124 Sentences With "Hadean" | Random Sentence Generator

Hadean was founded by Rashid Mansoor (CEO) and Alec Mocatta (Chief Architect).

Back during the Hadean, asteroids regularly produced craters thousands of kilometers in diameter.

We call our planet's earliest era the Hadean because it was likely quite hellish.

The firm has also recently invested in blockchain startup Ledger and cloud OS startup Hadean.

Dr. Nutman believes life could have survived through the end of the Hadean and the bombardment.

It was a hellacious period on our planet often called the "Hadean," after the Greek god Hades.

As a result, they are the only rocks left over from the Hadean, making them invaluable time capsules.

Being forced to occupy an exterior I had no say in choosing can feel like a Hadean punishment.

"Given the predicted high flux of meteorites in the late Hadean," the hellish era just after the Earth formed, from 4.6 billion to 4.0 billion years ago, "impact melting may have been the predominant mechanism that generated Hadean felsic rocks," the authors write in the new paper published in Nature Geoscience.

For him and his colleagues, gazing into the Hadean labyrinths of a restless underwater volcano holds another, more visceral appeal.

Was the era as hellish as its name, "Hadean" implies, or was Earth always a water-rich orb with moving plates?

" The team's results are published in the journal Nature Geoscience, and is titled " Formation of Hadean granites by melting of igneous crust.

But some geologists now favor a milder version of the Hadean, with the rain of asteroids quickly tapering off after the moon was formed.

This may sound far-fetched, but it's clearly a claim that has convinced investors, since Hadean has now closed a seed round of $2.6m.

The discovery shows that life arose on Earth relatively early in its history, and that it was able to survive the harsh conditions of the Hadean epoch.

Based largely on Apollo samples toted home by moonwalking astronauts, scientists came to believe that in the Earth's Hadean age, there were at least two distinct epochs of solar system billiards.

Generally, folks think Hadean Earth might have been a hellish world that looked a lot like our rocky neighbor planets Mars or Venus, which have mafic crusts with no plate tectonics.

With Hadean, a single developer logs into the cloud-based platform and can instantly run complex algorithms on data at any scale without the need for any engineering resource or management.

But the Hadean was so called because of the hellish conditions thought to have prevailed, including cataclysmic meteorite impacts that boiled the oceans into steam and turned Earth's surface into molten lava.

But given that the Earth was subjected to impacts during the Hadean eon, when the planet was forming 4.6 billion years ago, bits of Earth on the moon don't seem surprising to Kring and his team.

The new evidence presented by Nutman and his colleagues strengthen the hypothesis that life emerged on Earth over 4 billion years ago during the Hadean epoch, a mere 540 million years after the formation of the planet.

The infant world would have been rent by volcanism and bombarded by other planetary crumbs, making for an environment so horrible, and so inhospitable to life, that the geologic era is named the Hadean, for the Greek underworld.

Taken together, the latest evidence from the ancient Earth and from the moon is painting a picture of a very different Hadean Earth: a stoutly solid, temperate, meteorite-clear and watery world, an Eden from the very beginning.

In the standard paradigm of the Hadean eon, these strikes culminated in an assault dubbed the Late Heavy Bombardment, also known as the lunar cataclysm, in which asteroids emigrated to the inner solar system and pounded the rocky planets.

Dr. Nutman argues that life must therefore have originated even earlier, probably in the late Hadean stage of Earth's history, which lasted from 4.65 billion years ago — when the planet formed from debris in orbit around the sun — to 4 billion years ago.

Still, even when the Hadean ended, a final rain of large asteroids descended on Earth at the beginning of the ensuing Archaean stage, possibly set loose when the giant planets Saturn, Uranus and Neptune drifted out into the Kuiper belt of asteroids.

The lead authors of the new study, Jeremy Bellucci from the Swedish Museum of Natural History and Alexander Nemchin from Curtin University in Australia, say this happened around 21970 billion years ago during the Hadean Eon—a time when the fledgling Earth was regularly struck by large objects.

However, some tiny parts of the crust have not been melted, as some rare Hadean zircon grains included in much younger host rock were discovered. The examination of Hadean detrital or inherited grains of zircon can give evidence of geophysical conditions of the early earth.

Basin Groups refers to 9 subdivisions of the lunar Pre-Nectarian geologic period. It is the second era of the Hadean.

Backscatter electron micrograph of detrital zircons from the Hadean (4.404 ± 0.008 Ga) metasediments of the Jack Hills, Narryer Gneiss Terrane, Western Australia Artist's impression of Earth and Moon towards the end of the Hadean, when the first water vapor clouds and oceans appeared on Earth "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.

Hadean zircon is the oldest-surviving crustal material from the Earth's earliest geological time period, the Hadean eon, about 4 billion years ago. Zircon is a mineral that is commonly used for radiometric dating because it is highly resistant to chemical changes and appears in the form of small crystals or grains in most igneous and metamorphic host rocks. Aerial photo of the Jack Hills, Australia Hadean zircon has very low abundance around the globe because of recycling of material by plate tectonics. When the rock at the surface is buried deep in the Earth it is heated and can recrystallise or melt.

He gets beaten by a ground Hadean and dies when Yuno reaches him. Yuno becomes upset and stabs Aiba with the Book of the Dead.

Geochimica Et Cosmochimica Acta, 98, 202. The Hadean zircon with original uranium concentrations greater than 600 ppm is challenged by the effect of post- crystallization alteration.

The Origin of water on Earth is unknown; oceans are thought to have formed in the Hadean eon and may have been the impetus for the emergence of life.

The Nuvvuagituq Belt is bounded by eoarchean tonalites, trondhjemites and granodiorite aged around 3660 Ma, and further surrounded by younger approximately 2750 Ma tonalities. Surrounding tonalites, trondhjemites and granodiorites (TTGs) are the product of partial melting of Hadean Mafic lithologies, which was similar to the Ujaraaluk unit. The remelt products of "Hadean Ujaraaluk" and the exposed, eoarhcean Ujarraluk unit share similar geochemical composition i.e. isotopic ratio between 142-Neodymiun to 144-Neodymium.

