Hadean

First eon of geological time, from about 4.6 billion years ago to 4 billion years ago

Hadean

~4540 – 4000 Ma

Pha.

Proterozoic

Archean

Had'n

File:Artist's concept of collision at HD 172555.jpg

Artist depiction of the hypothetical planet Thea colliding into early Earth

File:Earearth.png

Artist illustration of Earth and the Moon towards the middle/end of the Hadean eon

Chronology

−4500 --

−4000 --

−3500 --

−3000 --

−2500 --

−2000 --

−1500 --

−1000 --

−500 --

0 --

Hadean

Paleo

Meso

Neo

Paleo

Meso

Neo

Paleozoic

Mesozoic

Cenozoic

|

Scale: millions of years

Proposed subdivisions| See text

Etymology
Synonym(s)| Priscoan Period
Harland et al., 1989

Usage information
Celestial body| Earth
Regional usage| Global (ICS)
Definition
Chronological unit| Eon
Stratigraphic unit| Eonothem
First proposed by| Preston Cloud, 1972
Time span formality| Informal
Lower boundary definition| Formation of Earth
Lower boundary GSSP| N/A
GSSP ratified| N/A
Upper boundary definition| Defined Chronometrically
Upper boundary GSSP| N/A
GSSP ratified| N/A

The Hadean ( /heɪˈdiːən, ˈheɪdiən/ hay-DEE-ən, HAY-dee-ən) is a geologic eon of Earth history preceding the Archean. On Earth, the Hadean began with the planet's formation about 4.54 billion years ago[1][2] (although the start of the Hadean is defined as the age of the oldest solid material in the Solar System, found in some meteorites, about 4.567 billion years old).[3] The Hadean ended, as defined by the International Commission on Stratigraphy (ICS), 4 billion years ago.[4] As of 2016[update], the ICS describes its status as "informal".[5]

Hadean rocks are very rare, largely consisting of zircons from one locality in Western Australia.[6] Hadean geophysical models remain controversial among geologists: it appears that plate tectonics and the growth of continents may have started in the Hadean.[6] Earth in the early Hadean had a very thick carbon dioxide atmosphere, but eventually oceans of liquid water formed.

## Contents

* 1 Etymology
* 2 Subdivisions
* 3 Hadean rocks
* 4 Atmosphere and oceans
* 5 Geology
* 6 See also
* 7 References
* 8 Further reading
* 9 External links

## Etymology[edit | edit source]

"Hadean" (from Hades, the Greek god of the underworld, and the underworld itself) 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.

The term was coined by American geologist Preston Cloud, after the Greek mythical underworld Hades, originally to label the period before the earliest-known rocks on Earth.[7][8] W. Brian Harland later coined an almost synonymous term, the Priscoan Period, from priscus, the Latin word for 'ancient'.[9] Other, older texts refer to the eon as the Pre-Archean.[10][11]

## Subdivisions[edit | edit source]

See also: Proposed Precambrian timeline

Since few geological traces of this eon remain on Earth, there is no official subdivision. However, the 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 time intervals on Earth.

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 ago.
* 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 declining.

In 2010, an alternative scale was proposed that includes the addition of the Chaotian and Prenephelean eons preceding the Hadean and divides the Hadean into three eras with two periods each. The Paleohadean Era consists of the Hephaestean period (4.5–4.4 Ga) and the Jacobian period (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).[12] As of February 2022[update], this has not been adopted by the IUGS.[13]

## Hadean rocks[edit | edit source]

Further information: Oldest dated rocks

File:Jack Hills detrital zircons BSE micrographs.jpg

Backscatter electron micrograph of detrital zircons from the Hadean (4.404 ± 0.008 Ga) metasediments of the Jack Hills, Narryer Gneiss Terrane, Western Australia

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 Australia.[14][15]

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.[16] This zircon is a slight outlier, with the oldest consistently-dated zircon falling closer to 4.35 Ga[16]—around 200 million years after the hypothesized time of 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 4.22 Ga.[17]

## Atmosphere and oceans[edit | edit source]

A sizable quantity of water would have been in the material that formed Earth.[18] 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 the melting of one or two large regions of Earth. Earth's present composition suggests that there was not complete remelting as it is difficult to completely melt and mix huge rock masses.[19] However, a fair fraction of material should have been vaporized by this impact. The material would have condensed within 2000 years,[20] leaving behind hot volatiles which probably resulted in a heavy CO
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 the 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.[20] Studies of zircons have found that liquid water may have existed between 4.0 and 4.4 billion years ago, very soon after the formation of Earth.[21][22] For this time interval, meteorite impacts may be been less frequent than previously hypothesized, and Earth may have gone through long periods when liquid oceans and life were possible.[22]

