Early Earth is a term usually defined as Earth's first billion years, or gigayear. On the geologic time scale, this comprises all of the Hadean eon (itself unofficially defined), as well as the Eoarchean and part of the Paleoarchean eras of the Archean eon.
This period of Earth's history, being its earliest, involved the planet's condensation from a solar nebula and accretion from meteorites, as well as the formation of the earliest atmosphere and hydrosphere. It was also defined by the emergence of life and, later, photosynthesis. The earliest supracrustals (such as the Isua greenstone belt) date from the latter half of this period, about 3.8 gya, around the same time as peak late heavy bombardment.
Famous quotes containing the words early and/or earth:
“In the early days of the world, the Almighty said to the first of our race “In the sweat of thy face shalt thou eat bread”; and since then, if we except the light and the air of heaven, no good thing has been, or can be enjoyed by us, without having first cost labour.”
—Abraham Lincoln (1809–1865)
“Illiterate him, I say, quite from your memory.... There is nothing on earth so easy as to forget, if a person chooses to set about it. I’m sure I have as much forgot your poor, dear uncle, as if he had never existed—and I thought it my duty to do so.”
—Richard Brinsley Sheridan (1751–1816)