Search results
Results from the WOW.Com Content Network
Homininaeid Era – Period prior to the existence of Homininae Homininid Era – Period 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).
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 ...
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]
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.
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.
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 ...
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 ...
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.