Satellite image Location of the Jack Hills in Australia The Jack Hills are a range of hills in Mid West Western Australia. They are best known as the source of the oldest material of terrestrial origin found to date: Hadean zircons that formed around 4.39 billion years ago. These zircons have enabled ground-breaking research into the conditions on earth in the Hadean eon. In 2015, "remains of biotic life" were found in 4.1 billion-year-old rocks there.

The characteristics of Hadean zircons show early Earth history and the mechanism of Earth's processes in the past. Based on the properties of these zircon crystals, many different geological models were proposed.

It seems to have been much more active during the Hadean period, resulting in gravitational sorting of heavier molten iron, nickel, and sulphides to the core and lighter silicate minerals to the mantle.

Artist's conception of a protoplanetary disc During Hadean time (4.6-4 Ga), the Solar System was forming, probably within a large cloud of gas and dust around the sun, called an accretion disc from which Earth formed . The Hadean Eon is not formally recognized, but it essentially marks the era before we have adequate record of significant solid rocks. The oldest dated zircons date from about . Earth was initially molten due to extreme volcanism and frequent collisions with other bodies.

During the Hadean the Late Heavy Bombardment occurred (approximately ) during which a large number of impact craters are believed to have formed on the Moon, and by inference on Earth, Mercury, Venus and Mars as well.

For Earth, where this stage coincides with the Hadean Eon, the total number of widely occurring minerals is estimated to be 420, with over 100 more that were rare. Mars probably reached this stage of mineral evolution.

In the Archean Eon Western Massachusetts and Vermont were the eastern edge of Laurentia (now the Canadian Shield). Laurentia is believed to have originated at the end of the Hadean, making it one of the oldest regions with continental crust, as evidenced by the discovery of Acasta Gneiss in Canada. At the end of the Hadean massive eruptions of felsic lava became cool enough to form permanent crust. The felsic nature of Laurentia allowed it to float over the denser ocean basins that surrounded it, so it was not submerged under the then- forming oceans.

Since little or no geological evidence on Earth exists from the time spanned by the Pre-Nectarian period of the Moon, the Pre- Nectarian has been used as a guide by at least one notable scientific work to subdivide the unofficial terrestrial Hadean eon. In particular, it is sometimes found that the Hadean eon is subdivided into the Cryptic era and Basin Groups 1-9 (which collectively make up the Pre-Nectarian), and the Nectarian and Lower Imbrian. The first lifeforms (self replicating RNA molecules, see RNA world hypothesis) may have evolved on earth around 4 bya during this era.

"Oldest rocks on Earth found". NBC News. Retrieved 2009-02-01.O'Neil, Jonathan; Carlson, Richard W.; Francis, Don; Stevenson, Ross K. (2008-09-26). "Neodymium-142 Evidence for Hadean Mafic Crust". Science 321 (5897): 1828-1831\. . though the dating methods are disputed.

Since little or no geological evidence on Earth exists from the time spanned by the Early Imbrian epoch of the Moon, the Early Imbrian has been used by at least one notable scientific work as an unofficial subdivision of the terrestrial Hadean eon.

The Acasta orthogneisses of the Slave Craton, Canada, are regarded to be the oldest rocks on Earth, dated to 4.06 Ga, include protoliths such as TTGs, amphibolite, gabbro, granite, and diorite. It is possible that such early Hadean TTGs were a source of phosphorus for the first oceans and therefore contributed nutrients to the first abiogenic steps of life on Earth. No Hadean-aged zircon grains have been identified in the Nuvvuagittuq Supracrustal Belt in northern Quebec, but amphibolites have been dated to 4.28 Ga while 3.75 Ga-old banded iron formations indicate the minimum age of the belt. The Napier Mountains in Antarctica are of similar age.

The earliest undisputed evidence of life on Earth dates at least from 3.5 billion years ago, during the Eoarchean Era after a geological crust started to solidify following the earlier molten Hadean Eon. There are microbial mat fossils found in 3.48 billion-year-old sandstone discovered in Western Australia.

Geochimica Et Cosmochimica Acta, 70(18), A250. A uranium to ytterbium concentration ratio versus yttrium concentration plot (U/Yb vs Y) shows different trace elements signatures of zircon sources. Stars are the data for Kimberlite zircon, triangles are Hadean Jack Hills zircon and circles are ocean crust zircon.

The Earth, formed 4.5 Gya, was at first inhospitable to any living organisms. Based on numerous observations and studies of the geological time- scale, the Hadean Earth is thought to have had a secondary atmosphere, formed through degassing of the rocks that accumulated from planetesimal impactors. At first, it was thought that the Earth's atmosphere consisted of hydrogen compounds—methane, ammonia and Water vapor—and that life began under such reducing conditions, which are conducive to the formation of organic molecules. According to later models, suggested by studying ancient minerals, the atmosphere in the late Hadean period consisted largely of water vapor, nitrogen and carbon dioxide, with smaller amounts of carbon monoxide, hydrogen, and sulfur compounds.

A reconstruction of the origin of continental crust, which formed the greenstone belt, using geochemical, lithological, and structural clues, is predicated upon two assumptions: first, new Hadean crust formed laterally by the expelling and lateral accretion of mafic to ultramafic lavas. Then stabilization occurred through the re-melting of the crust. The reworked crust can be attributed to the burial, most likely through subduction, of hydrated materials, such as basalt, that were formed in the Hadean. Additionally, the source for tested rock samples came from a mantle depleted in titanium and niobium and enriched in lead, strontium, barium, rubidium, and light rare- earth elements, which, taken together, are indicative of arc-related basalts.

Supracrustal rocks (supra (Latin for "above")) are rocks that were deposited on the existing basement rocks of the crust, hence the name. They may be further metamorphosed from both sedimentary and volcanic rocks. The oldest minerals on Earth are detrital zircon grains from the Yilgarn Craton in the Mesoarchaean (3.2–2.8 Ga) Jack Hills, Western Australia dated to up to 4.4 Ga, meaning that granitic continental crust and probably supracrustal rocks formed during the Hadean, within 200 million years of Earth accretion. Most Hadean rocks were probably recycled into the mantle before the end of the eon, however, and such pre-4.0 Ga mineral inclusions, the only traces from the earliest rock formation on Earth, are rare.

