archean eon
the Hadean eon
Hadean, Archeozoic, Proterozoic, Phanerozoic
The Hadean Eon, the earliest time interval, was when the Earth was cooling, and continents and oceans formed. Lifeforms are thought to have appeared in the following eon, the Archean Eon.(eras are a much smaller time interval, and the Hadean is not normally subdivided into these)
It was drastically different that what it is today. In fact, that might be an understatement. First, consider, the name Hadean. It is derived from the word "Hades" which means hell or underworld. The Earth at that time was literally hellish. It was hot to the point where oceans could not exist, noxious gases spewed out by volcanoes suffocated the atmosphere, thick clouds made of poisonous vapors enveloped the Earth, and the surface was made of molten lava or scorched rubble. Eventually, though, the Earth would cool down, and that would bring us into the Archean Eon.
archean eon
the Hadean eon
"The Hadean time period is often referred to as the 'Hadean Eon.'"
Hadean, Archeozoic, Proterozoic, Phanerozoic
The Hadean Eon, the earliest time interval, was when the Earth was cooling, and continents and oceans formed. Lifeforms are thought to have appeared in the following eon, the Archean Eon.(eras are a much smaller time interval, and the Hadean is not normally subdivided into these)
Precambrian is an informal term for the time before the Cambrian Period, the first period of the Phanerozoic Eon. The Precambrian consists of three eons, the Hadean, the Archean, and the Proterozoic. The Hadean Eon is about 760,000,000 years long. The Archean Eon is about 1,300,000,000 years long. The Proterozoic Eon is about 1,960,000,000 years long This comes to a total of 4,025,000,000 years.
The oldest eon of geologic time is the Archaean Eon of the Precambrian period. The oldest rocks and fossils date from this time, about 3.8 to 2.5 billion years ago. (Prior to that, the Hadean Eon began with the formation of the Earth. No geologic record exists from the Hadean, during which the Earth cooled from its molten state.)
The Hadean Eon covers the time from accretion to the earliest known rocks.
The Hadean Eon lasted from Earths formation about 4.5762 billion years ago until 4 billion years ago, some 576.2 million years.
It was drastically different that what it is today. In fact, that might be an understatement. First, consider, the name Hadean. It is derived from the word "Hades" which means hell or underworld. The Earth at that time was literally hellish. It was hot to the point where oceans could not exist, noxious gases spewed out by volcanoes suffocated the atmosphere, thick clouds made of poisonous vapors enveloped the Earth, and the surface was made of molten lava or scorched rubble. Eventually, though, the Earth would cool down, and that would bring us into the Archean Eon.
It started about 4.6 billion years ago, and ended about 3.8 billion years ago.
An eon is a made up of two or more eras. They are defined in terms of what was happening on the planet in biological and geological terms rather than in number of years. We are now 541 million yeras (Myr) into the current eon - the Phanerozoic eon. Before that was the Proterozoic eon which lasted 1959 Myr, the Archean eon (1500 Myr) and the oldest, the Hadean eon (500 Myr).