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Early Earth also known as proto-earth is loosely defined as encompassing Earth in its first one billion years, or gigayear (Ga, 10 9 y), [1] from its initial formation in the young Solar System at about 4.55 Ga to some time in the Archean eon in approximately 3.5 Ga. [2] On the geologic time scale, this comprises all of the Hadean eon, starting ...
Earth formed around 4.54 billion years ago, approximately one-third the age of the universe, by accretion from the solar nebula. [4] [5] [6] Volcanic outgassing probably created the primordial atmosphere and then the ocean, but the early atmosphere contained almost no oxygen. Much of the Earth was molten because of frequent collisions with ...
In 1862, the physicist William Thomson, 1st Baron Kelvin published calculations that fixed the age of Earth at between 20 million and 400 million years. [19] [20] He assumed that Earth had formed as a completely molten object, and determined the amount of time it would take for the near-surface temperature gradient to decrease to its present value.
The Earth of the early Archean may have had a different tectonic style. It is widely believed that the early Earth was dominated by vertical tectonic processes, such as stagnant lid , [ 19 ] [ 20 ] heat-pipe , [ 21 ] or sagduction , [ 22 ] [ 23 ] [ 24 ] which eventually transitioned to plate tectonics during the planet's mid-stage evolution.
The Hadean (/ h eɪ ˈ d iː ə n, ˈ h eɪ d i ə n / hay-DEE-ən, HAY-dee-ən) is the first and oldest of the four known geologic eons of Earth's history, starting with the planet's formation about 4.6 billion years ago [4] [5] (estimated 4567.30 ± 0.16 million years ago [2] set by the age of the oldest solid material in the Solar System — protoplanetary disk dust particles — found as ...
Historically, "Earth" has been written in lowercase. Beginning with the use of Early Middle English, its definite sense as "the globe" was expressed as "the earth". By the era of Early Modern English, capitalization of nouns began to prevail, and the earth was also written the Earth, particularly when referenced along with other heavenly bodies.
The age of Earth is about 4.54 billion years; [7] [33] [34] the earliest undisputed evidence of life on Earth dates from at least 3.5 billion years ago according to the stromatolite record. [35] Some computer models suggest life began as early as 4.5 billion years ago. [36] [37] The oldest evidence of life is indirect in the form of isotopic ...
The earliest Earth crust probably forms similarly out of similar material. On Earth the pluvial period starts, in which the Earth's crust cools enough to let oceans form. c. 4,404 Ma – First known mineral, found at Jack Hills in Western Australia. Detrital zircons show presence of a solid crust and liquid water.