Hadean ( /ˈheɪdiən/) is a geologic eon of the
the Archean. It began with the formation of the
Earth about 4.6
billion years ago and ended, as defined by the ICS, 4 billion years
ago. As of 2016[update], the ICS describes its status as
informal. The geologist
Preston Cloud coined the term in 1972,
originally to label the period before the earliest-known rocks on
W. Brian Harland later coined an almost synonymous term: the
"Priscoan period". Other, older texts simply refer to the eon as the
Artist's impression of a
4 Atmosphere and oceans
5 See also
7 Further reading
8 External links
view • discuss • edit
Earliest sexual reproduction
Axis scale: million years
Orange labels: ice ages.
Human timeline and Nature timeline
"Hadean" (from Hades, the Greek god of the underworld) describes the
hellish conditions then prevailing on Earth: the planet had just
formed and was still very hot owing to its recent accretion, the
abundance of short-lived radioactive elements, and frequent collisions
with other Solar System bodies.
Since few geological traces of this eon remain on Earth, there is no
official subdivision. However, the
Lunar geologic timescale
Lunar geologic timescale embraces
several major divisions relating to the Hadean, so these are sometimes
used in an informal sense to refer to the same periods of time on
The Lunar divisions are:
Pre-Nectarian, from the formation of the Moon's crust
(4,533 million years ago) up to about 3,920 million years
Nectarian ranging from 3,920 million years ago up to about
3,850 million years ago, in a time when the Late Heavy
Bombardment, according to that theory, was in a stage of decline.
In 2010, an alternative scale was proposed that includes the addition
of the Chaotian and Prenephelean Eons preceding the Hadean, and
Hadean into three eras with two periods each. The
Paleohadean era consists of the Hephaestean (4.5-4.4 Ga) and the
Jacobian periods (4.4-4.3 Ga). The Mesohadean is divided into the
Canadian (4.3-4.2 Ga) and the Procrustean periods (4.2-4.1 Ga). The
Neohadean is divided into the Acastan (4.1-4.0 Ga) and the Promethean
periods (4.0-3.9 Ga). As of February 2017[update], this has
not been adopted by the IUGS.
Further information: Oldest dated rocks
In the last decades of the 20th century geologists identified a few
Hadean rocks from Western Greenland, Northwestern Canada, and Western
Australia. In 2015, traces of carbon minerals interpreted as "remains
of biotic life" were found in 4.1-billion-year-old rocks in Western
The oldest dated zircon crystals, enclosed in a metamorphosed
sandstone conglomerate in the
Jack Hills of the Narryer Gneiss Terrane
of Western Australia, date to 4.404 ± 0.008 Ga. This zircon is a
slight outlier, with the oldest consistently-dated zircon falling
closer to 4.35 Ga—around 200 million years after the hypothesized
time of the Earth's formation.
In many other areas xenocryst, or relict
Hadean zircons enclosed in
older rocks indicate that younger rocks have formed on older terranes
and have incorporated some of the older material. One example occurs
in the Guiana shield from the Iwokrama Formation of southern Guyana
where zircon cores have been dated at 4.22GA.
Atmosphere and oceans
A sizeable quantity of water would have been in the material that
formed the Earth.
Water molecules would have escaped Earth's
gravity more easily when it was less massive during its formation.
Hydrogen and helium are expected to continually escape (even to the
present day) due to atmospheric escape. Part of the ancient planet is
theorized to have been disrupted by the impact that created the Moon,
which should have caused melting of one or two large regions of the
Earth. Earth's present composition suggests that there was not
complete remelting as it is difficult to completely melt and mix huge
rock masses. However, a fair fraction of material should have been
vaporized by this impact, creating a rock vapor atmosphere around the
young planet. The rock vapor would have condensed within two thousand
years, leaving behind hot volatiles which probably resulted in a heavy
2 atmosphere with hydrogen and water vapor. Liquid water oceans
existed despite the surface temperature of 230 °C (446 °F)
because at an atmospheric pressure of above 27 atmospheres, caused by
the heavy CO
2 atmosphere, water is still liquid. As cooling continued, subduction
and dissolving in ocean water removed most CO
2 from the atmosphere but levels oscillated wildly as new surface and
mantle cycles appeared.
Studies of zircons have found that liquid water must have existed as
long ago as 4.4 billion years ago, very soon after the formation of
the Earth. This requires the presence of an atmosphere.
