12 Ma – estimated age of the Hominidae/Hylobatidae (great apes vs. gibbons) split. c. 16 Ma – The hippopotamus evolves. c. 15 Ma – First mastodons, bovids, and kangaroos. Australian megafauna diversify.
The Pleistocene (/ ˈ p l aɪ s t ə ˌ s iː n,-s t oʊ-/ PLY-stə-seen, -stoh-; [4] [5] referred to colloquially as the Ice Age) is the geological epoch that lasted from c. 2.58 million to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations.
Period: 22 defined, tens to ~one hundred million years Series: Epoch: 34 defined, tens of millions of years Stage: Age: 99 defined, millions of years Chronozone: Chron: subdivision of an age, not used by the ICS timescale
Series is a term defining a unit of rock layers formed during a certain interval of time (a chronostratigraphic unit); it is equivalent (but not synonymous) to the term geological epoch (see epoch criteria) which defines the interval of time itself, although the two words are sometimes confused in informal literature.
age Proterozoic Siberia Aksayan: 493 491.5 age Cambrian Russia, Kazakhstan Ergaliev, 1980 Alaunian: 216 211 sub-age Triassic Europe Albertan: epoch Cambrian North America Dawson, 1895 Albian: 112.0 ± 1.0 99.6 ± 0.9 age Cretaceous ICS Albia, Latin name of the river Aube (France) d'Orbigny, 1842 Alding(i)an: 36 30 age Eocene Australia Algonkian ...