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:
“A two-year-old can be taught to curb his aggressions completely if the parents employ strong enough methods, but the achievement of such control at an early age may be bought at a price which few parents today would be willing to pay. The slow education for control demands much more parental time and patience at the beginning, but the child who learns control in this way will be the child who acquires healthy self-discipline later.”
—Selma H. Fraiberg (20th century)
“Of all things upon earth that bleed and grow,
A herb most bruised is woman.”
—Euripides (c. 480–406 B.C.)