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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 · The most recent geologic eon is the Phanerozoic, which began about 540 million years ago. This eon is very distinct from the previous three—the Hadean, Archean, and Proterozoic—which are sometimes known as the Precambrian era. During the Cambrian period—the earliest part of the Phanerozoic—the first complex organisms appeared.
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.
18 mar 2020 · The periods of the three Phanerozoic eras are divided in turn into epochs. (See the Phanerozoic epochs listed together.) Epochs are subdivided into ages. Because there are so many ages, they are presented separately for the Paleozoic Era, the Mesozoic Era and the Cenozoic Era.
Keep your geochronological dates straight with Wolfram|Alpha's detailed information on Earth's geologic time scale. Drill down from the eons through the epochs and analyze data on the climate changes, impacts, extinctions and continental shifts that formed the unique geology of each time division.