Asteroid impacts during the Hadean and into the Archean would have periodically disrupted the ocean. The geological record from 3.2 Gya contains evidence of multiple impacts of objects up to 100 kilometres (62 mi) in diameter.[23] Each such impact would have boiled off up to 100 metres (330 ft) of a global ocean, and temporarily raised the atmospheric temperature to 500 °C (932 °F).[23]

## Geology[edit | edit source]

File:Hadean and Archean continents.gif

Evolution of continental crust and ocean depths, per Korenaga

A 2008 study of zircons found that Australian Hadean rock contains minerals pointing to the existence of plate tectonics as early as 4 billion years ago (approximately 600 million years after Earth's formation).[24] However, some geologists suggest that the zircons could have been formed by meteorite impacts.[25] The direct evidence of Hadean geology from zircons is limited, because the zircons are largely gathered in one locality in Australia.[6][26] Geophysical models are underconstrained, but can paint an general picture of the state of Earth in the Hadean.[6][27]

Mantle convection in the Hadean was likely vigorous, due to lower viscosity.[6] The lower viscosity was due to the high levels of radiogenic heat and the fact that water in the mantle had not yet fully outgassed.[28] Whether the vigorous convection led to plate tectonics in the Hadean or was confined under a rigid lid is still a matter of debate.[6][26][29][30] The presence of an ocean during the Hadean is generally accepted, due to zircon evidence.[26][31] The presence of oceans are thought to trigger plate tectonics.[32] The removal of the CO2-rich early atmosphere also indicates that plate tectonics were active in the Hadean.[33]

If plate tectonics occurred in the Hadean, it would have formed continental crust.[34] Different models predict different amounts of continental crust during the Hadean. The work of Dhiume et al. predicts that by the end of the Hadean, the continental crust had only 25% of today's area.[35] The models of Korenaga, et al. predict that the continental crust grew to present-day volume sometime between 4.0 and 4.2 Gya.[34][36]

The amount of exposed land in the Hadean is only loosely dependent on the amount of continental crust: it also depends on the ocean level.[6] In models where plate tectonics started in the Archean, Earth has a global ocean in the Hadean.[37][38] The high heat of the mantle may have made it difficult to support high elevations in the Hadean.[39][40] If continents did form in the Hadean, their growth competed with outgassing of water from the mantle.[6] Continents may have appeared in the mid-Hadean, and then disappeared under a thick ocean by the end of the Hadean.[41] The limited amount of land has implications for the origin of life.[6]

## See also[edit | edit source]

* Chaotian (geology) - Proposed era of the Hadean eon - Proposed era of the Hadean eon
* Faint young Sun paradox - Paradox concerning water on early Earth - Paradox concerning water on early Earth
* Formation and evolution of the Solar System
* Hadean zircon - Oldest-surviving crustal material from the Earth's earliest geological time period - Oldest-surviving crustal material from the Earth's earliest geological time period
* History of Earth - Development of planet Earth from its formation to the present day - Development of planet Earth from its formation to the present day – the first sections describe the formation of Earth
* Oldest dated rocks - Includes rocks over 4 billion years old from the Hadean Eon - Includes rocks over 4 billion years old from the Hadean Eon
* Precambrian - History of Earth 4600–539 million years ago - History of Earth 4600–539 million years ago
* Timeline of natural history