The geological history of the Hadean eon of early earth is poorly known due to the lack of rock record older than 4.02 Ga (giga-annum or billion years).Willbold, Mojzsis, Chen, & Elliott. (2015). Tungsten isotope composition of the Acasta Gneiss Complex. Earth and Planetary Science Letters, 419, 168-177.

The Precambrian includes approximately 90% of geologic time. It extends from 4.6 billion years ago to the beginning of the Cambrian Period (about 541 Ma). It includes three eons, the Hadean, Archean, and Proterozoic. Major volcanic events altering the Earth's environment and causing extinctions may have occurred 10 times in the past 3 billion years.

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. 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.

Information on the earliest formation of the Slave Craton may be found in the Acasta Gneiss Complex, but due to the complex history, poor preservation, and lack of exposure much is still unknown about crustal forming processes in the Hadean and early Archean. Xenocrysts found within 3.94 Ga tonalitic gneisses of the Acasta Gneiss Complex have U–Pb dates of 4.2 Ga. These zircon xenocrysts originally crystallized in a granitic magma of crustal origin. Further evidence suggests that the 3.94 Ga tonalitic gneisses are at least partly derived from this 4.2 Ga granite magma, which indicates that crustal reworking was an important process in the Eoarchean. Zircons from this granite protolith shows similarities to zircons from the Yilgarn Craton in Western Australia, and may be evidence for continental crust forming in the Hadean Eon.

In particular, it is sometimes found that the Hadean is subdivided into the Cryptic, Basin Groups 1-9, Nectarian, and Early Imbrian. This notation is not entirely consistent with the above lunar geologic time scale in that the Cryptic and Basin Groups 1-9 (both of which are only informal terms that are not used in geologic maps) comprise the Pre-Nectarian period.

Columnar basalt at Szent György Hill, Hungary Vesicular basalt at Sunset Crater, Arizona. US quarter for scale. In the Hadean, Archean, and early Proterozoic eons of Earth's history, the chemistry of erupted magmas was significantly different from today's, due to immature crustal and asthenosphere differentiation. These ultramafic volcanic rocks, with silica (SiO2) contents below 45% are usually classified as komatiites.

The word 'Archean' comes from the ancient Greek word ('), meaning 'beginning, origin.' It was first used in 1872, when it meant "of the earliest geological age." Before the Hadean Eon was recognized, the Archean spanned Earth's early history from its formation about 4,540 million years ago (Mya) until 2,500 Mya. Instead of being based on stratigraphy, the beginning and end of the Archean Eon are defined chronometrically.

The Hadean, Archean and Proterozoic eons were as a whole formerly called the Precambrian. This covered the four billion years of Earth history prior to the appearance of hard-shelled animals. More recently, however, the Archean and Proterozoic eons have been subdivided into eras of their own. Geologic eras are further subdivided into geologic periods, although the Archean eras have yet to be subdivided in this way.

The metamorphic rock exposed in the outcrop was previously a granitoid that formed 4.03 billion years ago, an age based on radiometric dating of zircon crystals at 4.031 Ga. The Acasta Gneiss is important in establishing the early history of the continental crust. Acasta Gneiss was formed in the Basin Groups unofficial period of the Hadean eon, which came before the Archean: see Timetable of the Precambrian.

Cape supergroup, C, immediately before it. The W indicates when the Witwatersrand supergroup was laid down, very much further in the past. The graph also indicates the period during which banded ironstone formations were formed on earth, indicative of an oxygen-free atmosphere. The earth's crust was wholly or partially molten during the Hadean Eon; the oldest rocks on earth are therefore less than 4000 million years old.

She defines books as "small gods". Papaveria donated all the proceeds from their sales to Doctors Without Borders in the wake of the 2011 Japan earthquake and tsunami. Between 2010 and 2011 it became an imprint of Circle Six alongside Hadean Press (also founded by Erzebet YellowBoy Carr alongside her husband Dis) and the newly founded Alchemy Press in order to make the handling of the financial side smoother.

The earth's condition during Archean to Proterozoic (including Eoarchean era) serves as a crucial linkage between Hadean magma ocean to present-day plate tectonics. Various interpretations have been suggested to explain the prevalent tectonic style corresponding to Eoarchean geology. However it can be, in general, classified into two tectonic models, which are vertical tectonics and plate tectonics. Explanation on the release of large amount of mantle heat is the prominent concern.

Precambrian stromatolites in the Siyeh Formation, Glacier National Park. A 2002 study suggested that these 3.5 Gyo (billion year old) formations contain fossilized cyanobacteria microbes. This suggests they are evidence of one of the earliest life forms on Earth. Stromatolites in Shark Bay The earliest life on Earth existed more than 3.5 Gya (billion years ago), during the Eoarchean Era when sufficient crust had solidified following the molten Hadean Eon.

The Hadean ( ) is a geologic eon of the Earth pre-dating the Archean. It began with the formation of the Earth about 4.6 billion years ago and ended, as defined by the International Commission on Stratigraphy (ICS), 4 billion years ago. , the ICS describes its status as "informal". Geologist Preston Cloud coined the term in 1972, originally to label the period before the earliest- known rocks on Earth.

However, it is suggested that these two cratons have never been directly connected, which may indicate that the early Hadean crust was primarily continental granite. Trace isotope analysis show that these early granite rocks originated from a highly depleted mantle and suggest that large scale differentiation occurred before ~4.0 Ga. These zircon crystals may be important in furthering the understanding of the earliest crustal formation processes, as little is yet known.

Histograms for concordant Jack Hills zircons. This is a histogram of rapid initial survey of individual 207Pb/206Pb ages undertaken to identify the >4.2Ga population. There are 3 dominant peaks and 2 minor peaks.Holden P, Lanc P, Ireland TR, Harrison TM, Foster JJ, Bruce ZP (2009) Mass-spectrometric mining of Hadean zircons by automated SHRIMP multi-collector and single- collector U/Pb zircon age dating: The first 100 000 grains.

Modern plate tectonic theory Plate tectonic theory is widely accepted for the generation of crust. However, it's still an unknown how the early Earth was formed. With the Hadean rock record, most of the scientists concluded that the belief of a hellish early Earth devoid of ocean is wrong. Scientists have constructed different models to explain the thermal history in early history including continental growth model,Sohma, T. (1999).

