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  2. List of time periods - Wikipedia

    en.wikipedia.org/wiki/List_of_time_periods

    Homininaeid EraPeriod prior to the existence of Homininae Homininid EraPeriod prior to the existence of Hominini Prehistory – Period between the appearance of Homo ("humans"; first stone tools c. three million years ago) and the invention of writing systems (for the Ancient Near East : c. five thousand years ago).

  3. Geologic time scale - Wikipedia

    en.wikipedia.org/wiki/Geologic_time_scale

    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 ...

  4. Era - Wikipedia

    en.wikipedia.org/wiki/Era

    An era is a span of time defined for the purposes of chronology or historiography, as in the regnal eras in the history of a given monarchy, a calendar era used for a given calendar, or the geological eras defined for the history of Earth. [1] Comparable terms are epoch, age, period, saeculum, aeon (Greek aion) [2] and Sanskrit yuga. [3]

  5. Geological history of Earth - Wikipedia

    en.wikipedia.org/wiki/Geological_history_of_Earth

    The Paleogene (alternatively Palaeogene) Period is a unit of geologic time that began 66 and ended 23.03 Ma [10] and comprises the first part of the Cenozoic Era. This period consists of the Paleocene, Eocene and Oligocene Epochs.

  6. Category:Historical eras - Wikipedia

    en.wikipedia.org/wiki/Category:Historical_eras

    This category's scope is limited to human-related history since the end of Earth's most recent glacial period ("the Ice Age") around 10,000 to 15,000 years ago. History portal; See also. List of time periods, which includes periods used in fields such as palaeogeography, palaeoecology, archaeology and cosmology.

  7. List of geochronologic names - Wikipedia

    en.wikipedia.org/wiki/List_of_geochronologic_names

    period Mesozoic ICS Crete; Latin creta=chalk: d'Omalius d'Halloy, 1822 Croixan: epoch Cambrian North America Cromerian: 0.85 0.465 super-age/age Pleistocene Netherlands, Great Britain Cromer (England) Reid, 1882 Cryogenian: 850 635.5 ± 1.2 [7] period Proterozoic ICS frozen beginning: Plumb, 1991 Cryptic: 4,567 4,150 epoch Prenectarian Moon ...

  8. Timeline of the early universe - Wikipedia

    en.wikipedia.org/wiki/Timeline_of_the_early_universe

    c. 10 −43 seconds: Grand unification epoch begins: While still at an infinitesimal size, the universe cools down to 10 32 kelvin. Gravity separates and begins operating on the universe—the remaining fundamental forces stabilize into the electronuclear force, also known as the Grand Unified Force or Grand Unified Theory (GUT), mediated by (the hypothetical) X and Y bosons which allow early ...

  9. Epoch - Wikipedia

    en.wikipedia.org/wiki/Epoch

    A common astronomical epoch is J2000, which is noon on January 1, 2000, Terrestrial Time. An epoch in Geochronology is a period of time, typically in the order of tens of millions of years. The current epoch is the Holocene.