## References[edit | edit source]

1. ^ Dalrymple, G. Brent (2001). "The age of the Earth in the twentieth century: a problem (mostly) solved". Geological Society, London, Special Publications. 190 (1): 205–221. Bibcode:2001GSLSP.190..205D. doi:10.1144/gsl.sp.2001.190.01.14. S2CID 130092094. Retrieved 2022-10-02.
2. ^ "Age of the Earth". U.S. Geological Survey. 1997. Archived from the original on 23 December 2005. Retrieved 2022-10-03.
3. ^ Strachan, R.; Murphy, J.B.; Darling, J.; Storey, C.; Shields, G. (2020). "Precambrian (4.56–1 Ga)". In Gradstein, F.M.; Ogg, J.G.; Schmitz, M.D.; Ogg, G.M. (eds.). Geologic Time Scale 2020. Amsterdam: Elsevier. pp. 482–483. doi:10.1016/B978-0-12-824360-2.00016-4. ISBN 978-0-12-824360-2. S2CID 229513433.
4. ^ "International Chronostratigraphic Chart". International Commission on Stratigraphy. Retrieved 22 July 2020.
5. ^ Ogg, J. G.; Ogg, G.; Gradstein, F. M. (2016). A Concise Geologic Time Scale: 2016. Elsevier. p. 20\. ISBN 978-0-444-63771-0.
6. ^ a b c d e f g h i Korenaga, J (2021). "Was There Land on the Early Earth?". Life. 11 (11): 1142. doi:10.3390/life11111142. PMC 8623345. PMID 34833018.
7. ^ Cloud, Preston (1972). "A working model of the primitive Earth". American Journal of Science. 272 (6): 537–548. Bibcode:1972AmJS..272..537C. doi:10.2475/ajs.272.6.537.
8. ^ Bleeker, W. (2004). "10. Toward a "natural" Precambrian time scale". In Gradstein, Felix M.; Ogg, James G.; Smith, Alan G. (eds.). A Geologic Time Scale 2004. Cambridge, England, UK: Cambridge University Press. p. 145\. ISBN 9780521786737.
9. ^ Oxford Dictionary, "Priscoan"
10. ^ Shaw, D.M. (1975). Early History of the Earth. Proceedings of the NATO Advanced Study Institute. Leicester: John Wiley. pp. 33–53. ISBN 0-471-01488-5.
11. ^ Jarvis, Gary T.; Campbell, Ian H. (December 1983). "Archean komatiites and geotherms: Solution to an apparent contradiction". Geophysical Research Letters. 10 (12): 1133–1136. Bibcode:1983GeoRL..10.1133J. doi:10.1029/GL010i012p01133.
12. ^ "The eons of Chaos and Hades" (PDF). Solid Earth. 26 January 2010.
13. ^ "Chart". International Commission on Stratigraphy. February 2022. Retrieved 8 July 2022.
14. ^ 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.
15. ^ 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". Proc. Natl. Acad. Sci. U.S.A. Washington, D.C.: National Academy of Sciences. 112 (47): 14518–21. Bibcode:2015PNAS..11214518B. doi:10.1073/pnas.1517557112. ISSN 1091-6490. PMC 4664351. PMID 26483481.
16. ^ 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. Bibcode:2001Natur.409..175W. doi:10.1038/35051550. PMID 11196637. S2CID 4319774.
17. ^ 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 (4): 601–606. doi:10.5327/Z2317-48892013000400002.
18. ^ Drake, Michael J. (2005), "Origin of water in the terrestrial planets", Meteoritics & Planetary Science, 40 (4): 515–656, Bibcode:2005M&PS...40..515J, doi:10.1111/j.1945-5100.2005.tb00958.x.
19. ^ Taylor, G. Jeffrey. "Origin of the Earth and Moon". Solar System Exploration. NASA. Archived from the original on March 8, 2015.
20. ^ a b Sleep, NH; Zahnle, K; Neuhoff, PS (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..
21. ^ "Hell's milder side". Research School of Earth Sciences. Australian National University. Archived from the original on 2006-06-21.
"There was no such thing as hell on Earth". Media Release: Marketing & Communications. Australian National University. 18 November 2005. Archived from the original on 8 February 2006.
22. ^ a b Valley, John W.; Peck, William H.; King, Elizabeth M.; Wilde, Simon A. (April 2002). "A Cool Early Earth". Geology. 30 (4): 351–354. Bibcode:2002Geo....30..351V. doi:10.1130/0091-7613(2002)030<0351:ACEE>2.0.CO;2. PMID 16196254. Archived from the original on 2013-06-16. Retrieved 2006-08-22.
