The answer is debated amongst geologists, astrologists and palaeontologists - the earliest period in life's history is the Archean eon, when the first proto-cells were thought to have formed. The earliest period there, is the Eoarchean - 4200 - 4400 million years ago. However, the earliest eon is the Hadean, which encompasses the formation of the Earth as celestial body 4600 million years ago, up to 4200 million years ago. The earth was formed by accretion (gravitational attraction of smaller bodies, to form a central object of greater mass, thus attracting more smaller bodies, and so on), within 10 - 20 million years, so, other than describing this period of Earth's history as 'Proto-Earth', there isn't really a way of classifying even earlier stages, unless you are willing to look into the stages of accretion in forming planets. (The earliest stage would probably be a 'proto-planetary disk' stage, which was itself formed as a by-product of the formation of the sun, followed by a kilometre-wide planetisimal, and then a Mars sized 'embryo', growing progressively. In this sense, the Earth and the Sun are descended from the same Giant Molecular Cloud, or GMC.)
The period of Earth's history that lasted 245 to 208 million years ago is the Triassic period. This period followed the Permian period and preceded the Jurassic period. It was a time of recovery and diversification of life after the mass extinction at the end of the Permian period.
The Hettangian Epoch. The liassic epoch.
The Vendian Period, also known as the Ediacaran Period, was the final geologic period of the Neoproterozoic Era before the Cambrian Period. It lasted from about 635 million to 541 million years ago and is known for the appearance of complex multicellular life forms, including the earliest known animals.
Nitrogen has made up the largest portion of Earth's atmosphere for most of Earth's history. It currently makes up about 78% of the atmosphere.
The measurement of Earth's history divided into time periods is called the geological time scale. It is divided into eons, eras, periods, epochs, and ages, with each unit representing a significant change in Earth's geological and biological history.
The first period of human life is called pre-history
John William Abbott has written: 'A history of London, from the earliest period to the present time' -- subject(s): History 'A history of London from the earliest period'
The Devonian Period was from 416 MYA - 360 MYA.
precambrian era
The Precambrian time
The Precambrian Time
unicellular organisms are earliest forms of life
John Goding has written: 'A history of Cheltenham from the earliest period'
fossil record geologic time scale
W. Knighton has written: 'The history of Ceylon from the earliest period to the present time' -- subject(s): History
golden age
1. old stone age 2. paleolithic age