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13 wrz 2024 · The geologic time scale is the “calendar” for events in Earth history. It subdivides all time into named units of abstract time called—in descending order of duration— eons, eras, periods, epochs, and ages.
- EONS
Eon, Long span of geologic time. In formal usage, eons are...
- Lipalian Interval
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- Periods
period, in geology, the basic unit of the geologic time...
- Era
Era, a very long span of geological time; in formal usage,...
- Epochs
epoch, unit of geological time during which a rock series is...
- Name That Geologic Interval
Forests and the coiled-shell-bearing marine organisms known...
- Geologic Time
Geologic time is the billions of years since the planet...
- EONS
An eon is the largest geochronologic time unit and is equivalent to a chronostratigraphic eonothem. [13] There are four formally defined eons: the Hadean, Archean, Proterozoic and Phanerozoic. [2] An era is the second largest geochronologic time unit and is equivalent to a chronostratigraphic erathem.
28 lut 2020 · Geologic time spans are divided into units and subunits, the largest of which are eons. Eons are divided into eras, which are further divided into periods, epochs, and ages. Geologic dating is extremely imprecise.
The great Precambrian expanse of time is divided into the Proterozoic, Archean, and Hadean eons in order of increasing age. The names of the eras in the Phanerozoic eon (the eon of visible life) are the Cenozoic ("recent life"), Mesozoic ("middle life") and Paleozoic ("ancient life").
A major task for the world stratigraphical community has been to establish a single, universal scheme for the subdivision of geological time. There is agreement at the levels of eon, era and (for the most part) period, but regional terms continue to be widely used at the lower hierarchical levels.
Figure 12.1 shows you what the geologic time scale looks like. We now live in the Phanerozoic eon, the Cenozoic era, and the Quarternary period. Sometimes, periods are further divided into epochs, but they are usually just named “early” or “late”, for example, “late Jurassic”, or “early Cretaceous”.
1 sty 2018 · The appearance, absence, acme, or coexistence of fossil organisms is variously used to construct a hierarchy of units, in the following order of increasing stratigraphic resolution: eonothem, erathem, system, series, and stage. The parallel geochronologic units are the eon, era, period, epoch, and age.