The Precambrian era dates from the beginning of Earth's formation (4.6 billion years ago) to the beginning of the Cambrian Period, 542 million years ago. The Precambrian consists of the Hadean, Archaean and Proterozoic eons. Specifically, this article examines the Ediacaran, when the first multicellular bodies are believed to have arisen, as well as what caused the rise of multicellularity. This time period arose after the Snowball Earth of the mid Neoproterozoic.

A protoplanet, Theia, then collides with it, forming the Moon. Earth is inherently in the Hadean and Archean Eon, in which it is covered in lava and ravaged by volcanos, however, microorganisms still managed to form below the ocean. Although still not known, latest theory suggests that chemicals from submarine volcanos made the right recipe to create life. 2490 million years ago, the oxygenation of the atmosphere began, allowing animals to arise.

In the Jack Hills, Australia, scientists obtained a relatively comprehensive record of Hadean zircon crystals in contrast to other locations. The Jack Hills rocks are from the Archean eon, about 3.6 billion years old. However, the zircon crystals there are older than the rocks that contain them. Many investigations have been carried out to find the absolute age and properties of zircon, for example the isotope ratios, mineral inclusions, and geochemistry of zircon.

Nuvvuagittuq Greenstone Belt (NGB) is located in the Northern Quebec, covering approximately 10 km2 of area in Hudson Bay. It resembles a north-closing synform that plunges towards the south direction. The true age of NGB is still controversial and between 4.4 Gyr year to 3.8 Gyr old. The 4.4-Gyr-old zircon in NGB does not, by its low isotopic ratio of 142-Neodymium to 144-Neodymium, represent that the mafic host rock is also of Hadean age.

Correlation between sunspots and climate and tenuous at best. Three to four billion years ago, the Sun emitted only 75% as much power as it does today. If the atmospheric composition had been the same as today, liquid water should not have existed on the Earth's surface. However, there is evidence for the presence of water on the early Earth, in the Hadean and Archean eons, leading to what is known as the faint young Sun paradox.

Traditionally it was thought that during the period between 4.28 and 3.8 Gya, changes in the orbits of the giant planets may have caused a heavy bombardment by asteroids and comets that pockmarked the Moon and the other inner planets (Mercury, Mars, and presumably Earth and Venus). This would likely have repeatedly sterilized the planet, had life appeared before that time. Geologically, the Hadean Earth would have been far more active than at any other time in its history.

A cognate Latin word aevum or aeuum (cf. ) for "age" is present in words such as longevity and mediaeval. Although the term aeon may be used in reference to a period of a billion years (especially in geology, cosmology and astronomy), its more common usage is for any long, indefinite period. Aeon can also refer to the four aeons on the geologic time scale that make up the Earth's history, the Hadean, Archean, Proterozoic, and the current aeon, Phanerozoic.

Other than the plutons, plentiful Eoarchean detrital zircons were reported from the metamorphosed sedimentary rocks in eastern Hebei and few in Anshan. Biotite schist, fuchsite quartzite and paragneiss recorded an isotopic age of 3.88–3.55 billion years. This further reinforces the existence of a Hadean- Eoarchean crust, which later became the sedimentary protolith of the metamorphosed sedimentary rocks. In Xinyang, at the southwestern edge of the Eastern Block, 3.6 billion-year-old zircons from felsic granulite xenoliths were found.

Since there is no strong evidence depicting the early Earth's true environment, many models are generated to explain early Earth history. The high value of Hadean heat production and impact flux proved that continental crust did not exist, which is very different from the modern process. In the absence of large amount of undistributed data and within the constraints of analytical methods, calculation on geophysics and planetary science has been rapidly developed to explore this new area of knowledge.

The geologic time scale encompasses the history of the Earth.International Commission on Stratigraphy . stratigraphy.org It is bracketed at the earliest by the dates of the first Solar System material at 4.567 Ga (or 4.567 billion years ago) and the formation of the Earth at 4.54 Ga (4.54 billion years), which is the beginning of the informally recognized Hadean eona division of geologic time. At the later end of the scale, it is marked by the present day (in the Holocene epoch).

The Swazian is a poorly defined geological stage in South Africa extending from about four to three billion years ago, encompassing some of the Hadean and much of the Archean on the Geologic time scale. Other scales assign the Swazian to parts of the Paleoarchean and Mesoarchean, 3.5 to 2.8 billion years ago. The Swazian is not recognized by the International Commission on Stratigraphy nor by the Geological Society of America, the two most widely accepted developers of international geologic time scales.

Other studies of zircons found in Australian Hadean rock point to the existence of plate tectonics as early as 4 billion years ago. If true, that implies that rather than a hot, molten surface and an atmosphere full of carbon dioxide, early Earth's surface was much as it is today. The action of plate tectonics traps vast amounts of CO2, thereby reducing greenhouse effects, and leading to a much cooler surface temperature, and the formation of solid rock and liquid water.

The age of the Earth is about 4.54 billion years. The earliest undisputed evidence of life on Earth dates at least from 3.5 billion years ago, during the Eoarchean Era after a geological crust started to solidify following the earlier molten Hadean Eon. There are microbial mat fossils found in 3.48 billion-year-old sandstone discovered in Western Australia. Other early physical evidence of a biogenic substance is graphite in 3.7 billion-year-old meta-sedimentary rocks discovered in Western Greenland.

A 2018 study from the University of Bristol, applying a molecular clock model, places the LUCA shortly after 4.5 billion years ago, within the Hadean. In March 2017, fossilized microorganisms (microfossils) were announced to have been discovered in hydrothermal vent precipitates from an ancient sea-bed in the Nuvvuagittuq Belt of Quebec, Canada. These may be as old as 4.28 billion years, the oldest evidence of life on Earth, suggesting "an almost instantaneous emergence of life" after ocean formation 4.41 billion years ago.

Three to four billion years ago the Sun emitted only 70% of its current power.The Sun's evolution Under the present atmospheric composition, this past solar luminosity would have been insufficient to prevent water from uniformly freezing. There is nonetheless evidence that liquid water was already present in the Hadean and Archean eons, leading to what is known as the faint young Sun paradox. Hypothesized solutions to this paradox include a vastly different atmosphere, with much higher concentrations of greenhouse gases than currently exist.

