The Precambrian is divided into three eons: the Hadean (4567–4031 Ma), Archean (4031-2500 Ma) and Proterozoic (2500-538.8 Ma). See Timetable of the Precambrian. Proterozoic: this eon refers to the time from the lower Cambrian boundary, 538.8 Ma, back through 2500 Ma.

The geologic time scale is divided into chronostratigraphic units and their corresponding geochronologic units. 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]

Eons. The eon is the broadest category of geological time. Earth's history is characterized by four eons; in order from oldest to youngest, these are the Hadeon, Archean, Proterozoic, and Phanerozoic. Collectively, the Hadean, Archean, and Proterozoic are sometimes informally referred to as the "Precambrian."

Each eon, era, period, and epoch is defined by major geological or paleontological events. The eons are the Hadean, Archean, Proterozoic, and Phanerozoic. The Phanerozoic Eon is the eon of visible life, and is divided into three eras: the Paleozoic, Mesozoic, and Cenozoic.

Eon, Long span of geologic time. In formal usage, eons are the longest portions of geologic time (eras are the second-longest). Three eons are recognized: the Phanerozoic Eon (dating from the present back to the beginning of the Cambrian Period), the …

Feb 28, 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.

Dec 6, 2023 · The third eon, the Proterozoic, lasted from 2.5 billion to 541 million years ago. This was a time of the evolution of early life forms and the formation of the first continents.

Jan 11, 2025 · The four eons are the Hadean, Archean, Proterozoic, and Phanerozoic. The Hadean era lasted around 600 million years and includes the formation of the Earth and Moon. The Archean era lasted around 1.5 billion years, encompassing the formation of the crust and the first stirrings of life.

An Eon is the longest division of geologic time, so long in fact that there have only been four Eons. Collectively the first three eons are called the Precambrian, that stretch of geological time from the formation of the Earth itself to the start of the Cambrian period.

Dec 16, 2024 · The primarily defined divisions of time are eons, the Hadean, the Archean, the Proterozoic and the Phanerozoic. The first three of these can be referred to collectively as the Precambrian supereon. Each eon is subsequently divided into eras, which in turn are divided into periods, which are further divided into epochs.