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This is a list of such named time periods as defined in various fields of study. These can be divided broadly into prehistorical periods and historical periods (when written records began to be kept).
This work assessed the geologic history of the currently defined eons and eras of the pre-Cambrian, [note 2] and the proposals in the "Geological Time Scale" books 2004, [74] 2012, [5] and 2020. [75] Their recommend revisions [ 4 ] of the pre-Cryogenian geologic time scale were (changes from the current scale [v2023/09] are italicised):
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 ...
The ages of more recent layers are calculated primarily by the study of fossils, which are remains of ancient life preserved in the rock. These occur consistently and so a theory is feasible. Most of the boundaries in recent geologic time coincide with extinctions (e.g., the dinosaurs) and with the appearances of new species (e.g., hominids).
The Paleozoic era spanned roughly (Ma) [39] and is subdivided into six geologic periods: from oldest to youngest, they are the Cambrian, Ordovician, Silurian, Devonian, Carboniferous and Permian. Geologically, the Paleozoic starts shortly after the breakup of a supercontinent called Pannotia and at the end of a global ice age.
Chronostratigraphy is the branch of stratigraphy that studies the ages of rock strata in relation to time. The ultimate aim of chronostratigraphy is to arrange the sequence of deposition and the time of deposition of all rocks within a geological region, and eventually, the entire geologic record of the Earth .
Pages in category "Geological eras" The following 12 pages are in this category, out of 12 total. This list may not reflect recent changes. . Erathem; C. Cenozoic;
For earlier time periods, see Timeline of the Big Bang, Geologic time scale, Timeline of evolution, and Logarithmic timeline This page was last edited on 29 ...