Evidence of life in the Late Hadean is more controversial. In 2015, biogenic carbon was detected in zircons dated to 4.1 billion years ago, but this evidence is preliminary and needs validation. Earth was very hostile to life before 4.2–4.3 Ga and the conclusion is that before the Archean Eon, life as we know it would have been challenged by these environmental conditions. While life could have arisen before the Archean, the conditions necessary to sustain life could not have occurred until the Archean Eon.

It serves as an ideal place to study how the crust was formed in the past and the related tectonic settings. Geologists are able to deduce the past environments and tectonic events by studying geological records like rocks and geological structures. The oldest components of the Eastern Block were first formed more than 4 billion years ago (the Hadean Eon). It later experienced numerous geological events between 3.8 and 1.85 billion years ago (the Eoarchean to Paleoproterozoic Era), including recurring volcanic eruptions and metamorphic events.

Hefner – The Evolutionary Epic – Zygon, vol.44 #1, March 2009, page 5,6 Biologist Ursula Goodenough also makes use of Hefner's weaving metaphor.Ursula Goodenough – The Sacred Depths of Nature, Oxford University Press US, 1998, page 272, Connie Barlow and Michael Dowd's Great Story divides the epic into 8 phases eons or eras: the Great Radiance, the Galactic, Hadean, Archean, Proterozoic, Paleozoic, Mesozoic, and Cenozoic. Great Story Timeline Dowd uses the term 'epic of evolution' to help construct his viewpoint of evolution theology (a form of theistic evolution).

Quartz-pebble metaconglomerate (Jack Hills Quartzite), the rock type that contains the Earth's oldest dated mineral grains (detrital zircon) Detrital zircons with ages greater than 4 billion years old have been found in these rocks, and a 4,404 +/-8 million year old zircon was found at Erawandoo Hill; this is the oldest dated material originating on Earth; the date is in the Cryptic era of the Hadean eon. They were found within a unit of the supracrustal sequence, a metamorphosed conglomerate considered to have an age ~3.0 Ga. Given the detrital nature of the rock unit, the zircons are sourced from pre-existing rocks which were then weathered and the resultant sediment deposited as sedimentary rock. The zircons and various aspects of their geochemistry provide evidence for the existence of continental-type crust on the surface of the earth during the Hadean eon, contrasting with earlier ideas on the earliest phase of Earth's history. Additionally, oxygen isotopic ratios in the zircons provide evidence for the presence of liquid water on the surface, if not a water ocean; also contrasting with earlier ideas on Earth's history.

The eonothem is not to be confused with the eon itself, which is a corresponding division of geologic time spanning a specific amount of (hundreds of millions of) years, during which rocks were formed that are classified within the eonothem. Eonothems have the same names as their corresponding eons, which means during the history of the Earth only four eonothems were formed. Oldest to newest these are the Hadean, Archean, Proterozoic, and Phanerozoic. A rock stratum, fossil or feature present in the "upper Phanerozoic" eonothem would therefore have originated within the "later Phanerozoic" eon.

The processes that gave rise to life on Earth are not completely understood, but there is substantial evidence that life came into existence either near the end of the Hadean Eon or early in the Archean Eon. The earliest evidence for life on Earth are graphite of biogenic origin found in 3.7 billion-year-old metasedimentary rocks discovered in Western Greenland. The earliest identifiable fossils consist of stromatolites, which are microbial mats formed in shallow water by cyanobacteria. The earliest stromatolites are found in 3.48 billion-year-old sandstone discovered in Western Australia.

This clock representation shows some of the major units of geological time and definitive events of Earth history. The Hadean eon represents the time before fossil record of life on Earth; its upper boundary is now regarded as 4.0 Ga (billion years ago). Other subdivisions reflect the evolution of life; the Archean and Proterozoic are both eons, the Palaeozoic, Mesozoic and Cenozoic are eras of the Phanerozoic eon. The three million year Quaternary period, the time of recognizable humans, is too small to be visible at this scale.

The Eoarchean was formerly officially unnamed and informally referred to as the first part of the Early Archean or Paleoarchean Era, both now obsolete names. The International Commission on Stratigraphy now officially recognizes the Eoarchean Era as the first part of the Archaean Eon, preceded by the Hadean Eon, during which the Earth is believed to have been essentially molten. The Eoarchaean's lower boundary or starting point of 4 Gya (4 billion years ago) is officially recognized by the International Commission on Stratigraphy. The name comes from two Greek words: eos (dawn) and archaios (ancient).

The Precambrian (or Pre-Cambrian, sometimes abbreviated pЄ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the Phanerozoic eon, which is named after Cambria, the Latinised name for Wales, where rocks from this age were first studied. The Precambrian accounts for 88% of the Earth's geologic time. The Precambrian (colored green in the timeline figure) is an informal unit of geologic time, subdivided into three eons (Hadean, Archean, Proterozoic) of the geologic time scale.

The Earth is about 4.54 billion years old. The earliest undisputed evidence of life on Earth dates from at least 3.5 billion years ago, during the Eoarchean Era after a geological crust started to solidify following the earlier molten Hadean Eon. Microbial mat fossils have been found in 3.48 billion-year-old sandstone in Western Australia. Other early physical evidence of a biogenic substance is graphite in 3.7 billion- year-old metasedimentary rocks discovered in Western Greenland as well as "remains of biotic life" found in 4.1 billion-year-old rocks in Western Australia.

By , Earth's magnetic field was established, which helped prevent the atmosphere from being stripped away by the solar wind. As the molten outer layer of Earth cooled it formed the first solid crust, which is thought to have been mafic in composition. The first continental crust, which was more felsic in composition, formed by the partial melting of this mafic crust. The presence of grains of the mineral zircon of Hadean age in Eoarchean sedimentary rocks suggest that at least some felsic crust existed as early as , only after Earth's formation.

Based on simulations, NASA space scientists John Chambers and Jack Lissauer have proposed the existence of a planet between Mars and the asteroid belt, going in a successively eccentric and unstable orbit, 4 billion years ago. They connect this planet, which they name Planet V, and its disappearance with the Late Heavy Bombardment episode of the Hadean era. Chambers and Lissauer also claim this Planet V most probably ended up crashing into the Sun. Unlike the disruption theory's fifth planet, "Planet V" is not credited with creating the asteroid belt.