23. ^ a b Lowe, DR; Byerly, GR (2015). "Geologic record of partial ocean evaporation triggered by giant asteroid impacts, 3.29–3.23 billion years ago". Geology. 43 (6): 535–538. Bibcode:2015Geo....43..535L. doi:10.1130/G36665.1.
24. ^ Chang, Kenneth (December 2, 2008). "A New Picture of the Early Earth". The New York Times.
25. ^ Kenny, GG; Whitehouse, MJ; Kamber, BS; et al. (April 12, 2016). "Differentiated impact melt sheets may be a potential source of Hadean detrital zircon". Retrieved March 6, 2017.
26. ^ a b c Harrison, TM (2020). Hadean Earth. Cham, Switzerland: Springer.
27. ^ Korenaga, J; Planavsky, NJ; Evans, DAD (2017). "Global water cycle and the coevolution of Earth's interior and surface environment". Phil. Trans. R. Soc. A. 375 (2094): 20150393. Bibcode:2017RSPTA.37550393K. doi:10.1098/rsta.2015.0393. PMC 5394256. PMID 28416728. S2CID 2958757.
28. ^ Korenaga, J (2021). "Hadean geodynamics and the nature of early continental crust". Precambrian Res. 359: 106178. Bibcode:2021PreR..359j6178K. doi:10.1016/j.precamres.2021.106178. S2CID 233441822.
29. ^ Tang, M; Chen, K; Rudnick, RL (2016). "Archean upper crust transition from mafic to felsic marks the onset of plate tectonics". Science. 351 (6271): 372–375. Bibcode:2016Sci...351..372T. doi:10.1126/science.aad5513. PMID 26798012. S2CID 206643793.
30. ^ Windley, BF; Kusky, T; Polat, A (2021). "Onset of plate tectonics by the Eoarchean". Precambrian Res. 352: 105980. Bibcode:2021PreR..352j5980W. doi:10.1016/j.precamres.2020.105980. S2CID 228993361.
31. ^ Wilde, SA; Valley, JW; Peck, WH; Graham, CM (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. S2CID 4319774.
32. ^ Regenauer-Lieb, K; Yuen, DA; Branlund, J (2001). "The initiation of subduction: Criticality by addition of water?". Science. 294 (5542): 578–580. Bibcode:2001Sci...294..578R. doi:10.1126/science.1063891. PMID 11641494. S2CID 43547982.
33. ^ Sleep, NH; Zahnle, KJ; Lupu, RE (2014). "Terrestrial aftermath of the Moon-forming impact". Phil. Trans. R. Soc. A. 372 (2024): 20130172. Bibcode:2014RSPTA.37230172S. doi:10.1098/rsta.2013.0172. PMID 25114303. S2CID 6902632.
34. ^ a b Guo, M; Korenaga, J (2020). "Argon constraints on the early growth of felsic continental crust". Scientific Advances. 6 (21): eaaz6234. Bibcode:2020SciA....6.6234G. doi:10.1126/sciadv.aaz6234. PMC 7314546. PMID 32671213.
35. ^ Dhuime, B; Hawkesworth, CJ; Cawood, PA; Storey, CD (2012). "A change in the geodynamics of continental growth 3 billion years ago". Science. 335 (6074): 1334–1336. Bibcode:2012Sci...335.1334D. doi:10.1126/science.1216066. PMID 22422979. S2CID 206538532.
36. ^ Rosas, JC; Korenaga, J (2018). "Rapid crustal growth and efficient crustal recycling in the early Earth: Implications for Hadean andArchean geodynamics". Earth Planet. Sci. Lett. 494: 42–49. Bibcode:2018E&PSL.494...42R. doi:10.1016/j.epsl.2018.04.051. S2CID 13666395.
37. ^ Russell, MJ (2021). "The "Water Problem", the illusory pond and life's submarine emergence—A review". Life. 11 (5): 429. doi:10.3390/life11050429. PMC 8151828. PMID 34068713.
38. ^ Voosen, P (2021). "Ancient Earth was a water world". Science. 371 (6534): 1088–1089. Bibcode:2021Sci...371.1088V. doi:10.1126/science.371.6534.1088. PMID 33707245. S2CID 232206926.
39. ^ Monteux, J; Andrault, D; Guitreau, M; Samuel, H; Demouchy, S (2020). "A mushy Earth's mantle for more than 500 Myr after the magma ocean solidification". Geophys. J. Int. 221 (2): 1165–1181. doi:10.1093/gji/ggaa064.
40. ^ Rey, PF; Coltice, N (2008). "Neoarchean lithospheric strengthening and the coupling of Earth's geochemical reservoirs". Geology. 36 (8): 635–638. Bibcode:2008Geo....36..635R. doi:10.1130/G25031A.1;.`{{cite journal}}`: CS1 maint: ignored DOI errors (link)
41. ^ Bada, JL; Korenaga, J (2018). "Exposed areas above sea level on Earth >3.5 Gyr ago: Implications for prebiotic and primitive biotic chemistry". Life. 8 (4): 55. doi:10.3390/life8040055. PMC 6316429. PMID 30400350.