The Cool Early
Earth theory covers a range from about 4.4–4.0
A September 2008 study of zircons found that Australian
holds minerals pointing to the existence of plate tectonics as early
as 4 billion years. If this is true, the time when Earth
finished its transition from having a hot, molten surface and
atmosphere full of carbon dioxide, to being very much like it is
today, can be roughly dated to about 4.0 billion years ago. The
actions of plate tectonics and the oceans trapped vast amounts of
carbon dioxide, thereby eliminating the greenhouse effect and leading
to a much cooler surface temperature and the formation of solid rock,
and possibly even life.
Formation and evolution of the Solar System
History of Earth – the first sections describe the formation of
Oldest dated rocks
Timeline of natural history
^ "International Chronostratigraphic Chart 2015" (PDF). ICS. Retrieved
23 January 2016.
^ Ogg, J.G.; Ogg, G.; Gradstein, F.M. (2016). A Concise Geologic Time
Scale: 2016. Elsevier. p. 20. ISBN 978-0-444-63771-0.
^ "The Eons of Chaos and Hades" (PDF). Solid Earth. January 26,
^ Borenstein, Seth (19 October 2015). "Hints of life on what was
thought to be desolate early Earth". Excite. Yonkers, NY: Mindspark
Interactive Network. Associated Press. Retrieved 2015-10-20.
^ Bell, Elizabeth A.; Boehnike, Patrick; Harrison, T. Mark; et al. (19
October 2015). "Potentially biogenic carbon preserved in a 4.1
billion-year-old zircon" (PDF). Proc. Natl. Acad. Sci. U.S.A.
Washington, D.C.: National Academy of Sciences. 112: 14518–21.
ISSN 1091-6490. PMC 4664351 . PMID 26483481.
Retrieved 2015-10-20. Early edition, published online before
^ a b Wilde, Simon A.; Valley, John W.; Peck, William H.; Graham,
Colin M. (2001). "Evidence from detrital zircons for the existence of
continental crust and oceans on the
Earth 4.4 Gyr ago". Nature. 409
(6817): 175–178. doi:10.1038/35051550.
^ Nadeau, Serge; Chen, Wei; Reece, Jimmy; Lachhman, Deokumar; Ault,
Randy; Faraco, Maria; Fraga, Leda; Reis, Nelson; Betiollo, Leandro
(2013-12-01). "Guyana: the Lost
Hadean crust of South America?".
Brazilian Journal of Geology. 43: 601–606.
^ Drake, Michael J. (2005), "Origin of water in the terrestrial
planets" (PDF), Meteoritics & Planetary Science, 40 (4):
doi:10.1111/j.1945-5100.2005.tb00958.x, archived from the original
(PDF) on 2011-10-09 .
^ Solar System Exploration: Science & Technology: Science
Features: View Feature
^ Sleep, N. H.; Zahnle, K.; Neuhoff, P. S. (2001), "Initiation of
clement surface conditions on the earliest Earth", PNAS, 98 (7):
3666–3672, Bibcode:2001PNAS...98.3666S, doi:10.1073/pnas.071045698,
PMC 31109 , PMID 11259665 .
^ ANU - Research School of
Earth Sciences - ANU College of Science -
Harrison Archived 2006-06-21 at Archive.is
^ ANU - OVC - MEDIA - MEDIA RELEASES - 2005 - NOVEMBER -
^ A Cool Early Earth
^ a b Chang, Kenneth (December 2, 2008). "A New Picture of the Early
Earth". The New York Times.
^ a b Abramov, Oleg; Mojzsis, Stephen J. (December 2008). "Thermal
State of the Lithosphere During Late Heavy Bombardment: Implications
for Early Life". AGU Fall Meeting Abstracts. Fall Meeting 2008:
American Geophysical Union. 1 (2008 Fall Meeting).
Bibcode:2008AGUFM.V11E..08A. Retrieved 24 May 2015.
Hopkins, Michelle; Harrison, T. Mark; Manning, Craig E. (2008), "Low
heat flow inferred from >4 Gyr zircons suggests
boundary interactions", Nature, 456 (7221): 493–496,
PMID 19037314 .
Valley, John W.; Peck, William H.; King, Elizabeth M. (1999), "Zircons
Are Forever", The Outcrop for 1999, University of Wisconsin-Madison,
retrieved January 10, 2006 – Evidence from detrital zircons
for the existence of continental crust and oceans on the
Earth 4.4 Gyr
Wilde, S. A.; Valley, J. W.; Peck, W. H. & Graham, C. M. (2001),
"Evidence from detrital zircons for the existence of continental crust
and oceans on the
Earth 4.4 Gyr ago", Nature, 409 (6817): 175–178,
doi:10.1038/35051550, PMID 11196637 .