The earth's crust was wholly or partially molten during the Hadean Eon; the oldest rocks on earth are therefore less than 4000 million years old. One of the first microcontinents to form was the Kaapvaal Craton, which forms the foundation of the north- eastern part of the country. The assembly and break-up of Gondwana are, in terms of the earth's and South Africa's geological history, relatively recent events. Klein Swartberg Range, seen from the Laingsburg area Folded rock formations of the Swartberg Southern Gondwana during the Cambrian-Ordovician Periods.

The Eoarchean (; also spelled Eoarchaean) is the first era of the Archean Eon of the geologic record for which the Earth has a solid crust. It spans 400 million years from the end of the Hadean Eon 4 billion years ago (4000 Mya) to the start of the Paleoarchean Era 3600 Mya. The beginnings of life on Earth have been dated to this era and evidence of cyanobacteria date to 3500 Mya, just outside this era. At that time, the atmosphere was without oxygen and the pressure values ranged from 10 to 100 bar (around 10 to 100 present-time atmospheres).

The Cryptic era is an informal term for the earliest geologic evolution of the Earth and Moon. It is the oldest (informal) era of the Hadean eon, and it is commonly accepted to have begun close to 4533 million (about 4.533 billion) years ago when the Earth and Moon formed. No samples exist to date the transition between the Cryptic era and the following Basin Groups era for the Moon (see also Pre-Nectarian), though sometimes it is stated that this era ended 4150 million years ago for one or both of these bodies.Harland, Walter Brian , et al.

This requires the presence of an atmosphere. The cool early Earth theory covers a range from about 4.4 to about 4.1 billion years. A September 2008 study of zircons found that Australian Hadean rock holds minerals pointing to the existence of plate tectonics as early as 4 billion years ago (approximately 600 million years after Earth's formation). 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.

Less than 1% of zircons detected around the world are over four billion years old. The probability of discovering at least a single over four billion-year-old zircon is very low. The abundance of over four billion-year-old zircon in the Jack Hills is anomalously high for most Archean quartzites and thus abundances probabilities of other spots are extremely low (between 0.2-0.02%).Harrison, T., Blichert- Toft, J., Mueller, W., Albarede, F., Holden, P., & Mojzsis, S. (2005). Heterogeneous Hadean hafnium; evidence of continental crust at 4.4 to 4.5 Ga. Science, 310(5756), 1947-1950.

The World Ocean is the habitat of 230,000 known species, but because much of it is unexplored, the number of species that exist in the ocean is much larger, possibly over two million. The origin of Earth's oceans is unknown; oceans are thought to have formed in the Hadean eon and may have been the cause for the emergence of life. Extraterrestrial oceans may be composed of water or other elements and compounds. The only confirmed large stable bodies of extraterrestrial surface liquids are the lakes of Titan, although there is evidence for the existence of oceans elsewhere in the Solar System.

The primary and largest catalogued divisions of time are periods called eons. The first eon was the Hadean, when the Earth and moon were predicted to be formed, lasting over 600 million years until the Archean, which is when the Earth had cooled enough for continents and the earliest known life to emerge. After about 2.5 billion years, oxygen generated by photosynthesizing single-celled organisms began to appear in the atmosphere marking the beginning of the Proterozoic. Finally, the Phanerozoic eon encompasses 541 million years of diverse abundance of multicellular life starting with the appearance of hard animal shells in the fossil record and continuing to the present.

The Noachian is a geologic system and early time period on the planet Mars characterized by high rates of meteorite and asteroid impacts and the possible presence of abundant surface water. The absolute age of the Noachian period is uncertain but probably corresponds to the lunar Pre-Nectarian to Early Imbrian periods of 4100 to 3700 million years ago, during the interval known as the Late Heavy Bombardment. Many of the large impact basins on the Moon and Mars formed at this time. The Noachian Period is roughly equivalent to the Earth's Hadean and early Archean eons when the first life forms likely arose.

TTG is a prevalent rock type in archean formations. All 3 regions contain an abundance of Archean felsic volcanic rocks, including tonalite, trondhjemite and granodiorite (TTG) series rocks, with minor granulite to amphibolite facies gneiss complexes, which means that the original characters of the rocks has been disturbed by at least one ductile deformation at deep crustal conditions. Eoarchean geology is important in investigating earth's tectonic history. It is because the earth had just undergone an transformation to the present-day-similar convective mode and lithosphere from a magma ocean in Hadean Eon, to either a protoplate tectonics or an unstable stagnant lithosphere lid at its infant stages.

This was accomplished by dating intruding gabbros and measuring neodymium isotope fractionation in less- deformed members of the Ujaraaluk unit. The age of 4321 Ma would make the Nuvvuagittuq Greenstone Belt the oldest known rocks on Earth. In 2012, further studies of detrital zircons taken from quartz–biotite schists in the NGB reported a maximum age of 3780 Ma. The latter study states that the 4321 Ma age is not reflective of the NGB, but rather, reflects isotope ratios inherited from Hadean crust that was melted to form the parent rocks of the NGB. As of March 2017, this disagreement in dating remained unresolved.

Though most scientists conceive of the early atmosphere as reducing, a 2011 article in Nature found that cerium oxidation in zircon—which comprises the oldest rocks on Earth at roughly 4.4 billion years of age—was comparable to that of present-day lava. This observation implies that Hadean atmospheric oxygen levels were similar to those of today. The research raises questions about how the jump from inorganic compounds to life-supporting amino acids and DNA occurred on earth and suggests those building blocks were delivered from elsewhere in the galaxy. The results however do not run contrary to existing theories on life's journey from anaerobic to aerobic organisms.

The main concept of the album is based around the Precambrian, an early period in the formation of Earth. Hadean/Archaean (disc one) is heavy and raw just like their previous album Aeolian while Proterozoic (disc two) is more post-metal-influenced with the inclusion of symphonic and electronic elements like their first album Fluxion. The production of the album lasted more than six months after their tour in Europe in late 2006. All the drum tracks done by Torge Liessmann and most of the guitar tracks were recorded at Studio57, near Kokkola, Finland, where producer Jonas Olsson had also recorded and produced Callisto´s album Noir.

