Search results
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.
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.
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.
18 mar 2020 · This table shows the highest-level units of the geologic time scale: eons and eras. Where available, the names link to more detailed descriptions or significant events that occurred during that specific eon or era.
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").
Eras. Eons of geological time are subdivided into eras, which are the second-longest units of geological time. The Phanerozoic eon is divided into three eras: the Paleozoic, Mesozoic, and Cenozoic.
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.