Wyche, S.; Nelson, D. R. & Riganti, A. (2004), "4350–3130 Ma
detrital zircons in the Southern Cross Granite–Greenstone Terrane,
Western Australia: implications for the early evolution of the Yilgarn
Craton", Australian Journal of
Earth Sciences, 51 (1): 31–45,
Carley, Tamara L.; et al. (2014), "Iceland is not a magmatic analog
for the Hadean: Evidence from the zircon record",
Earth and Planetary
Science Letters, 405 (1): 85–97, Bibcode:2014E&PSL.405...85C,
Wikimedia Commons has media related to Hadean.
Peripatus.nz: Description of the
Astronoo.com: Hell of the Hadean
Hadean does not have any subdivisions recognized by the
International Commission on Stratigraphy. These subdivisions represent
one proposal that is loosely based on the lunar geologic time scale.
Geologic history of Earth
Quaternary (present–2.588 Mya)
Holocene (present–11.784 kya)
Pleistocene (11.784 kya–2.588 Mya)
Neogene (2.588–23.03 Mya)
Pliocene (2.588–5.333 Mya)
Miocene (5.333–23.03 Mya)
Paleogene (23.03–66.0 Mya)
Oligocene (23.03–33.9 Mya)
Eocene (33.9–56.0 Mya)
Paleocene (56.0–66.0 Mya)
Cretaceous (66.0–145.0 Mya)
Late (66.0–100.5 Mya)
Early (100.5–145.0 Mya)
Jurassic (145.0–201.3 Mya)
Late (145.0–163.5 Mya)
Middle (163.5–174.1 Mya)
Early (174.1–201.3 Mya)
Triassic (201.3–251.902 Mya)
Late (201.3–237 Mya)
Middle (237–247.2 Mya)
Early (247.2–251.902 Mya)
Permian (251.902–298.9 Mya)
Lopingian (251.902–259.8 Mya)
Guadalupian (259.8–272.3 Mya)
Cisuralian (272.3–298.9 Mya)
Carboniferous (298.9–358.9 Mya)
Pennsylvanian (298.9–323.2 Mya)
Mississippian (323.2–358.9 Mya)
Devonian (358.9–419.2 Mya)
Late (358.9–382.7 Mya)
Middle (382.7–393.3 Mya)
Early (393.3–419.2 Mya)
Silurian (419.2–443.8 Mya)
Pridoli (419.2–423.0 Mya)
Ludlow (423.0–427.4 Mya)
Wenlock (427.4–433.4 Mya)
Llandovery (433.4–443.8 Mya)
Ordovician (443.8–485.4 Mya)
Late (443.8–458.4 Mya)
Middle (458.4–470.0 Mya)
Early (470.0–485.4 Mya)
Cambrian (485.4–541.0 Mya)
Furongian (485.4–497 Mya)
Series 3 (497–509 Mya)
Series 2 (509–521 Mya)
Terreneuvian (521–541.0 Mya)
(541.0 Mya–2.5 Gya)
Neoproterozoic era (541.0 Mya–1 Gya)
Ediacaran (541.0-~635 Mya)
Cryogenian (~635-~720 Mya)
Tonian (~720 Mya-1 Gya)
Mesoproterozoic era (1–1.6 Gya)
Stenian (1-1.2 Gya)
Ectasian (1.2-1.4 Gya)
Calymmian (1.4-1.6 Gya)
Paleoproterozoic era (1.6–2.5 Gya)
Statherian (1.6-1.8 Gya)
Orosirian (1.8-2.05 Gya)
Rhyacian (2.05-2.3 Gya)
Siderian (2.3-2.5 Gya)
Archean eon² (2.5–4 Gya)
Neoarchean (2.5–2.8 Gya)
Mesoarchean (2.8–3.2 Gya)
Paleoarchean (3.2–3.6 Gya)
Eoarchean (3.6–4 Gya)
Hadean eon² (4–4.6 Gya)
kya = thousands years ago. Mya = millions years ago.
Gya = billions
years ago.¹ =
Phanerozoic eon. ² =
Source: (2017/02). International Commission on Stratigraphy. Retrieved
13 July 2015. Divisions of Geologic Time—Major Chronostratigraphic
and Geochronologic Units USGS Retrieved 10 March 2013.