The Phanerozoic Eon is the current geologic eon in the geologic time scale, and the one during which abundant animal and plant life has existed. It covers million years to the present, and it began with the Cambrian Period when animals first developed hard shells preserved in the fossil record. The time before the Phanerozoic, called the Precambrian, is now divided into the Hadean, Archaean and Proterozoic eons. The time span of the Phanerozoic starts with the sudden appearance of fossilized evidence of a number of animal phyla; the evolution of those phyla into diverse forms; the emergence and development of complex plants; the evolution of fish; the emergence of insects and tetrapods; and the development of modern fauna.

A stable crust was apparently in place by 4,433 Ma, since zircon crystals from Western Australia have been dated at 4,404 ± 8 Ma. The term "Precambrian" is recognized by the International Commission on Stratigraphy as the only "" in geologic time; it is so-called because it includes the Hadean (~4.6–4 billion), Archean (4–2.5 billion), and Proterozoic (2.5 billion—541 million) eons. (There is only one other eon: the Phanerozoic, 541 million-present.) "Precambrian" is still used by geologists and paleontologists for general discussions not requiring the more specific eon names. , the United States Geological Survey considers the term informal, lacking a stratigraphic rank. ''''' (from “earliest”) was a synonym for pre- Cambrian, or more specifically Archean.

Cloud was a member of the National Academy of Sciences for thirty years, he was chairman of the Geology Section and occupied positions in its Council and Executive Committee. In 1967-69 he headed the Academy's "Committee on Resources and Man," whose alarming report "Resources and Man" introduced to a wider public, among other things, the work on energy-resources of his friend M. King Hubbert, and the Hubbert peak theory of Peak oil production. He also gave the Hadean geologic eon, Earth's earliest, its name, using the Greek word for the Underworld to refer to a molten state of constant heat. Cloud was the author of over 200 scientific and lay publications.

The divisions of the lunar geologic time scale are based on the recognition of a few convenient geomorphological markers. While these divisions are extremely useful for ordering geological events in a relative manner, it is important to realize that the boundaries do not imply any fundamental change of geological processes. Furthermore, as the oldest geological periods of the Moon are based exclusively on the times of individual impact events (in particular, Nectaris, Imbrium, and Orientale), these punctual events will most likely not correspond to any specific geological event on the other terrestrial planets, such as Mercury, Venus, Earth, or Mars. Nevertheless, at least one notable scientific work has advocated using the lunar geological time scale to subdivide the Hadean eon of Earth's geologic time scale.

When the Archean began, the Earth's heat flow was nearly three times as high as it is today, and it was still twice the current level at the transition from the Archean to the Proterozoic (2,500 Ma). The extra heat was the result of a mix of remnant heat from planetary accretion, from the formation of the metallic core, and from the decay of radioactive elements. Although a few mineral grains are known to be Hadean, the oldest rock formations exposed on the surface of the Earth are Archean. Archean rocks are found in Greenland, Siberia, the Canadian Shield, Montana and Wyoming (exposed parts of the Wyoming Craton), the Baltic Shield, the Rhodope Massif, Scotland, India, Brazil, western Australia, and southern Africa.

43, Issue 16, pp. 8376-8383. The early Earth during the Hadean eon is believed by most scientists to have had a Venus-like atmosphere, with roughly 100 bar of CO2 and a surface temperature of 230 °C, and possibly even sulfuric acid clouds, until about 4.0 billion years ago, by which time plate tectonics were in full force and together with the early water oceans, removed the CO2 and sulfur from the atmosphere. Early Venus would thus most likely have had water oceans like the Earth, but any plate tectonics would have ended when Venus lost its oceans. Its surface is estimated to be about 500 million years old, so it would not be expected to show evidence of plate tectonics.

The Hadean environment would have been highly hazardous to modern life. Frequent collisions with large objects, up to 500 km in diameter, would have been sufficient to sterilize the planet and vaporize the oceans within a few months of impact, with hot steam mixed with rock vapor becoming high altitude clouds that would completely cover the planet. After a few months, the height of these clouds would have begun to decrease but the cloud base would still have been elevated for about the next thousand years. After that, it would have begun to rain at low altitude. For another two thousand years, rains would slowly have drawn down the height of the clouds, returning the oceans to their original depth only 3,000 y after the impact event.

The cool early Earth (CEE) theory posits that for part of the Hadean geological eon, at the beginning of Earth's history, it had a modest influx of bolides and a cool climate, allowing the presence of liquid water. This would have been after the extreme conditions of Earth's earliest history between 4.6 and 4.4 billion years (Ga) ago, but before the Late Heavy Bombardment of 4.1 to 3.8 Ga ago. In 2002 John Valley et al. argued that detrital zircons found in Western Australia, dating to 4.0–4.4 Ga ago, were formed at relatively low temperatures, that meteorite impacts may have been less frequent than previously thought, and that Earth may have gone through long periods when liquid oceans and life were possible.

In 2000, estimations suggested LUCA existed 3.5 to 3.8 billion years ago in the Paleoarchean era, a few hundred million years before the earliest fossil evidence of life, for which there are several candidates ranging in age from 3.48 to 4.28 billion years ago. A 2018 study from the University of Bristol, applying a molecular clock model, places the LUCA shortly after 4.5 billion years ago, within the Hadean. Charles Darwin first proposed the theory of universal common descent through an evolutionary process in his book On the Origin of Species in 1859: "Therefore I should infer from analogy that probably all the organic beings which have ever lived on this earth have descended from some one primordial form, into which life was first breathed." Later biologists have separated the problem of the origin of life from that of the LUCA.

As additional clues of the resulting megatsunami found in a New Jersey, US quarry, a dense marine bone bed was found on the Cretaceous–Paleogene boundary containing a mixture of dead sea animals with little or no damage from scavengers or predators. Also related to this tsunami was a dense dinosaur bone bed on the Cretaceous–Paleogene boundary found in Patagonia. A 2020 study mentioned that Expedition 364 drilled to a depth of below the sea floor to reach the peak ring, and discovered a massive hydrothermal system filled with magma, which modified ~1.4 × 105 km3 of Earth’s crust and lasted for hundreds of thousands of years; in addition, those hydrothermal system might support the impact origin of life hypothesis for the Hadean, when the entire surface of Earth was affected by impactors enormously larger than the Chicxulub impactor.