## Further reading[edit | edit source]

* Hopkins, Michelle; Harrison, T. Mark; Manning, Craig E. (2008), "Low heat flow inferred from >4 Gyr zircons suggests Hadean plate boundary interactions", Nature, 456 (7221): 493–496, Bibcode:2008Natur.456..493H, doi:10.1038/nature07465, PMID 19037314, S2CID 4417456.
* Valley, John W.; Peck, William H.; King, Elizabeth M. (1999), "Zircons Are Forever", The Outcrop for 1999, University of Wisconsin-Madison, archived from the original on March 16, 2012, retrieved January 10, 2006 – Evidence from detrital zircons for the existence of continental crust and oceans on the Earth 4.4 Gyr ago.
* 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, Bibcode:2001Natur.409..175W, doi:10.1038/35051550, PMID 11196637, S2CID 4319774.
* 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, Bibcode:2004AuJES..51...31W, doi:10.1046/j.1400-0952.2003.01042.x.
* 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, doi:10.1016/j.epsl.2014.08.015.
* Marchi, S.; et al. (2014), "Widespread mixing and burial of Earth's Hadean crust by asteroid impacts", Nature, 511: 578–582, doi:10.1038/nature13539

## External links[edit | edit source]

File:Commons-logo.svg

Wikimedia Commons has media related to Hadean.

* Peripatus.nz: Description of the Hadean Era
* Hadean (chronostratigraphy scale)

* v
* t
* e

Hadean Eon

* Cryptic
* Basin Groups
* Nectarian
* Lower Imbrian

The 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 timescale.

* v
* t
* e

Geological history of Earth

Cenozoic Era
(66.0 Ma–present)|

| Quaternary (2.58 Ma–present)|

* Pleistocene (2.58 Ma–11.8 ka)
* Holocene (11.8 ka–present)

|

Neogene (23.0–2.58 Ma)|

* Miocene (23.0–5.33 Ma)
* Pliocene (5.33–2.59 Ma)

Paleogene (66.0–23.0 Ma)|

* Paleocene (66.0–56.0 Ma)
* Eocene (56.0–33.9 Ma)
* Oligocene (33.9–23.0 Ma)

Mesozoic Era
(252–66.0 Ma)|

| Cretaceous (145–66.0 Ma)|

* Early (145–100 Ma)
* Late (100–66.0 Ma)

|

Jurassic (201–145 Ma)|

* Early (201–174 Ma)
* Middle (174–164 Ma)
* Late (164–145 Ma)

Triassic (252–201 Ma)|

* Early (252–247 Ma)
* Middle (247–237 Ma)
* Late (237–201 Ma)

Paleozoic Era
(539–252 Ma)|

| Permian (299–252 Ma)|

* Cisuralian (299–272 Ma)
* Guadalupian (272–260 Ma)
* Lopingian (260–252 Ma)

|

Carboniferous (359–299 Ma)|

* Mississippian (359–323 Ma)
* Pennsylvanian (323–299 Ma)

Devonian (419–359 Ma)|

Silurian (444–419 Ma)|

* Llandovery (444–433 Ma)
* Wenlock (433–427 Ma)
* Ludlow (427–423 Ma)
* Pridoli (423–419 Ma)

Ordovician (485–444 Ma)|

Cambrian (539–485 Ma)|

* Terreneuvian (539–521 Ma)
* Series 2 (521–509 Ma)
* Miaolingian (509–497 Ma)
* Furongian (497–485 Ma)

Proterozoic Eon
(2.5 Ga–539 Ma)|

| Neoproterozoic (1 Ga–539 Ma)|

* Tonian (1 Ga–720 Ma)
* Cryogenian (720–635 Ma)
* Ediacaran (635–539 Ma)

|

Mesoproterozoic (1.6–1 Ga)|

* Calymmian (1.6–1.4 Ga)
* Ectasian (1.4–1.2 Ga)
* Stenian (1.2–1 Ga)

Paleoproterozoic (2.5–1.6 Ga)|

* Siderian (2.5–2.3 Ga)
* Rhyacian (2.3–2.05 Ga)
* Orosirian (2.05–1.8 Ga)
* Statherian (1.8–1.6 Ga)

Archean Eon (4–2.5 Ga)|

* Eoarchean (4–3.6 Ga)
* Paleoarchean (3.6–3.2 Ga)
* Mesoarchean (3.2–2.8 Ga)
* Neoarchean (2.8–2.5 Ga)

Hadean Eon (4.6–4 Ga)|

ka = kiloannum (thousands years ago); Ma = megaannum (millions years ago); Ga = gigaannum (billions years ago).
See also: Geologic time scale • •
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