Oceans may have appeared first in the Hadean Eon, as soon as 200 My after the Earth formed, in a hot, 100 C, reducing environment, and the pH of about 5.8 rose rapidly towards neutral. This scenario has found support from the dating of 4.404 Gyo zircon crystals from metamorphosed quartzite of Mount Narryer in the Western Australia Jack Hills of the Pilbara, which provide evidence that oceans and continental crust existed within 150 Ma of Earth's formation. Despite the likely increased volcanism and existence of many smaller tectonic "platelets," it has been suggested that between 4.4-4.3 Gyo, the Earth was a water world, with little if any continental crust, an extremely turbulent atmosphere and a hydrosphere subject to intense ultraviolet (UV) light, from a T Tauri stage Sun, cosmic radiation and continued bolide impacts.

In particular, xenon is useful for calculations of water loss over time. Not only is it a noble gas (and therefore is not removed from the atmosphere through chemical reactions with other elements), but comparisons between abundances of its nine stable isotopes in the modern atmosphere reveal that the Earth lost at least one ocean of water early in its history, between the Hadean and Archean eras. Any water on Earth during the later part of its accretion would have been disrupted by the Moon-forming impact (~4.5 billion years ago), which likely vaporized much of Earth's crust and upper mantle and created 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 majority carbon dioxide atmosphere with hydrogen and water vapor.

In 2008 an age of 4.28 billion years was reported for an outcrop in the Nuvvuagittuq Greenstone Belt on the eastern shores of Hudson Bay, 40 kilometres south of Inukjuak, Quebec, Canada. However, the dating method used did not involve similar radiometric dating of zircon crystals and it remains somewhat contentious whether the reported date represents the age that the rock itself formed or a residual isotopic signature of older material that melted to form the rock.Discovery of world’s oldest rocks challenged, New Scientist, 26 September 2008 Mafic rocks from the Nuvvuagittuq Greenstone Belt have recorded isotopic compositions that can be produced only in the Hadean eon (i.e. older than 4 billion years ago) and the complete isotopic study of all the lithologies included in the Nuvvuagittuq Greenstone Belt suggests that it was formed nearly 4.4 billion years ago.

The rocks in question are part of a metamorphosed supracrustal sequence located at the south-western tip of the island. The sequence has been dated as no younger than 3.85 billion years old - that is, in the Hadean eon - based on the age of an igneous band that cuts the rock.Manning, CE, Mojzsis, SJ, Harrison, TM (2006) Geology, age and origin of supracrustal rocks at Akilia, West Greenland. American Journal of Science, v. 206, p. 303-366 The supracrustal sequence contains layers rich in iron and silica, which are variously interpreted as banded iron formation, chemical sediments from submarine hot springs, or hydrothermal vein deposits. Carbon in the rock, present as graphite, shows low levels of carbon-13, which may suggest an origin as isotopically light organic matter derived from living organisms.Schidlowski, M (1988) A 3,850-Million-Year Isotopic Record of Life From Carbon in Sedimentary-Rocks.

The oldest rock formation is, depending on the latest research, either part of the Isua Greenstone Belt, Narryer Gneiss Terrane, Nuvvuagittuq greenstone belt, Napier Complex, or the Acasta Gneiss (on the Slave Craton). The difficulty in assigning the title to one particular block of gneiss is that the gneisses are all extremely deformed, and the oldest rock may be represented by only one streak of minerals in a mylonite, representing a layer of sediment or an old dike. This may be difficult to find or map; hence, the oldest dates yet resolved are as much generated by luck in sampling as by understanding the rocks themselves. It is thus premature to claim that any of these rocks, or indeed that of other formations of Hadean gneisses, is the oldest formations or rocks on Earth; doubtless, new analyses will continue to change our conceptions of the structure and nature of these ancient continental fragments.

Paleomagnetic studies show Kenorland was in generally low latitudes until tectonic magma-plume rifting began to occur between 2.48 Ga and 2.45 Ga. At 2.45 Ga the Baltic Shield was over the equator and was joined to Laurentia (the Canadian Shield) and both the Kola and Karelia cratons. The protracted breakup of Kenorland during the Late Neoarchaean and early Paleoproterozoic Era 2.48 to 2.10 Gya, during the Siderian and Rhyacian periods, is manifested by mafic dikes and sedimentary rift-basins and rift-margins on many continents. On early Earth, this type of bimodal deep mantle plume rifting was common in Archaean and Neoarchaean crust and continent formation. Map of Kenorland breaking up 2.3 billion years ago The geological time period surrounding the breakup of Kenorland is thought by many geologists to be the beginning of the transition point from the deep- mantle-plume method of continent formation in the Hadean to Early Archean (before the final formation of the Earth's inner core) to the subsequent two- layer core-mantle plate tectonics convection theory.

Deep-sea hydrothermal vent or black smoker The deep sea vent, or alkaline hydrothermal vent, theory posits that life may have begun at submarine hydrothermal vents, Martin and Russell have suggested > that life evolved in structured iron monosulphide precipitates in a seepage > site hydrothermal mound at a redox, pH, and temperature gradient between > sulphide-rich hydrothermal fluid and iron(II)-containing waters of the > Hadean ocean floor. The naturally arising, three-dimensional > compartmentation observed within fossilized seepage-site metal sulphide > precipitates indicates that these inorganic compartments were the precursors > of cell walls and membranes found in free-living prokaryotes. The known > capability of FeS and NiS to catalyze the synthesis of the acetyl- > methylsulphide from carbon monoxide and methylsulphide, constituents of > hydrothermal fluid, indicates that pre-biotic syntheses occurred at the > inner surfaces of these metal-sulphide-walled compartments,... These form where hydrogen-rich fluids emerge from below the sea floor, as a result of serpentinization of ultra-mafic olivine with seawater and a pH interface with carbon dioxide-rich ocean water. The vents form a sustained chemical energy source derived from redox reactions, in which electron donors (molecular hydrogen) react with electron acceptors (carbon dioxide); see Iron–sulfur world theory.